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Watson SJ, Arisdakessian C, Petelo M, Keliipuleole K, Tachera DK, Okuhata BK, Frank KL. Groundwater microbial communities reflect geothermal activity on volcanic island. GEOBIOLOGY 2024; 22:e12591. [PMID: 38458993 PMCID: PMC11027952 DOI: 10.1111/gbi.12591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 01/23/2024] [Accepted: 02/19/2024] [Indexed: 03/10/2024]
Abstract
Studies of the effects of volcanic activity on the Hawaiian Islands are extremely relevant due to the past and current co-eruptions at both Mauna Loa and Kīlauea. The Big Island of Hawai'i is one of the most seismically monitored volcanic systems in the world, and recent investigations of the Big Island suggest a widespread subsurface connectivity between volcanoes. Volcanic activity has the potential to add mineral contaminants into groundwater ecosystems, thus affecting water quality, and making inhabitants of volcanic islands particularly vulnerable due to dependence on groundwater aquifers. As part of an interdisciplinary study on groundwater aquifers in Kona, Hawai'i, over 40 groundwater wells were sampled quarterly from August 2017 through March 2019, before and after the destructive eruption of the Kīlauea East Rift Zone in May 2018. Sample sites occurred at great distance (~80 km) from Kīlauea, allowing us to pose questions of how volcanic groundwater aquifers might be influenced by volcanic subsurface activity. Approximately 400 water samples were analyzed and temporally split by pre-eruption and post-eruption for biogeochemical analysis. While most geochemical constituents did not differ across quarterly sampling, microbial communities varied temporally (pre- and post-eruption). When a salinity threshold amongst samples was set, the greatest microbial community differences were observed in the freshest groundwater samples. Differential analysis indicated bacterial families with sulfur (S) metabolisms (sulfate reducers, sulfide oxidation, and disproportionation of S-intermediates) were enriched post-eruption. The diversity in S-cyclers without a corresponding change in sulfate geochemistry suggests cryptic cycling may occur in groundwater aquifers as a result of distant volcanic subsurface activity. Microbial communities, including taxa that cycle S, may be superior tracers to changes in groundwater quality, especially from direct inputs of subsurface volcanic activity.
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Affiliation(s)
- Sheree J Watson
- Pacific Biosciences Research Center, University of Hawai'i at Mānoa, Honolulu, Hawaii, USA
| | - Cédric Arisdakessian
- Department of Information and Computer Sciences, University of Hawai'i at Mānoa, Honolulu, Hawaii, USA
| | - Maria Petelo
- Pacific Biosciences Research Center, University of Hawai'i at Mānoa, Honolulu, Hawaii, USA
| | - Kekuʻiapōiula Keliipuleole
- Pacific Biosciences Research Center, University of Hawai'i at Mānoa, Honolulu, Hawaii, USA
- Department of Biology, University of Hawai'i at Mānoa, Honolulu, Hawaii, USA
| | - Diamond K Tachera
- Department of Earth Sciences, University of Hawai'i at Mānoa, Honolulu, Hawaii, USA
| | - Brytne K Okuhata
- Department of Earth Sciences, University of Hawai'i at Mānoa, Honolulu, Hawaii, USA
| | - Kiana L Frank
- Pacific Biosciences Research Center, University of Hawai'i at Mānoa, Honolulu, Hawaii, USA
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Beaver RC, Neufeld JD. Microbial ecology of the deep terrestrial subsurface. THE ISME JOURNAL 2024; 18:wrae091. [PMID: 38780093 PMCID: PMC11170664 DOI: 10.1093/ismejo/wrae091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 03/04/2024] [Accepted: 05/22/2024] [Indexed: 05/25/2024]
Abstract
The terrestrial subsurface hosts microbial communities that, collectively, are predicted to comprise as many microbial cells as global surface soils. Although initially thought to be associated with deposited organic matter, deep subsurface microbial communities are supported by chemolithoautotrophic primary production, with hydrogen serving as an important source of electrons. Despite recent progress, relatively little is known about the deep terrestrial subsurface compared to more commonly studied environments. Understanding the composition of deep terrestrial subsurface microbial communities and the factors that influence them is of importance because of human-associated activities including long-term storage of used nuclear fuel, carbon capture, and storage of hydrogen for use as an energy vector. In addition to identifying deep subsurface microorganisms, recent research focuses on identifying the roles of microorganisms in subsurface communities, as well as elucidating myriad interactions-syntrophic, episymbiotic, and viral-that occur among community members. In recent years, entirely new groups of microorganisms (i.e. candidate phyla radiation bacteria and Diapherotrites, Parvarchaeota, Aenigmarchaeota, Nanoloarchaeota, Nanoarchaeota archaea) have been discovered in deep terrestrial subsurface environments, suggesting that much remains unknown about this biosphere. This review explores the historical context for deep terrestrial subsurface microbial ecology and highlights recent discoveries that shape current ecological understanding of this poorly explored microbial habitat. Additionally, we highlight the need for multifaceted experimental approaches to observe phenomena such as cryptic cycles, complex interactions, and episymbiosis, which may not be apparent when using single approaches in isolation, but are nonetheless critical to advancing our understanding of this deep biosphere.
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Affiliation(s)
- Rachel C Beaver
- Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
| | - Josh D Neufeld
- Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
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3
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Newman-Portela AM, Krawczyk-Bärsch E, Lopez-Fernandez M, Bok F, Kassahun A, Drobot B, Steudtner R, Stumpf T, Raff J, Merroun ML. Biostimulation of indigenous microbes for uranium bioremediation in former U mine water: multidisciplinary approach assessment. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2024; 31:7227-7245. [PMID: 38157180 PMCID: PMC10821841 DOI: 10.1007/s11356-023-31530-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 12/09/2023] [Indexed: 01/03/2024]
Abstract
Characterizing uranium (U) mine water is necessary to understand and design an effective bioremediation strategy. In this study, water samples from two former U-mines in East Germany were analysed. The U and sulphate (SO42-) concentrations of Schlema-Alberoda mine water (U: 1 mg/L; SO42-: 335 mg/L) were 2 and 3 order of magnitude higher than those of the Pöhla sample (U: 0.01 mg/L; SO42-: 0.5 mg/L). U and SO42- seemed to influence the microbial diversity of the two water samples. Microbial diversity analysis identified U(VI)-reducing bacteria (e.g. Desulfurivibrio) and wood-degrading fungi (e.g. Cadophora) providing as electron donors for the growth of U-reducers. U-bioreduction experiments were performed to screen electron donors (glycerol, vanillic acid, and gluconic acid) for Schlema-Alberoda U-mine water bioremediation purpose. Thermodynamic speciation calculations show that under experimental conditions, U(VI) is not coordinated to the amended electron donors. Glycerol was the best-studied electron donor as it effectively removed 99% of soluble U, 95% of Fe, and 58% of SO42- from the mine water, probably by biostimulation of indigenous microbes. Vanillic acid removed 90% of U, and no U removal occurred using gluconic acid.
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Affiliation(s)
- Antonio M Newman-Portela
- Department of Microbiology, Faculty of Science, University of Granada, Avda. Fuentenueva S/N, 18071, Granada, Spain.
- Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328, Dresden, Germany.
| | - Evelyn Krawczyk-Bärsch
- Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328, Dresden, Germany
| | - Margarita Lopez-Fernandez
- Department of Microbiology, Faculty of Science, University of Granada, Avda. Fuentenueva S/N, 18071, Granada, Spain
| | - Frank Bok
- Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328, Dresden, Germany
| | - Andrea Kassahun
- WISMUT GmbH, Jagdschänkenstraße 29, 09117, Chemnitz, Germany
| | - Björn Drobot
- Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328, Dresden, Germany
| | - Robin Steudtner
- Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328, Dresden, Germany
| | - Thorsten Stumpf
- Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328, Dresden, Germany
| | - Johannes Raff
- Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328, Dresden, Germany
| | - Mohamed L Merroun
- Department of Microbiology, Faculty of Science, University of Granada, Avda. Fuentenueva S/N, 18071, Granada, Spain
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Hart R, Cardace D. Mineral Indicators of Geologically Recent Past Habitability on Mars. Life (Basel) 2023; 13:2349. [PMID: 38137950 PMCID: PMC10744562 DOI: 10.3390/life13122349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 11/25/2023] [Accepted: 12/05/2023] [Indexed: 12/24/2023] Open
Abstract
We provide new support for habitable microenvironments in the near-subsurface of Mars, hosted in Fe- and Mg-rich rock units, and present a list of minerals that can serve as indicators of specific water-rock reactions in recent geologic paleohabitats for follow-on study. We modeled, using a thermodynamic basis without selective phase suppression, the reactions of published Martian meteorites and Jezero Crater igneous rock compositions and reasonable planetary waters (saline, alkaline waters) using Geochemist's Workbench Ver. 12.0. Solid-phase inputs were meteorite compositions for ALH 77005, Nakhla, and Chassigny, and two rock units from the Mars 2020 Perseverance rover sites, Máaz and Séítah. Six plausible Martian groundwater types [NaClO4, Mg(ClO4)2, Ca(ClO4)2, Mg-Na2(ClO4)2, Ca-Na2(ClO4)2, Mg-Ca(ClO4)2] and a unique Mars soil-water analog solution (dilute saline solution) named "Rosy Red", related to the Phoenix Lander mission, were the aqueous-phase inputs. Geophysical conditions were tuned to near-subsurface Mars (100 °C or 373.15 K, associated with residual heat from a magmatic system, impact event, or a concentration of radionuclides, and 101.3 kPa, similar to <10 m depth). Mineral products were dominated by phyllosilicates such as serpentine-group minerals in most reaction paths, but differed in some important indicator minerals. Modeled products varied in physicochemical properties (pH, Eh, conductivity), major ion activities, and related gas fugacities, with different ecological implications. The microbial habitability of pore spaces in subsurface groundwater percolation systems was interrogated at equilibrium in a thermodynamic framework, based on Gibbs Free Energy Minimization. Models run with the Chassigny meteorite produced the overall highest H2 fugacity. Models reliant on the Rosy Red soil-water analog produced the highest sustained CH4 fugacity (maximum values observed for reactant ALH 77005). In general, Chassigny meteorite protoliths produced the best yield regarding Gibbs Free Energy, from an astrobiological perspective. Occurrences of serpentine and saponite across models are key: these minerals have been observed using CRISM spectral data, and their formation via serpentinization would be consistent with geologically recent-past H2 and CH4 production and sustained energy sources for microbial life. We list index minerals to be used as diagnostic for paleo water-rock models that could have supported geologically recent-past microbial activity, and suggest their application as criteria for future astrobiology study-site selections.
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Affiliation(s)
- Roger Hart
- Department of Physics and Engineering, Community College of Rhode Island, Lincoln, RI 02865, USA
- Department of Geosciences, University of Rhode Island, Kingston, RI 02881, USA;
| | - Dawn Cardace
- Department of Geosciences, University of Rhode Island, Kingston, RI 02881, USA;
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Hanišáková N, Vítězová M, Vítěz T, Kushkevych I, Kotrlová E, Novák D, Lochman J, Zavada R. Microbiological insight into various underground gas storages in Vienna Basin focusing on methanogenic Archaea. Front Microbiol 2023; 14:1293506. [PMID: 38188570 PMCID: PMC10771303 DOI: 10.3389/fmicb.2023.1293506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 11/21/2023] [Indexed: 01/09/2024] Open
Abstract
In recent years, there has been a growing interest in extending the potential of underground gas storage (UGS) facilities to hydrogen and carbon dioxide storage. However, this transition to hydrogen storage raises concerns regarding potential microbial reactions, which could convert hydrogen into methane. It is crucial to gain a comprehensive understanding of the microbial communities within any UGS facilities designated for hydrogen storage. In this study, underground water samples and water samples from surface technologies from 7 different UGS objects located in the Vienna Basin were studied using both molecular biology methods and cultivation methods. Results from 16S rRNA sequencing revealed that the proportion of archaea in the groundwater samples ranged from 20 to 58%, with methanogens being the predominant. Some water samples collected from surface technologies contained up to 87% of methanogens. Various species of methanogens were isolated from individual wells, including Methanobacterium sp., Methanocalculus sp., Methanolobus sp. or Methanosarcina sp. We also examined water samples for the presence of sulfate-reducing bacteria known to be involved in microbially induced corrosion and identified species of the genus Desulfovibrio in the samples. In the second part of our study, we contextualized our data by comparing it to available sequencing data from terrestrial subsurface environments worldwide. This allowed us to discern patterns and correlations between different types of underground samples based on environmental conditions. Our findings reveal presence of methanogens in all analyzed groups of underground samples, which suggests the possibility of unintended microbial hydrogen-to-methane conversion and the associated financial losses. Nevertheless, the prevalence of methanogens in our results also highlights the potential of the UGS environment, which can be effectively leveraged as a bioreactor for the conversion of hydrogen into methane, particularly in the context of Power-to-Methane technology.
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Affiliation(s)
- Nikola Hanišáková
- Section of Microbiology, Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czechia
| | - Monika Vítězová
- Section of Microbiology, Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czechia
| | - Tomáš Vítěz
- Section of Microbiology, Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czechia
- Department of Agricultural, Food and Environmental Engineering, Faculty of AgriSciences, Mendel University in Brno, Brno, Czechia
| | - Ivan Kushkevych
- Section of Microbiology, Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czechia
| | - Eva Kotrlová
- Section of Microbiology, Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czechia
| | - David Novák
- Department of Biochemistry, Faculty of Science, Masaryk University, Brno, Czechia
| | - Jan Lochman
- Department of Biochemistry, Faculty of Science, Masaryk University, Brno, Czechia
| | - Roman Zavada
- Innovation Unit, NAFTA a.s., Bratislava, Slovakia
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Rempfert KR, Kraus EA, Nothaft DB, Dildar N, Spear JR, Sepúlveda J, Templeton AS. Intact polar lipidome and membrane adaptations of microbial communities inhabiting serpentinite-hosted fluids. Front Microbiol 2023; 14:1198786. [PMID: 38029177 PMCID: PMC10667739 DOI: 10.3389/fmicb.2023.1198786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Accepted: 09/25/2023] [Indexed: 12/01/2023] Open
Abstract
The generation of hydrogen and reduced carbon compounds during serpentinization provides sustained energy for microorganisms on Earth, and possibly on other extraterrestrial bodies (e.g., Mars, icy satellites). However, the geochemical conditions that arise from water-rock reaction also challenge the known limits of microbial physiology, such as hyperalkaline pH, limited electron acceptors and inorganic carbon. Because cell membranes act as a primary barrier between a cell and its environment, lipids are a vital component in microbial acclimation to challenging physicochemical conditions. To probe the diversity of cell membrane lipids produced in serpentinizing settings and identify membrane adaptations to this environment, we conducted the first comprehensive intact polar lipid (IPL) biomarker survey of microbial communities inhabiting the subsurface at a terrestrial site of serpentinization. We used an expansive, custom environmental lipid database that expands the application of targeted and untargeted lipodomics in the study of microbial and biogeochemical processes. IPLs extracted from serpentinite-hosted fluid communities were comprised of >90% isoprenoidal and non-isoprenoidal diether glycolipids likely produced by archaeal methanogens and sulfate-reducing bacteria. Phospholipids only constituted ~1% of the intact polar lipidome. In addition to abundant diether glycolipids, betaine and trimethylated-ornithine aminolipids and glycosphingolipids were also detected, indicating pervasive membrane modifications in response to phosphate limitation. The carbon oxidation state of IPL backbones was positively correlated with the reduction potential of fluids, which may signify an energy conservation strategy for lipid synthesis. Together, these data suggest microorganisms inhabiting serpentinites possess a unique combination of membrane adaptations that allow for their survival in polyextreme environments. The persistence of IPLs in fluids beyond the presence of their source organisms, as indicated by 16S rRNA genes and transcripts, is promising for the detection of extinct life in serpentinizing settings through lipid biomarker signatures. These data contribute new insights into the complexity of lipid structures generated in actively serpentinizing environments and provide valuable context to aid in the reconstruction of past microbial activity from fossil lipid records of terrestrial serpentinites and the search for biosignatures elsewhere in our solar system.
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Affiliation(s)
- Kaitlin R. Rempfert
- Department of Geological Sciences, University of Colorado, Boulder, CO, United States
| | - Emily A. Kraus
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO, United States
| | - Daniel B. Nothaft
- Department of Geological Sciences, University of Colorado, Boulder, CO, United States
| | - Nadia Dildar
- Department of Geological Sciences, University of Colorado, Boulder, CO, United States
| | - John R. Spear
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO, United States
- Department of Quantitative Biosciences and Engineering, Colorado School of Mines, Golden, CO, United States
| | - Julio Sepúlveda
- Department of Geological Sciences, University of Colorado, Boulder, CO, United States
| | - Alexis S. Templeton
- Department of Geological Sciences, University of Colorado, Boulder, CO, United States
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Schwander L, Brabender M, Mrnjavac N, Wimmer JLE, Preiner M, Martin WF. Serpentinization as the source of energy, electrons, organics, catalysts, nutrients and pH gradients for the origin of LUCA and life. Front Microbiol 2023; 14:1257597. [PMID: 37854333 PMCID: PMC10581274 DOI: 10.3389/fmicb.2023.1257597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 09/04/2023] [Indexed: 10/20/2023] Open
Abstract
Serpentinization in hydrothermal vents is central to some autotrophic theories for the origin of life because it generates compartments, reductants, catalysts and gradients. During the process of serpentinization, water circulates through hydrothermal systems in the crust where it oxidizes Fe (II) in ultramafic minerals to generate Fe (III) minerals and H2. Molecular hydrogen can, in turn, serve as a freely diffusible source of electrons for the reduction of CO2 to organic compounds, provided that suitable catalysts are present. Using catalysts that are naturally synthesized in hydrothermal vents during serpentinization H2 reduces CO2 to formate, acetate, pyruvate, and methane. These compounds represent the backbone of microbial carbon and energy metabolism in acetogens and methanogens, strictly anaerobic chemolithoautotrophs that use the acetyl-CoA pathway of CO2 fixation and that inhabit serpentinizing environments today. Serpentinization generates reduced carbon, nitrogen and - as newer findings suggest - reduced phosphorous compounds that were likely conducive to the origins process. In addition, it gives rise to inorganic microcompartments and proton gradients of the right polarity and of sufficient magnitude to support chemiosmotic ATP synthesis by the rotor-stator ATP synthase. This would help to explain why the principle of chemiosmotic energy harnessing is more conserved (older) than the machinery to generate ion gradients via pumping coupled to exergonic chemical reactions, which in the case of acetogens and methanogens involve H2-dependent CO2 reduction. Serpentinizing systems exist in terrestrial and deep ocean environments. On the early Earth they were probably more abundant than today. There is evidence that serpentinization once occurred on Mars and is likely still occurring on Saturn's icy moon Enceladus, providing a perspective on serpentinization as a source of reductants, catalysts and chemical disequilibrium for life on other worlds.
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Affiliation(s)
- Loraine Schwander
- Institute of Molecular Evolution, Biology Department, Math. -Nat. Faculty, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Max Brabender
- Institute of Molecular Evolution, Biology Department, Math. -Nat. Faculty, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Natalia Mrnjavac
- Institute of Molecular Evolution, Biology Department, Math. -Nat. Faculty, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Jessica L. E. Wimmer
- Institute of Molecular Evolution, Biology Department, Math. -Nat. Faculty, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Martina Preiner
- Microcosm Earth Center, Max Planck Institute for Terrestrial Microbiology and Philipps-Universität, Marburg, Germany
| | - William F. Martin
- Institute of Molecular Evolution, Biology Department, Math. -Nat. Faculty, Heinrich-Heine-Universität, Düsseldorf, Germany
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He Y, Pan J, Huang D, Sanford RA, Peng S, Wei N, Sun W, Shi L, Jiang Z, Jiang Y, Hu Y, Li S, Li Y, Li M, Dong Y. Distinct microbial structure and metabolic potential shaped by significant environmental gradient impacted by ferrous slag weathering. ENVIRONMENT INTERNATIONAL 2023; 178:108067. [PMID: 37393724 DOI: 10.1016/j.envint.2023.108067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 06/23/2023] [Accepted: 06/25/2023] [Indexed: 07/04/2023]
Abstract
Alkaline ferrous slags pose global environmental issues and long-term risks to ambient environments. To explore the under-investigated microbial structure and biogeochemistry in such unique ecosystems, combined geochemical, microbial, ecological and metagenomic analyses were performed in the areas adjacent to a ferrous slag disposal plant in Sichuan, China. Different levels of exposure to ultrabasic slag leachate had resulted in a significant geochemical gradient of pH (8.0-12.4), electric potential (-126.9 to 437.9 mV), total organic carbon (TOC, 1.5-17.3 mg/L), and total nitrogen (TN, 0.17-1.01 mg/L). Distinct microbial communities were observed depending on their exposure to the strongly alkaline leachate. High pH and Ca2+ concentrations were associated with low microbial diversity and enrichment of bacterial classes Gamma-proteobacteria and Deinococci in the microbial communities exposed to the leachate. Combined metagenomic analyses of 4 leachate-unimpacted and 2-impacted microbial communities led to the assembly of one Serpentinomonas pangenome and 81 phylogenetically diversified metagenome assembled genomes (MAGs). The prevailing taxa in the leachate-impacted habitats (e.g., Serpentinomonas and Meiothermus spp.) were phylogenetically related to those in active serpentinizing ecosystems, suggesting the analogous processes between the man-made and natural systems. More importantly, they accounted for significant abundance of most functional genes associated with environmental adaptation and major element cycling. Their metabolic potential (e.g., cation/H+ antiporters, carbon fixation on lithospheric carbon source, and respiration coupling sulfur oxidization and oxygen or nitrate reduction) may support these taxa to survive and prosper in these unique geochemical niches. This study provides fundamental understandings of the adaptive strategies of microorganisms in response to the strong environmental perturbation by alkali tailings. It also contributes to a better comprehension of how to remediate environments affected by alkaline industrial material.
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Affiliation(s)
- Yu He
- School of Environmental Studies, China University of Geosciences, China
| | - Jie Pan
- Archaeal Biology Center, Institute for Advanced Studies, Shenzhen University, China; Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, China
| | - Dongmei Huang
- School of Environmental Studies, China University of Geosciences, China; Yejin Geological Team of Hubei Geological Bureau, China
| | - Robert A Sanford
- Department of Earth Science & Environmental Change, University of Illinois Urbana-Champaign, Champaign, IL, United States
| | - Shuming Peng
- Institute of Ecological Environment, Chengdu University of Technology, China
| | - Na Wei
- Department of Civil and Environmental Engineering, University of Illinois Urbana-Champaign, Champaign, IL, United States
| | - Weimin Sun
- Guangdong Institute of Eco-environmental and Soil Science, Guangdong, China
| | - Liang Shi
- School of Environmental Studies, China University of Geosciences, China; State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, China; State Environmental Protection Key Laboratory of Source Apportionment and Control of Aquatic Pollution, Ministry of Ecology and Environment, China
| | - Zhou Jiang
- School of Environmental Studies, China University of Geosciences, China
| | - Yongguang Jiang
- School of Environmental Studies, China University of Geosciences, China
| | - Yidan Hu
- School of Environmental Studies, China University of Geosciences, China
| | - Shuyi Li
- School of Environmental Studies, China University of Geosciences, China
| | - Yongzhe Li
- School of Environmental Studies, China University of Geosciences, China
| | - Meng Li
- Archaeal Biology Center, Institute for Advanced Studies, Shenzhen University, China; Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, China.
| | - Yiran Dong
- School of Environmental Studies, China University of Geosciences, China; State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, China; State Environmental Protection Key Laboratory of Source Apportionment and Control of Aquatic Pollution, Ministry of Ecology and Environment, China; Hubei Key Laboratory of Yangtze Catchment Environmental Aquatic Science, China; Hubei Key Laboratory of Wetland Evolution and Ecology Restoration, China.
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9
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Popall RM, Postec A, Lecoeuvre A, Quéméneur M, Erauso G. Metabolic challenges and key players in serpentinite-hosted microbial ecosystems. Front Microbiol 2023; 14:1197823. [PMID: 37555067 PMCID: PMC10404738 DOI: 10.3389/fmicb.2023.1197823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 06/29/2023] [Indexed: 08/10/2023] Open
Abstract
Serpentinite-hosted systems are amongst the most challenging environments for life on Earth. Serpentinization, a geochemical alteration of exposed ultramafic rock, produces hydrothermal fluids enriched in abiotically derived hydrogen (H2), methane (CH4), and small organic molecules. The hyperalkaline pH of these fluids poses a great challenge for metabolic energy and nutrient acquisition, curbing the cellular membrane potential and limiting electron acceptor, carbon, and phosphorous availability. Nevertheless, serpentinization supports the growth of diverse microbial communities whose metabolic make-up might shed light on the beginning of life on Earth and potentially elsewhere. Here, we outline current hypotheses on metabolic energy production, carbon fixation, and nutrient acquisition in serpentinizing environments. A taxonomic survey is performed for each important metabolic function, highlighting potential key players such as H2 and CH4 cycling Serpentinimonas, Hydrogenophaga, Methanobacteriales, Methanosarcinales, and novel candidate phyla. Methodological biases of the available data and future approaches are discussed.
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Affiliation(s)
| | | | | | | | - Gaël Erauso
- Aix-Marseille Univ, Univ Toulon, CNRS, IRD, MIO, Marseille, France
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10
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Quéméneur M, Mei N, Monnin C, Postec A, Guasco S, Jeanpert J, Maurizot P, Pelletier B, Erauso G. Microbial taxa related to natural hydrogen and methane emissions in serpentinite-hosted hyperalkaline springs of New Caledonia. Front Microbiol 2023; 14:1196516. [PMID: 37485525 PMCID: PMC10359428 DOI: 10.3389/fmicb.2023.1196516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 06/20/2023] [Indexed: 07/25/2023] Open
Abstract
The southeastern part of New Caledonia main island (Grande Terre) is the location of a large ophiolitic formation that hosts several hyperalkaline springs discharging high pH (∼11) and warm (<40°C) fluids enriched in methane (CH4) and hydrogen (H2). These waters are produced by the serpentinization of the ultrabasic rock formations. Molecular surveys had previously revealed the prokaryotic diversity of some of these New Caledonian springs, especially from the submarine chimneys of Prony Bay hydrothermal field. Here we investigate the microbial community of hyperalkaline waters from on-land springs and their relationships with elevated concentrations of dissolved H2 (21.1-721.3 μmol/L) and CH4 (153.0-376.6 μmol/L). 16S rRNA gene analyses (metabarcoding and qPCR) provided evidence of abundant and diverse prokaryotic communities inhabiting hyperalkaline fluids at all the collected springs. The abundance of prokaryotes was positively correlated to the H2/CH4 ratio. Prokaryotes consisted mainly of bacteria that use H2 as an energy source, such as microaerophilic Hydrogenophaga/Serpentinimonas (detected in all sources on land) or anaerobic sulfate-reducing Desulfonatronum, which were exclusively found in the most reducing (Eh ref H2 ∼ -700 mV) and the most H2-enriched waters discharging at the intertidal spring of the Bain des Japonais. The relative abundance of a specific group of uncultured Methanosarcinales that thrive in serpentinization-driven ecosystems emitting H2, considered potential H2-consuming methanogens, was positively correlated with CH4 concentrations, and negatively correlated to the relative abundance of methylotrophic Gammaproteobacteria. Firmicutes were also numerous in hyperalkaline waters, and their relative abundance (e.g., Gracilibacter or Dethiobacter) was proportional to the dissolved H2 concentrations, but their role in the H2 budget remains to be assessed. The prokaryotic communities thriving in New Caledonia hyperalkaline waters are similar to those found in other serpentinite-hosted high-pH waters worldwide, such as Lost City (North Atlantic) and The Cedars (California).
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Affiliation(s)
- Marianne Quéméneur
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO, Marseille, France
| | - Nan Mei
- School of Chemistry, Chemical Engineering, and Life Science, Wuhan University of Technology, Wuhan, China
| | - Christophe Monnin
- Géosciences Environnement Toulouse, UMR 5563 (CNRS/UPS/IRD/CNES), Toulouse, France
| | - Anne Postec
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO, Marseille, France
| | - Sophie Guasco
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO, Marseille, France
| | - Julie Jeanpert
- Direction de l’Industrie, des Mines et de l’Energie, Nouméa, New Caledonia
| | - Pierre Maurizot
- Direction de l’Industrie, des Mines et de l’Energie, Nouméa, New Caledonia
| | | | - Gaël Erauso
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO, Marseille, France
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11
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Thieringer PH, Boyd ES, Templeton AS, Spear JR. Metapangenomic investigation provides insight into niche differentiation of methanogenic populations from the subsurface serpentinizing environment, Samail Ophiolite, Oman. Front Microbiol 2023; 14:1205558. [PMID: 37465028 PMCID: PMC10350532 DOI: 10.3389/fmicb.2023.1205558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 06/13/2023] [Indexed: 07/20/2023] Open
Abstract
Serpentinization reactions produce highly reduced waters that have hyperalkaline pH and that can have high concentrations of H2 and CH4. Putatively autotrophic methanogenic archaea have been identified in the subsurface waters of the Samail Ophiolite, Sultanate of Oman, though the strategies to overcome hyperalkaline pH and dissolved inorganic carbon limitation remain to be fully understood. Here, we recovered metagenome assembled genomes (MAGs) and applied a metapangenomic approach to three different Methanobacterium populations to assess habitat-specific functional gene distribution. A Type I population was identified in the fluids with neutral pH, while a Type II and "Mixed" population were identified in the most hyperalkaline fluids (pH 11.63). The core genome of all Methanobacterium populations highlighted potential DNA scavenging techniques to overcome phosphate or nitrogen limitation induced by environmental conditions. With particular emphasis on the Mixed and Type II population found in the most hyperalkaline fluids, the accessory genomes unique to each population reflected adaptation mechanisms suggesting lifestyles that minimize niche overlap. In addition to previously reported metabolic capability to utilize formate as an electron donor and generate intracellular CO2, the Type II population possessed genes relevant to defense against antimicrobials and assimilating potential osmoprotectants to provide cellular stability. The accessory genome of the Mixed population was enriched in genes for multiple glycosyltransferases suggesting reduced energetic costs by adhering to mineral surfaces or to other microorganisms, and fostering a non-motile lifestyle. These results highlight the niche differentiation of distinct Methanobacterium populations to circumvent the challenges of serpentinization impacted fluids through coexistence strategies, supporting our ability to understand controls on methanogenic lifestyles and adaptations within the serpentinizing subsurface fluids of the Samail Ophiolite.
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Affiliation(s)
- Patrick H. Thieringer
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO, United States
| | - Eric S. Boyd
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, United States
| | - Alexis S. Templeton
- Department of Geological Sciences, University of Colorado, Boulder, CO, United States
| | - John R. Spear
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO, United States
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12
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Trutschel LR, Kruger BR, Sackett JD, Chadwick GL, Rowe AR. Determining resident microbial community members and their correlations with geochemistry in a serpentinizing spring. Front Microbiol 2023; 14:1182497. [PMID: 37396382 PMCID: PMC10308030 DOI: 10.3389/fmicb.2023.1182497] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 05/24/2023] [Indexed: 07/04/2023] Open
Abstract
Terrestrial serpentinizing systems allow us insight into the realm of alkaliphilic microbial communities driven by geology in a way that is frequently more accessible than their deep subsurface or marine counterparts. However, these systems are also marked by geochemical and microbial community variation due to the interactions of serpentinized fluids with host geology and the surface environment. To separate the transient from the endemic microbes in a hyperalkaline environment, we assessed the Ney Springs terrestrial serpentinizing system microbial community and geochemistry at six time points over the span of a year. Using 16S rRNA gene surveys we observed 93 amplicon sequence variants (ASVs) that were found at every sampling event. This is compared to ~17,000 transient ASVs that were detected only once across the six sampling events. Of the resident community members, 16 of these ASVs were regularly greater than 1% of the community during every sampling period. Additionally, many of these core taxa experienced statistically significant changes in relative abundance with time. Variation in the abundance of some core populations correlated with geochemical variation. For example, members of the Tindallia group, showed a positive correlation with variation in levels of ammonia at the spring. Investigating the metagenome assembled genomes of these microbes revealed evidence of the potential for ammonia generation via Stickland reactions within Tindallia. This observation offers new insight into the origin of high ammonia concentrations (>70 mg/L) seen at this site. Similarly, the abundance of putative sulfur-oxidizing microbes like Thiomicrospira, Halomonas, and a Rhodobacteraceae species could be linked to changes observed in sulfur-oxidation intermediates like tetrathionate and thiosulfate. While these data supports the influence of core microbial community members on a hyperalkaline spring's geochemistry, there is also evidence that subsurface processes affect geochemistry and may impact community dynamics as well. Though the physiology and ecology of these astrobiologically relevant ecosystems are still being uncovered, this work helps identify a stable microbial community that impacts spring geochemistry in ways not previously observed in serpentinizing ecosystems.
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Affiliation(s)
- Leah R. Trutschel
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, United States
| | - Brittany R. Kruger
- Division of Hydrologic Sciences, Desert Research Institute, Las Vegas, Las Vegas, NV, United States
| | - Joshua D. Sackett
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, United States
| | - Grayson L. Chadwick
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, United States
| | - Annette R. Rowe
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, United States
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Russell MJ. A self-sustaining serpentinization mega-engine feeds the fougerite nanoengines implicated in the emergence of guided metabolism. Front Microbiol 2023; 14:1145915. [PMID: 37275164 PMCID: PMC10236563 DOI: 10.3389/fmicb.2023.1145915] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 03/22/2023] [Indexed: 06/07/2023] Open
Abstract
The demonstration by Ivan Barnes et al. that the serpentinization of fresh Alpine-type ultramafic rocks results in the exhalation of hot alkaline fluids is foundational to the submarine alkaline vent theory (AVT) for life's emergence to its 'improbable' thermodynamic state. In AVT, such alkaline fluids ≤ 150°C, bearing H2 > CH4 > HS--generated and driven convectively by a serpentinizing exothermic mega-engine operating in the ultramafic crust-exhale into the iron-rich, CO2> > > NO3--bearing Hadean ocean to result in hydrothermal precipitate mounds comprising macromolecular ferroferric-carbonate oxyhydroxide and minor sulfide. As the nanocrystalline minerals fougerite/green rust and mackinawite (FeS), they compose the spontaneously precipitated inorganic membranes that keep the highly contrasting solutions apart, thereby maintaining redox and pH disequilibria. They do so in the form of fine chimneys and chemical gardens. The same disequilibria drive the reduction of CO2 to HCOO- or CO, and the oxidation of CH4 to a methyl group-the two products reacting to form acetate in a sequence antedating the 'energy-producing' acetyl coenzyme-A pathway. Fougerite is a 2D-layered mineral in which the hydrous interlayers themselves harbor 2D solutions, in effect constricted to ~ 1D by preferentially directed electron hopping/tunneling, and proton Gröthuss 'bucket-brigading' when subject to charge. As a redox-driven nanoengine or peristaltic pump, fougerite forces the ordered reduction of nitrate to ammonium, the amination of pyruvate and oxalate to alanine and glycine, and their condensation to short peptides. In turn, these peptides have the flexibility to sequester the founding inorganic iron oxyhydroxide, sulfide, and pyrophosphate clusters, to produce metal- and phosphate-dosed organic films and cells. As the feed to the hydrothermal mound fails, the only equivalent sustenance on offer to the first autotrophs is the still mildly serpentinizing upper crust beneath. While the conditions here are very much less bountiful, they do offer the similar feed and disequilibria the survivors are accustomed to. Sometime during this transition, a replicating non-ribosomal guidance system is discovered to provide the rules to take on the incrementally changing surroundings. The details of how these replicating apparatuses emerged are the hard problem, but by doing so the progenote archaea and bacteria could begin to colonize what would become the deep biosphere. Indeed, that the anaerobic nitrate-respiring methanotrophic archaea and the deep-branching Acetothermia presently comprise a portion of that microbiome occupying serpentinizing rocks offers circumstantial support for this notion. However, the inescapable, if jarring conclusion is drawn that, absent fougerite/green rust, there would be no structured channelway to life.
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Affiliation(s)
- Michael J. Russell
- Dipartimento di Chimica, Università degli Studi di Torino, Torino, Italy
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14
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Howells AEG, De Martini F, Gile GH, Shock EL. An examination of protist diversity in serpentinization-hosted ecosystems of the Samail Ophiolite of Oman. Front Microbiol 2023; 14:1139333. [PMID: 37213519 PMCID: PMC10192764 DOI: 10.3389/fmicb.2023.1139333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 03/30/2023] [Indexed: 05/23/2023] Open
Abstract
In the Samail Ophiolite of Oman, the geological process of serpentinization produces reduced, hydrogen rich, hyperalkaline (pH > 11) fluids. These fluids are generated through water reacting with ultramafic rock from the upper mantle in the subsurface. On Earth's continents, serpentinized fluids can be expressed at the surface where they can mix with circumneutral surface water and subsequently generate a pH gradient (∼pH 8 to pH > 11) in addition to variations in other chemical parameters such as dissolved CO2, O2, and H2. Globally, archaeal and bacterial community diversity has been shown to reflect geochemical gradients established by the process of serpentinization. It is unknown if the same is true for microorganisms of the domain Eukarya (eukaryotes). In this study, using 18S rRNA gene amplicon sequencing, we explore the diversity of microbial eukaryotes called protists in sediments of serpentinized fluids in Oman. We demonstrate that protist community composition and diversity correlate significantly with variations in pH, with protist richness being significantly lower in sediments of hyperalkaline fluids. In addition to pH, the availability of CO2 to phototrophic protists, the composition of potential food sources (prokaryotes) for heterotrophic protists and the concentration of O2 for anaerobic protists are factors that likely shape overall protist community composition and diversity along the geochemical gradient. The taxonomy of the protist 18S rRNA gene sequences indicates the presence of protists that are involved in carbon cycling in serpentinized fluids of Oman. Therefore, as we evaluate the applicability of serpentinization for carbon sequestration, the presence and diversity of protists should be considered.
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Affiliation(s)
- Alta E. G. Howells
- School of Life Sciences, Arizona State University, Tempe, AZ, United States
| | - Francesca De Martini
- School of Life Sciences, Arizona State University, Tempe, AZ, United States
- Mesa Community College, Mesa, AZ, United States
| | - Gillian H. Gile
- School of Life Sciences, Arizona State University, Tempe, AZ, United States
- Biodesign Center for Fundamental and Applied Microbiomics, Arizona State University, Tempe, AZ, United States
| | - Everett L. Shock
- Biodesign Center for Fundamental and Applied Microbiomics, Arizona State University, Tempe, AZ, United States
- School of Molecular Sciences, Arizona State University, Tempe, AZ, United States
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ, United States
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15
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Seyler LM, Kraus EA, McLean C, Spear JR, Templeton AS, Schrenk MO. An untargeted exometabolomics approach to characterize dissolved organic matter in groundwater of the Samail Ophiolite. Front Microbiol 2023; 14:1093372. [PMID: 36970670 PMCID: PMC10033605 DOI: 10.3389/fmicb.2023.1093372] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 01/23/2023] [Indexed: 03/11/2023] Open
Abstract
The process of serpentinization supports life on Earth and gives rise to the habitability of other worlds in our Solar System. While numerous studies have provided clues to the survival strategies of microbial communities in serpentinizing environments on the modern Earth, characterizing microbial activity in such environments remains challenging due to low biomass and extreme conditions. Here, we used an untargeted metabolomics approach to characterize dissolved organic matter in groundwater in the Samail Ophiolite, the largest and best characterized example of actively serpentinizing uplifted ocean crust and mantle. We found that dissolved organic matter composition is strongly correlated with both fluid type and microbial community composition, and that the fluids that were most influenced by serpentinization contained the greatest number of unique compounds, none of which could be identified using the current metabolite databases. Using metabolomics in conjunction with metagenomic data, we detected numerous products and intermediates of microbial metabolic processes and identified potential biosignatures of microbial activity, including pigments, porphyrins, quinones, fatty acids, and metabolites involved in methanogenesis. Metabolomics techniques like the ones used in this study may be used to further our understanding of life in serpentinizing environments, and aid in the identification of biosignatures that can be used to search for life in serpentinizing systems on other worlds.
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Affiliation(s)
- Lauren M. Seyler
- Department of Earth and Environmental Sciences, Michigan State University, East Lansing, MI, United States
- Biology Program, School of Natural Sciences and Mathematics, Stockton University, Galloway, NJ, United States
- Blue Marble Space Institute of Science, Seattle, WA, United States
- *Correspondence: Lauren M. Seyler,
| | - Emily A. Kraus
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO, United States
- Department of Environmental Engineering, University of Colorado, Boulder, Boulder, CO, United States
| | - Craig McLean
- Massachusetts Institute of Technology, Cambridge, MA, United States
| | - John R. Spear
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO, United States
| | - Alexis S. Templeton
- Department of Geological Sciences, University of Colorado, Boulder, Boulder, CO, United States
| | - Matthew O. Schrenk
- Department of Earth and Environmental Sciences, Michigan State University, East Lansing, MI, United States
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, United States
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16
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Amils R, Escudero C, Oggerin M, Puente Sánchez F, Arce Rodríguez A, Fernández Remolar D, Rodríguez N, García Villadangos M, Sanz JL, Briones C, Sánchez-Román M, Gómez F, Leandro T, Moreno-Paz M, Prieto-Ballesteros O, Molina A, Tornos F, Sánchez-Andrea I, Timmis K, Pieper DH, Parro V. Coupled C, H, N, S and Fe biogeochemical cycles operating in the continental deep subsurface of the Iberian Pyrite Belt. Environ Microbiol 2023; 25:428-453. [PMID: 36453153 PMCID: PMC10107794 DOI: 10.1111/1462-2920.16291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 11/23/2022] [Indexed: 12/03/2022]
Abstract
Microbial activity is a major contributor to the biogeochemical cycles that make up the life support system of planet Earth. A 613 m deep geomicrobiological perforation and a systematic multi-analytical characterization revealed an unexpected diversity associated with the rock matrix microbiome that operates in the subsurface of the Iberian Pyrite Belt (IPB). Members of 1 class and 16 genera were deemed the most representative microorganisms of the IPB deep subsurface and selected for a deeper analysis. The use of fluorescence in situ hybridization allowed not only the identification of microorganisms but also the detection of novel activities in the subsurface such as anaerobic ammonium oxidation (ANAMMOX) and anaerobic methane oxidation, the co-occurrence of microorganisms able to maintain complementary metabolic activities and the existence of biofilms. The use of enrichment cultures sensed the presence of five different complementary metabolic activities along the length of the borehole and isolated 29 bacterial species. Genomic analysis of nine isolates identified the genes involved in the complete operation of the light-independent coupled C, H, N, S and Fe biogeochemical cycles. This study revealed the importance of nitrate reduction microorganisms in the oxidation of iron in the anoxic conditions existing in the subsurface of the IPB.
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Affiliation(s)
- Ricardo Amils
- Centro de Astrobiología (CSIC-INTA), Torrejón de Ardoz, Spain
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Universidad Autónoma de Madrid, Madrid, Spain
| | - Cristina Escudero
- Centro de Astrobiología (CSIC-INTA), Torrejón de Ardoz, Spain
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Universidad Autónoma de Madrid, Madrid, Spain
| | - Monike Oggerin
- Centro de Astrobiología (CSIC-INTA), Torrejón de Ardoz, Spain
| | | | - Alejandro Arce Rodríguez
- Institute of Microbiology, Technical University Braunschweig, Germany
- Microbial Interactions and Processes Research Group, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | | | - Nuria Rodríguez
- Centro de Astrobiología (CSIC-INTA), Torrejón de Ardoz, Spain
| | | | - José Luis Sanz
- Department of Molecular Biology, Universidad Autónoma de Madrid, Madrid, Spain
| | - Carlos Briones
- Centro de Astrobiología (CSIC-INTA), Torrejón de Ardoz, Spain
| | | | - Felipe Gómez
- Centro de Astrobiología (CSIC-INTA), Torrejón de Ardoz, Spain
| | - Tania Leandro
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Universidad Autónoma de Madrid, Madrid, Spain
| | | | | | - Antonio Molina
- Centro de Astrobiología (CSIC-INTA), Torrejón de Ardoz, Spain
| | - Fernando Tornos
- Centro de Astrobiología (CSIC-INTA), Torrejón de Ardoz, Spain
| | | | - Kenneth Timmis
- Institute of Microbiology, Technical University Braunschweig, Germany
| | - Dietmar H Pieper
- Microbial Interactions and Processes Research Group, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Victor Parro
- Centro de Astrobiología (CSIC-INTA), Torrejón de Ardoz, Spain
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17
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Rempfert KR, Nothaft DB, Kraus EA, Asamoto CK, Evans RD, Spear JR, Matter JM, Kopf SH, Templeton AS. Subsurface biogeochemical cycling of nitrogen in the actively serpentinizing Samail Ophiolite, Oman. Front Microbiol 2023; 14:1139633. [PMID: 37152731 PMCID: PMC10160414 DOI: 10.3389/fmicb.2023.1139633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2023] [Accepted: 03/15/2023] [Indexed: 05/09/2023] Open
Abstract
Nitrogen (N) is an essential element for life. N compounds such as ammonium ( NH 4 + ) may act as electron donors, while nitrate ( NO 3 - ) and nitrite ( NO 2 - ) may serve as electron acceptors to support energy metabolism. However, little is known regarding the availability and forms of N in subsurface ecosystems, particularly in serpentinite-hosted settings where hydrogen (H2) generated through water-rock reactions promotes habitable conditions for microbial life. Here, we analyzed N and oxygen (O) isotope composition to investigate the source, abundance, and cycling of N species within the Samail Ophiolite of Oman. The dominant dissolved N species was dependent on the fluid type, with Mg2+- HCO 3 - type fluids comprised mostly of NO 3 - , and Ca2+-OH- fluids comprised primarily of ammonia (NH3). We infer that fixed N is introduced to the serpentinite aquifer as NO 3 - . High concentrations of NO 3 - (>100 μM) with a relict meteoric oxygen isotopic composition (δ18O ~ 22‰, Δ17O ~ 6‰) were observed in shallow aquifer fluids, indicative of NO 3 - sourced from atmospheric deposition (rainwater NO 3 - : δ18O of 53.7‰, Δ17O of 16.8‰) mixed with NO 3 - produced in situ through nitrification (estimated endmember δ18O and Δ17O of ~0‰). Conversely, highly reacted hyperalkaline fluids had high concentrations of NH3 (>100 μM) with little NO 3 - detectable. We interpret that NH3 in hyperalkaline fluids is a product of NO 3 - reduction. The proportionality of the O and N isotope fractionation (18ε / 15ε) measured in Samail Ophiolite NO 3 - was close to unity (18ε / 15ε ~ 1), which is consistent with dissimilatory NO 3 - reduction with a membrane-bound reductase (NarG); however, abiotic reduction processes may also be occurring. The presence of genes commonly involved in N reduction processes (narG, napA, nrfA) in the metagenomes of biomass sourced from aquifer fluids supports potential biological involvement in the consumption of NO 3 - . Production of NH 4 + as the end-product of NO 3 - reduction via dissimilatory nitrate reduction to ammonium (DNRA) could retain N in the subsurface and fuel nitrification in the oxygenated near surface. Elevated bioavailable N in all sampled fluids indicates that N is not likely limiting as a nutrient in serpentinites of the Samail Ophiolite.
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Affiliation(s)
- Kaitlin R. Rempfert
- Department of Geological Sciences, University of Colorado, Boulder, CO, United States
- *Correspondence: Kaitlin R. Rempfert
| | - Daniel B. Nothaft
- Department of Geological Sciences, University of Colorado, Boulder, CO, United States
| | - Emily A. Kraus
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO, United States
| | - Ciara K. Asamoto
- Department of Geological Sciences, University of Colorado, Boulder, CO, United States
| | - R. Dave Evans
- School of Biological Sciences, Washington State University, Pullman, WA, United States
| | - John R. Spear
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO, United States
- Quantitative Biosciences and Engineering, Colorado School of Mines, Golden, CO, United States
| | - Juerg M. Matter
- National Oceanography Centre, University of Southampton, Southampton, United Kingdom
| | - Sebastian H. Kopf
- Department of Geological Sciences, University of Colorado, Boulder, CO, United States
| | - Alexis S. Templeton
- Department of Geological Sciences, University of Colorado, Boulder, CO, United States
- Alexis S. Templeton
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18
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Munro-Ehrlich M, Nothaft DB, Fones EM, Matter JM, Templeton AS, Boyd ES. Parapatric speciation of Meiothermus in serpentinite-hosted aquifers in Oman. Front Microbiol 2023; 14:1138656. [PMID: 37125170 PMCID: PMC10130571 DOI: 10.3389/fmicb.2023.1138656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 03/27/2023] [Indexed: 05/02/2023] Open
Abstract
The factors that control the distribution and evolution of microbial life in subsurface environments remain enigmatic due to challenges associated with sampling fluids from discrete depth intervals via boreholes while avoiding mixing of fluids. Here, using an inflatable packer system, fracture waters were isolated and collected from three discrete depth intervals spanning >130 m in a borehole intersecting an ultramafic rock formation undergoing serpentinization in the Samail Ophiolite, Sultanate of Oman. Near surface aquifer waters were moderately reducing and had alkaline pH while deeper aquifer waters were reduced and had hyperalkaline pH, indicating extensive influence by serpentinization. Metagenomic sequencing and analysis of DNA from filtered biomass collected from discrete depth intervals revealed an abundance of aerobes in near surface waters and a greater proportion of anaerobes at depth. Yet the abundance of the putatively obligate aerobe, Meiothermus, increased with depth, providing an opportunity to evaluate the influence of chemical and spatial variation on its distribution and speciation. Two clades of Meiothermus metagenome assembled genomes (MAGs) were identified that correspond to surface and deep populations termed Types I (S) and II (D), respectively; both clades comprised an apparently Oman-specific lineage indicating a common ancestor. Type II (D) clade MAGs encoded fewer genes and were undergoing slower genome replication as inferred from read mapping. Further, single nucleotide variants (SNVs) and mobile genetic elements identified among MAGs revealed detectable, albeit limited, evidence for gene flow/recombination between spatially segregated Type I (S) and Type II (D) populations. Together, these observations indicate that chemical variation generated by serpentinization, combined with physical barriers that reduce/limit dispersal and gene flow, allowed for the parapatric speciation of Meiothermus in the Samail Ophiolite or a geologic precursor. Further, Meiothermus genomic data suggest that deep and shallow aquifer fluids in the Samail Ophiolite may mix over shorter time scales than has been previously estimated from geochemical data.
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Affiliation(s)
- Mason Munro-Ehrlich
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, United States
| | - Daniel B. Nothaft
- Department of Geosciences, University of Colorado, Boulder, Boulder, CO, United States
| | - Elizabeth M. Fones
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, United States
| | - Juerg M. Matter
- School of Ocean and Earth Science, University of Southampton, Southampton, United Kingdom
| | - Alexis S. Templeton
- Department of Geosciences, University of Colorado, Boulder, Boulder, CO, United States
| | - Eric S. Boyd
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, United States
- *Correspondence: Eric S. Boyd,
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Narrowing gaps between Earth and life. Proc Natl Acad Sci U S A 2022; 119:e2216017119. [PMID: 36288265 PMCID: PMC9674954 DOI: 10.1073/pnas.2216017119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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20
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Wynne JJ, Titus TN, Agha‐Mohammadi A, Azua‐Bustos A, Boston PJ, de León P, Demirel‐Floyd C, De Waele J, Jones H, Malaska MJ, Miller AZ, Sapers HM, Sauro F, Sonderegger DL, Uckert K, Wong UY, Alexander EC, Chiao L, Cushing GE, DeDecker J, Fairén AG, Frumkin A, Harris GL, Kearney ML, Kerber L, Léveillé RJ, Manyapu K, Massironi M, Mylroie JE, Onac BP, Parazynski SE, Phillips‐Lander CM, Prettyman TH, Schulze‐Makuch D, Wagner RV, Whittaker WL, Williams KE. Fundamental Science and Engineering Questions in Planetary Cave Exploration. JOURNAL OF GEOPHYSICAL RESEARCH. PLANETS 2022; 127:e2022JE007194. [PMID: 36582809 PMCID: PMC9787064 DOI: 10.1029/2022je007194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 04/21/2022] [Accepted: 04/22/2022] [Indexed: 06/17/2023]
Abstract
Nearly half a century ago, two papers postulated the likelihood of lunar lava tube caves using mathematical models. Today, armed with an array of orbiting and fly-by satellites and survey instrumentation, we have now acquired cave data across our solar system-including the identification of potential cave entrances on the Moon, Mars, and at least nine other planetary bodies. These discoveries gave rise to the study of planetary caves. To help advance this field, we leveraged the expertise of an interdisciplinary group to identify a strategy to explore caves beyond Earth. Focusing primarily on astrobiology, the cave environment, geology, robotics, instrumentation, and human exploration, our goal was to produce a framework to guide this subdiscipline through at least the next decade. To do this, we first assembled a list of 198 science and engineering questions. Then, through a series of social surveys, 114 scientists and engineers winnowed down the list to the top 53 highest priority questions. This exercise resulted in identifying emerging and crucial research areas that require robust development to ultimately support a robotic mission to a planetary cave-principally the Moon and/or Mars. With the necessary financial investment and institutional support, the research and technological development required to achieve these necessary advancements over the next decade are attainable. Subsequently, we will be positioned to robotically examine lunar caves and search for evidence of life within Martian caves; in turn, this will set the stage for human exploration and potential habitation of both the lunar and Martian subsurface.
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Affiliation(s)
- J. Judson Wynne
- Department of Biological Sciences and Center for Adaptable Western LandscapesNorthern Arizona UniversityFlagstaffAZUSA
| | | | | | - Armando Azua‐Bustos
- Centro de AstrobiologíaCSIC‐INTAUnidad María de MaeztuInstituto Nacional de Técnica Aeroespacial Ctra de Torrejón a AjalvirMadridSpain
- Instituto de Ciencias BiomédicasFacultad de Ciencias de la SaludUniversidad Autónoma de ChileSantiagoChile
| | | | - Pablo de León
- Human Spaceflight LaboratoryDepartment of Space StudiesUniversity of North DakotaGrand ForksNDUSA
| | | | - Jo De Waele
- Department of Biological, Geological and Environmental SciencesUniversity of BolognaBolognaItaly
| | - Heather Jones
- Robotics InstituteCarnegie Mellon UniversityPittsburghPAUSA
| | - Michael J. Malaska
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - Ana Z. Miller
- Laboratório HERCULESUniversity of ÉvoraÉvoraPortugal
- Instituto de Recursos Naturales y AgrobiologíaConsejo Superior de Investigaciones CientíficasSevilleSpain
| | - Haley M. Sapers
- Department of Earth and Space Science and EngineeringYork UniversityTorontoONCanada
| | - Francesco Sauro
- Department of Biological, Geological and Environmental SciencesUniversity of BolognaBolognaItaly
| | - Derek L. Sonderegger
- Department of Mathematics and StatisticsNorthern Arizona UniversityFlagstaffAZUSA
| | - Kyle Uckert
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | | | - E. Calvin Alexander
- Earth and Environmental Sciences DepartmentUniversity of MinnesotaMinneapolisMNUSA
| | - Leroy Chiao
- Department of Mechanical EngineeringRice UniversityHoustonTXUSA
| | - Glen E. Cushing
- U.S. Geological SurveyAstrogeology Science CenterFlagstaffAZUSA
| | - John DeDecker
- Center for Mineral Resources ScienceColorado School of MinesGoldenCOUSA
| | - Alberto G. Fairén
- Centro de AstrobiologíaCSIC‐INTAUnidad María de MaeztuInstituto Nacional de Técnica Aeroespacial Ctra de Torrejón a AjalvirMadridSpain
- Department of AstronomyCornell UniversityIthacaNYUSA
| | - Amos Frumkin
- Institute of Earth SciencesThe Hebrew UniversityJerusalemIsrael
| | - Gary L. Harris
- Human Spaceflight LaboratoryDepartment of Space StudiesUniversity of North DakotaGrand ForksNDUSA
| | - Michelle L. Kearney
- Department of Astronomy and Planetary SciencesNorthern Arizona UniversityFlagstaffAZUSA
| | - Laura Kerber
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - Richard J. Léveillé
- Department of Earth and Planetary SciencesMcGill UniversityMontrealQCCanada
- Geosciences DepartmentJohn Abbott CollegeSte‐Anne‐de‐BellevueQCCanada
| | | | - Matteo Massironi
- Dipartimento di GeoscienzeUniversità degli Studi di PadovaPadovaItaly
| | - John E. Mylroie
- Department of GeosciencesMississippi State UniversityStarkvilleMSUSA
| | - Bogdan P. Onac
- School of GeosciencesUniversity of South FloridaTampaFLUSA
- Emil G. Racoviță InstituteBabeș‐Bolyai UniversityCluj‐NapocaRomania
| | | | | | | | - Dirk Schulze‐Makuch
- Astrobiology GroupCenter of Astronomy and AstrophysicsTechnische Universität BerlinBerlinGermany
- Section GeomicrobiologyGFZ German Research Centre for GeosciencesPotsdamGermany
- Department of Experimental LimnologyLeibniz‐Institute of Freshwater Ecology and Inland Fisheries (IGB)StechlinGermany
| | - Robert V. Wagner
- School of Earth and Space ExplorationArizona State UniversityTempeAZUSA
| | - William L. Whittaker
- Department of Biological, Geological and Environmental SciencesUniversity of BolognaBolognaItaly
| | - Kaj E. Williams
- U.S. Geological SurveyAstrogeology Science CenterFlagstaffAZUSA
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Abstract
Little is known of acetogens in contemporary serpentinizing systems, despite widely supported theories that serpentinite-hosted environments supported the first life on Earth via acetogenesis. To address this knowledge gap, genome-resolved metagenomics was applied to subsurface fracture water communities from an area of active serpentinization in the Samail Ophiolite, Sultanate of Oman. Two deeply branching putative bacterial acetogen types were identified in the communities belonging to the Acetothermia (hereafter, types I and II) that exhibited distinct distributions among waters with lower and higher water-rock reaction (i.e., serpentinization influence), respectively. Metabolic reconstructions revealed contrasting core metabolic pathways of type I and II Acetothermia, including in acetogenic pathway components (e.g., bacterial- vs. archaeal-like carbon monoxide dehydrogenases [CODH], respectively), hydrogen use to drive acetogenesis, and chemiosmotic potential generation via respiratory (type I) or canonical acetogen ferredoxin-based complexes (type II). Notably, type II Acetothermia metabolic pathways allow for use of serpentinization-derived substrates and implicate them as key primary producers in contemporary hyperalkaline serpentinite environments. Phylogenomic analyses indicate that 1) archaeal-like CODH of the type II genomes and those of other serpentinite-associated Bacteria derive from a deeply rooted horizontal transfer or origin among archaeal methanogens and 2) Acetothermia are among the earliest evolving bacterial lineages. The discovery of dominant and early-branching acetogens in subsurface waters of the largest near-surface serpentinite formation provides insight into the physiological traits that likely facilitated rock-supported life to flourish on a primitive Earth and possibly on other rocky planets undergoing serpentinization.
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22
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Mei N, Postec A, Bartoli M, Vandecasteele C, Wils L, Gil L, Monnin C, Pelletier B, Erauso G, Quéméneur M. Methanobacterium alkalithermotolerans sp. nov., a novel alkaliphilic and hydrogen-utilizing methanogen isolated from an alkaline geothermal spring (La Crouen, New Caledonia). Int J Syst Evol Microbiol 2022; 72. [PMID: 36260502 DOI: 10.1099/ijsem.0.005554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023] Open
Abstract
An anaerobic, hydrogenotrophic methane-producing archaeon was isolated from an alkaline thermal spring (42 °C, pH 9.0) in New Caledonia. This methanogen, designated strain CANT, is alkaliphilic, thermotolerant, with Gram-positive staining non-motile cells. Strain CANT grows autotrophically using hydrogen exclusively as an energy source and carbon dioxide as the sole carbon source (without the requirement of yeast extract or other organic compounds). It grows at 20-45 °C (optimum, 45 °C) and pH 7.3-9.7 (optimum, pH 9.0). NaCl is not required for growth (optimum 0 %) but is tolerated up to 1.5 %. It resists novobiocin, streptomycin and vancomycin but is inhibited by ampicillin and penicillin, among other antibiotics. The genome consists of a circular chromosome (2.2 Mb) containing 2126 predicted protein-encoding genes with a G+C content of 36.4 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain CANT is a member of the genus Methanobacterium, most closely related to the alkaliphilic Methanobacterium alcaliphilum WeN4T with 98.5 % 16S rRNA gene sequence identity. The genomes of strain CANT and M. alcaliphilum DSM 3459, sequenced in this study, share 71.6 % average nucleotide identity and 14.0 % digital DNA-DNA hybridization. Therefore, phylogenetic and physiological results indicate that strain CANT represents a novel species, for which the name Methanobacterium alkalithermotolerans sp. nov. is proposed, and strain CANT (=DSM 102889T= JCM 31304T) is assigned as the type strain.
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Affiliation(s)
- Nan Mei
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO, Marseille, France
- Present address: School of Chemistry, Chemical Engineering, and Life Science, Wuhan University of Technology, Wuhan 430070, PR China
| | - Anne Postec
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO, Marseille, France
| | - Manon Bartoli
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO, Marseille, France
| | | | - Laura Wils
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO, Marseille, France
| | - Lisa Gil
- INRAE, US 1426, GeT-PlaGe, Genotoul, Castanet-Tolosan, France
| | - Christophe Monnin
- GET UMR5563 (CNRS/UPS/IRD/CNES), Géosciences Environnement Toulouse, 14 Avenue Edouard Belin, 31400 Toulouse, France
| | - Bernard Pelletier
- UMR Géoazur, Centre IRD de Nouméa, 101 Promenade Roger Laroque, BP A5 - 98848 Nouméa cedex, New Caledonia
| | - Gael Erauso
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO, Marseille, France
| | - Marianne Quéméneur
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO, Marseille, France
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Abstract
Alkaline fluids venting from chimneys of the Lost City hydrothermal field flow from a potentially vast microbial habitat within the seafloor where energy and organic molecules are released by chemical reactions within rocks uplifted from Earth's mantle. In this study, we investigated hydrothermal fluids venting from Lost City chimneys as windows into subseafloor environments where the products of geochemical reactions, such as molecular hydrogen (H2), formate, and methane, may be the only available sources of energy for biological activity. Our deep sequencing of metagenomes and metatranscriptomes from these hydrothermal fluids revealed a few key species of archaea and bacteria that are likely to play critical roles in the subseafloor microbial ecosystem. We identified a population of Thermodesulfovibrionales (belonging to phylum Nitrospirota) as a prevalent sulfate-reducing bacterium that may be responsible for much of the consumption of H2 and sulfate in Lost City fluids. Metagenome-assembled genomes (MAGs) classified as Methanosarcinaceae and Candidatus Bipolaricaulota were also recovered from venting fluids and represent potential methanogenic and acetogenic members of the subseafloor ecosystem. These genomes share novel hydrogenases and formate dehydrogenase-like sequences that may be unique to hydrothermal environments where H2 and formate are much more abundant than carbon dioxide. The results of this study include multiple examples of metabolic strategies that appear to be advantageous in hydrothermal and subsurface alkaline environments where energy and carbon are provided by geochemical reactions. IMPORTANCE The Lost City hydrothermal field is an iconic example of a microbial ecosystem fueled by energy and carbon from Earth's mantle. Uplift of mantle rocks into the seafloor can trigger a process known as serpentinization that releases molecular hydrogen (H2) and creates unusual environmental conditions where simple organic carbon molecules are more stable than dissolved inorganic carbon. This study provides an initial glimpse into the kinds of microbes that live deep within the seafloor where serpentinization takes place, by sampling hydrothermal fluids exiting from the Lost City chimneys. The metabolic strategies that these microbes appear to be using are also shared by microbes that inhabit other sites of serpentinization, including continental subsurface environments and natural springs. Therefore, the results of this study contribute to a broader, interdisciplinary effort to understand the general principles and mechanisms by which serpentinization-associated processes can support life on Earth and perhaps other worlds.
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Cardenas Gomez K, Rose A, Gibb KS, Christian KA. Microbial communities associated with mounds of the Orange-footed scrubfowl Megapodius reinwardt. PeerJ 2022; 10:e13600. [PMID: 35910771 PMCID: PMC9332330 DOI: 10.7717/peerj.13600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 05/26/2022] [Indexed: 01/17/2023] Open
Abstract
Megapodius reinwardt, the orange-footed scrubfowl, belongs to a small family of birds that inhabits the Indo-Australian region. Megapodes are unique in incubating their eggs in mounds using heat from microbial decomposition of organic materials and solar radiation. Little is known about the microorganisms involved in the decomposition of organic matter in mounds. To determine the source of microbes in the mounds, we used 16S and 18S rRNA gene sequencing to characterize the microbial communities of mound soil, adjacent soil and scrubfowl faeces. We found that the microbial communities of scrubfowl faeces were substantially different from those of the mounds and surrounding soils, suggesting that scrubfowls probably do not use their faeces to inoculate their mounds although a few microbial sequence variants were present in both faeces and mound samples. Further, the mound microbial community structure was significantly different to the adjacent soils. For example, mounds had a high relative abundance of sequence variants belonging to Thermomonosporaceae, a thermophilic soil bacteria family able to degrade cellulose from plant residues. It is not clear whether members of Thermomonosporaceae disproportionately contribute to the generation of heat in the mound, or whether they simply thrive in the warm mound environment created by the metabolic activity of the mound microbial community. The lack of clarity in the literature between designations of heat-producing (thermogenic) and heat-thriving (thermophilic) microbes poses a challenge to understanding the role of specific bacteria and fungi in incubation.
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Meyer-Dombard DR, Malas J. Advances in Defining Ecosystem Functions of the Terrestrial Subsurface Biosphere. Front Microbiol 2022; 13:891528. [PMID: 35722320 PMCID: PMC9201636 DOI: 10.3389/fmicb.2022.891528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 05/03/2022] [Indexed: 11/13/2022] Open
Abstract
The subsurface is one of the last remaining 'uncharted territories' of Earth and is now accepted as a biosphere in its own right, at least as critical to Earth systems as the surface biosphere. The terrestrial deep biosphere is connected through a thin veneer of Earth's crust to the surface biosphere, and many subsurface biosphere ecosystems are impacted by surface topography, climate, and near surface groundwater movement and represent a transition zone (at least ephemerally). Delving below this transition zone, we can examine how microbial metabolic functions define a deep terrestrial subsurface. This review provides a survey of the most recent advances in discovering the functional and genomic diversity of the terrestrial subsurface biosphere, how microbes interact with minerals and obtain energy and carbon in the subsurface, and considers adaptations to the presented environmental extremes. We highlight the deepest subsurface studies in deep mines, deep laboratories, and boreholes in crystalline and altered host rock lithologies, with a focus on advances in understanding ecosystem functions in a holistic manner.
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26
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Fones EM, Templeton AS, Mogk DW, Boyd ES. Transformation of low molecular weight organic acids by microbial endoliths in subsurface mafic and ultramafic igneous rock. Environ Microbiol 2022; 24:4137-4152. [PMID: 35590457 DOI: 10.1111/1462-2920.16041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 04/13/2022] [Accepted: 05/05/2022] [Indexed: 11/28/2022]
Abstract
A growing body of work indicates that continental subsurface rocks host a substantial portion of the Earth's biosphere. However, the activities of microbial cells inhabiting pore spaces and microfractures in subsurface rocks remain underexplored. Here, we develop and optimize microcosm assays to detect organic acid transformation activities of cells residing in mafic to ultramafic igneous rocks. Application of this assay to gabbro core from the Stillwater Mine, Montana, USA, revealed maximal methane production from acetate at temperatures approximating that of the mine. Controls show that these activities are not due to contamination introduced during drilling, exhumation, or laboratory processing of the core. The assay was then applied to rocks cored from the Samail Ophiolite, Oman, which is undergoing low temperature serpentinization. Production of i) carbon dioxide from acetate and formate and ii) methane from formate were detected in a dunite/harzburgite rock core interfacing pH 9.6 waters, and estimates of microbial activities were up to three orders of magnitude higher in the rock core pore space than in corresponding waters. The detection of endolithic microbial activities in igneous rocks has implications for life detection on other planetary bodies where similar rock types prevail, such as Mars, Europa, and Enceladus. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Elizabeth M Fones
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, 59717
| | - Alexis S Templeton
- Department of Geological Sciences, University of Colorado, Boulder, CO, 80309
| | - David W Mogk
- Department of Earth Sciences, Montana State University, Bozeman, MT, 59717
| | - Eric S Boyd
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, 59717
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Thieringer PH, Honeyman AS, Spear JR. Spatial and Temporal Constraints on the Composition of Microbial Communities in Subsurface Boreholes of the Edgar Experimental Mine. Microbiol Spectr 2021; 9:e0063121. [PMID: 34756066 PMCID: PMC8579930 DOI: 10.1128/spectrum.00631-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 10/07/2021] [Indexed: 12/14/2022] Open
Abstract
The deep biosphere hosts uniquely adapted microorganisms overcoming geochemical extremes at significant depths within the crust of the Earth. Attention is required to understand the near subsurface and its continuity with surface systems, where numerous novel microbial members with unique physiological modifications remain to be identified. This surface-subsurface relationship raises key questions about networking of surface hydrology, geochemistry affecting near-subsurface microbial composition, and resiliency of subsurface ecosystems. Here, we apply molecular and geochemical approaches to determine temporal microbial composition and environmental conditions of filtered borehole fluid from the Edgar Experimental Mine (∼150 m below the surface) in Idaho Springs, CO. Samples were collected over a 4-year collection period from expandable packers deployed to accumulate fluid in previously drilled boreholes located centimeters to meters apart, revealing temporal evolution of borehole microbiology. Meteoric groundwater feeding boreholes demonstrated variable recharge rates likely due to a complex and undefined fracture system within the host rock. 16S rRNA gene analysis determined that unique microbial communities occupy the four boreholes examined. Two boreholes yielded sequences revealing the presence of Desulfosporosinus, Candidatus Nitrotoga, and Chelatococcus associated with endemic subsurface communities. Two other boreholes presented sequences related to nonsubsurface-originating microbiota. High concentration of sulfate along with detected sulfur reducing and oxidizing microorganisms suggests that sulfur related metabolic strategies are prominent within these near-subsurface boreholes. Overall, results indicate that microbial community composition in the near-subsurface is highly dynamic at very fine spatial scales (<20 cm) within fluid-rock equilibrated boreholes, which additionally supports the role of a relationship for surface geochemical processes infiltrating and influencing subsurface environments. IMPORTANCE The Edgar Experimental Mine, Idaho Springs, CO, provides inexpensive and open access to borehole investigations for subsurface microbiology studies. Understanding how microbial processes in the near subsurface are connected to surface hydrological influences is lacking. Investigating microbial communities of subsurface mine boreholes provides evidence of how geochemical processes are linked to biogeochemical processes within each borehole and the geochemical connectedness and mobility of surface influences. This study details microbial community composition and fluid geochemistry over spatial and temporal scales from boreholes within the Edgar Mine. These findings are relevant to biogeochemistry of near-surface mines, caves, and other voids across planetary terrestrial systems. In addition, this work can lead to understanding how microbial communities relate to both fluid-rock equilibration, and geochemical influences may enhance our understanding of subsurface molecular biological tools that aid mining economic practices to reflect biological signals for lucrative veins in the near subsurface.
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Affiliation(s)
- Patrick H. Thieringer
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado, USA
| | - Alexander S. Honeyman
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado, USA
| | - John R. Spear
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado, USA
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28
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Decreasing extents of Archean serpentinization contributed to the rise of an oxidized atmosphere. Nat Commun 2021; 12:7341. [PMID: 34930924 PMCID: PMC8688491 DOI: 10.1038/s41467-021-27589-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 11/03/2021] [Indexed: 11/09/2022] Open
Abstract
At present, molecular hydrogen (H2) produced through Fe(II) oxidation during serpentinization of ultramafic rocks represents a small fraction of the global sink for O2 due to limited exposures of ultramafic rocks. In contrast, ultramafic rocks such as komatiites were much more common in the Early Earth and H2 production via serpentinization was a likely factor in maintaining an O2-free atmosphere throughout most of the Archean. Using thermodynamic simulations, this work quantifies the global O2 consumption attributed to serpentinization during the past 3.5 billion years. Results show that H2 generation is strongly dependent on rock compositions where serpentinization of more magnesian lithologies generated substantially higher amounts of H2. Consumption of >2 Tmole O2 yr-1 via low-temperature serpentinization of Archean continents and seafloor is possible. This O2 sink diminished greatly towards the end of the Archean as ultramafic rocks became less common and helped set the stage for the Great Oxidation Event.
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29
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Tarnas JD, Stack KM, Parente M, Koeppel AHD, Mustard JF, Moore KR, Horgan BHN, Seelos FP, Cloutis EA, Kelemen PB, Flannery D, Brown AJ, Frizzell KR, Pinet P. Characteristics, Origins, and Biosignature Preservation Potential of Carbonate-Bearing Rocks Within and Outside of Jezero Crater. JOURNAL OF GEOPHYSICAL RESEARCH. PLANETS 2021; 126:e2021JE006898. [PMID: 34824965 PMCID: PMC8597593 DOI: 10.1029/2021je006898] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 09/24/2021] [Accepted: 09/24/2021] [Indexed: 05/20/2023]
Abstract
Carbonate minerals have been detected in Jezero crater, an ancient lake basin that is the landing site of the Mars 2020 Perseverance rover, and within the regional olivine-bearing (ROB) unit in the Nili Fossae region surrounding this crater. It has been suggested that some carbonates in the margin fractured unit, a rock unit within Jezero crater, formed in a fluviolacustrine environment, which would be conducive to preservation of biosignatures from paleolake-inhabiting lifeforms. Here, we show that carbonate-bearing rocks within and outside of Jezero crater have the same range of visible-to-near-infrared carbonate absorption strengths, carbonate absorption band positions, thermal inertias, and morphologies. Thicknesses of exposed carbonate-bearing rock cross-sections in Jezero crater are ∼75-90 m thicker than typical ROB unit cross-sections in the Nili Fossae region, but have similar thicknesses to ROB unit exposures in Libya Montes. These similarities in carbonate properties within and outside of Jezero crater is consistent with a shared origin for all of the carbonates in the Nili Fossae region. Carbonate absorption minima positions indicate that both Mg- and more Fe-rich carbonates are present in the Nili Fossae region, consistent with the expected products of olivine carbonation. These estimated carbonate chemistries are similar to those in martian meteorites and the Comanche carbonates investigated by the Spirit rover in Columbia Hills. Our results indicate that hydrothermal alteration is the most likely formation mechanism for non-deltaic carbonates within and outside of Jezero crater.
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Affiliation(s)
- J. D. Tarnas
- NASA Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - K. M. Stack
- NASA Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - M. Parente
- Department of Electrical and Computer EngineeringUniversity of Massachusetts at AmherstAmherstMAUSA
| | - A. H. D. Koeppel
- Department of Astronomy and Planetary ScienceNorthern Arizona UniversityFlagstaffAZUSA
| | - J. F. Mustard
- Department of Earth, Environmental and Planetary SciencesBrown UniversityProvidenceRIUSA
| | - K. R. Moore
- NASA Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - B. H. N. Horgan
- Department of Earth, Atmospheric, and Planetary SciencesPurdue UniversityWest LafayetteINUSA
| | - F. P. Seelos
- Johns Hopkins University Applied Physics LabLaurelMDUSA
| | - E. A. Cloutis
- Department of GeographyUniversity of WinnipegWinnipegMBCanada
| | - P. B. Kelemen
- Lahmont‐Doherty Earth Observatory, Columbia UniversityPalisadesNYUSA
| | - D. Flannery
- School of Earth and Atmospheric SciencesQueensland University of TechnologyBrisbaneQLDAustralia
| | | | - K. R. Frizzell
- Department of Earth and Planetary SciencesRutgers UniversityPiscatawayNJUSA
| | - P. Pinet
- Institut de Recherche en Astrophysique et PlanétologieToulouseFrance
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30
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Leask EK, Ehlmann BL, Greenberger RN, Pinet P, Daydou Y, Ceuleneer G, Kelemen P. Tracing Carbonate Formation, Serpentinization, and Biological Materials With Micro-/Meso-Scale Infrared Imaging Spectroscopy in a Mars Analog System, Samail Ophiolite, Oman. EARTH AND SPACE SCIENCE (HOBOKEN, N.J.) 2021; 8:e2021EA001637. [PMID: 34820479 PMCID: PMC8596454 DOI: 10.1029/2021ea001637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2021] [Revised: 09/14/2021] [Accepted: 09/20/2021] [Indexed: 05/25/2023]
Abstract
Visible-shortwave infrared (VSWIR) imaging spectrometers map composition remotely with spatial context, typically at many meters-scale from orbital and airborne data. Here, we evaluate VSWIR imaging spectroscopy capabilities at centimeters to sub-millimeter scale at the Samail Ophiolite, Oman, where mafic and ultramafic lithologies and their alteration products, including serpentine and carbonates, are exposed in a semi-arid environment, analogous to similar mineral associations observed from Mars orbit that will be explored by the Mars-2020 rover. At outcrop and hand specimen scales, VSWIR spectroscopy (a) identifies cross-cutting veins of calcite, dolomite, magnesite, serpentine, and chlorite that record pathways and time-order of multiple alteration events of changing fluid composition; (b) detects small-scale, partially altered remnant pyroxenes and localized epidote and prehnite that indicate protolith composition and temperatures and pressures of multiple generations of faulting and alteration, respectively; and (c) discriminates between spectrally similar carbonate and serpentine phases and carbonate solid solutions. In natural magnesite veins, minor amounts of ferrous iron can appear similar to olivine's strong 1-μm absorption, though no olivine is present. We also find that mineral identification for carbonate and serpentine in mixtures with each other is strongly scale- and texture-dependent; ∼40 area% dolomite in mm-scale veins at one serpentinite outcrop and ∼18 area% serpentine in a calcite-rich travertine outcrop are not discriminated until spatial scales of <∼1-2 cm/pixel. We found biological materials, for example bacterial mats versus vascular plants, are differentiated using wavelengths <1 μm while shortwave infrared wavelengths >1 μm are required to identify most organic materials and distinguish most mineral phases.
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Affiliation(s)
- Ellen K. Leask
- Division of Geological & Planetary SciencesCalifornia Institute of TechnologyPasadenaCAUSA
- Now at Johns Hopkins University/Applied Physics LaboratoryLaurelMDUSA
| | - Bethany L. Ehlmann
- Division of Geological & Planetary SciencesCalifornia Institute of TechnologyPasadenaCAUSA
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - Rebecca N. Greenberger
- Division of Geological & Planetary SciencesCalifornia Institute of TechnologyPasadenaCAUSA
| | - Patrick Pinet
- Institut de Recherche en Astrophysique et Planétologie (IRAP)Université de ToulouseCNRSUPSCNESToulouseFrance
| | - Yves Daydou
- Institut de Recherche en Astrophysique et Planétologie (IRAP)Université de ToulouseCNRSUPSCNESToulouseFrance
| | - Georges Ceuleneer
- Geosciences Environnement Toulouse (GET)Université de ToulouseCNRSUPSToulouseFrance
| | - Peter Kelemen
- Department of Earth & Environmental SciencesColumbia UniversityLamont Doherty Earth ObservatoryPalisadesNYUSA
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Microbial Communities in a Serpentinizing Aquifer Are Assembled through Strong Concurrent Dispersal Limitation and Selection. mSystems 2021; 6:e0030021. [PMID: 34519519 PMCID: PMC8547479 DOI: 10.1128/msystems.00300-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
In recent years, our appreciation of the extent of habitable environments in Earth’s subsurface has greatly expanded, as has our understanding of the biodiversity contained within. Most studies have relied on single sampling points, rather than considering the long-term dynamics of subsurface environments and their microbial populations. One such habitat are aquifers associated with the aqueous alteration of ultramafic rocks through a process known as serpentinization. Ecological modeling performed on a multiyear time series of microbiology, hydrology, and geochemistry in an ultrabasic aquifer within the Coast Range Ophiolite reveals that community assembly is governed by undominated assembly (i.e., neither stochastic [random] nor deterministic [selective] processes alone govern assembly). Controls on community assembly were further assessed by characterizing aquifer hydrogeology and microbial community adaptations to the environment. These analyses show that low permeability rocks in the aquifer restrict the transmission of microbial populations between closely situated wells. Alpha and beta diversity measures and metagenomic and metatranscriptomic data from microbial communities indicate that high pH and low dissolved inorganic carbon levels impose strong environmental selection on microbial communities within individual wells. Here, we find that the interaction between strong selection imposed by extreme pH and enhanced ecological drift due to dispersal limitation imposed by slow fluid flow results in the undominated assembly signal observed throughout the site. Strong environmental selection paired with extremely low dispersal in the subsurface results in low diversity microbial communities that are well adapted to extreme pH conditions and subject to enhanced stochasticity introduced by ecological drift over time. IMPORTANCE Microbial communities existing under extreme or stressful conditions have long been thought to be structured primarily by deterministic processes. The application of macroecology theory and modeling to microbial communities in recent years has spurred assessment of assembly processes in microbial communities, revealing that both stochastic and deterministic processes are at play to different extents within natural environments. We show that low diversity microbial communities in a hard-rock serpentinizing aquifer are assembled under the influence of strong selective processes imposed by high pH and enhanced ecological drift that occurs as the result of dispersal limitation due to the slow movement of water in the low permeability aquifer. This study demonstrates the important roles that both selection and dispersal limitation play in terrestrial serpentinites, where extreme pH assembles a microbial metacommunity well adapted to alkaline conditions and dispersal limitation drives compositional differences in microbial community composition between local communities in the subsurface.
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Coskun ÖK, Vuillemin A, Schubotz F, Klein F, Sichel SE, Eisenreich W, Orsi WD. Quantifying the effects of hydrogen on carbon assimilation in a seafloor microbial community associated with ultramafic rocks. ISME JOURNAL 2021; 16:257-271. [PMID: 34312482 PMCID: PMC8692406 DOI: 10.1038/s41396-021-01066-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Revised: 07/05/2021] [Accepted: 07/09/2021] [Indexed: 11/09/2022]
Abstract
Thermodynamic models predict that H2 is energetically favorable for seafloor microbial life, but how H2 affects anabolic processes in seafloor-associated communities is poorly understood. Here, we used quantitative 13C DNA stable isotope probing (qSIP) to quantify the effect of H2 on carbon assimilation by microbial taxa synthesizing 13C-labeled DNA that are associated with partially serpentinized peridotite rocks from the equatorial Mid-Atlantic Ridge. The rock-hosted seafloor community was an order of magnitude more diverse compared to the seawater community directly above the rocks. With added H2, peridotite-associated taxa increased assimilation of 13C-bicarbonate and 13C-acetate into 16S rRNA genes of operational taxonomic units by 146% (±29%) and 55% (±34%), respectively, which correlated with enrichment of H2-oxidizing NiFe-hydrogenases encoded in peridotite-associated metagenomes. The effect of H2 on anabolism was phylogenetically organized, with taxa affiliated with Atribacteria, Nitrospira, and Thaumarchaeota exhibiting the most significant increases in 13C-substrate assimilation in the presence of H2. In SIP incubations with added H2, an order of magnitude higher number of peridotite rock-associated taxa assimilated 13C-bicarbonate, 13C-acetate, and 13C-formate compared to taxa that were not associated with peridotites. Collectively, these findings indicate that the unique geochemical nature of the peridotite-hosted ecosystem has selected for H2-metabolizing, rock-associated taxa that can increase anabolism under high H2 concentrations. Because ultramafic rocks are widespread in slow-, and ultraslow-spreading oceanic lithosphere, continental margins, and subduction zones where H2 is formed in copious amounts, the link between H2 and carbon assimilation demonstrated here may be widespread within these geological settings.
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Affiliation(s)
- Ömer K Coskun
- Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität, Munich, Germany
| | - Aurèle Vuillemin
- Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität, Munich, Germany.,GFZ German Research Centre for Geosciences, Helmholtz Centre Potsdam, Potsdam, Germany
| | - Florence Schubotz
- MARUM Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
| | - Frieder Klein
- Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Susanna E Sichel
- Departamento de Geologia e Geofísica/LAGEMAR-Universidade Federal Fluminense-Brazil, Niterói, RJ, Brazil
| | - Wolfgang Eisenreich
- Department of Chemistry, Bavarian NMR Center-Structural Membrane Biochemistry, Technische Universität München, Garching, Germany
| | - William D Orsi
- Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität, Munich, Germany. .,GeoBio-CenterLMU, Ludwig-Maximilians-Universität München, Munich, Germany.
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Cockell CS, Schaefer B, Wuchter C, Coolen MJL, Grice K, Schnieders L, Morgan JV, Gulick SPS, Wittmann A, Lofi J, Christeson GL, Kring DA, Whalen MT, Bralower TJ, Osinski GR, Claeys P, Kaskes P, de Graaff SJ, Déhais T, Goderis S, Hernandez Becerra N, Nixon S. Shaping of the Present-Day Deep Biosphere at Chicxulub by the Impact Catastrophe That Ended the Cretaceous. Front Microbiol 2021; 12:668240. [PMID: 34248877 PMCID: PMC8264514 DOI: 10.3389/fmicb.2021.668240] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 05/10/2021] [Indexed: 01/04/2023] Open
Abstract
We report on the effect of the end-Cretaceous impact event on the present-day deep microbial biosphere at the impact site. IODP-ICDP Expedition 364 drilled into the peak ring of the Chicxulub crater, México, allowing us to investigate the microbial communities within this structure. Increased cell biomass was found in the impact suevite, which was deposited within the first few hours of the Cenozoic, demonstrating that the impact produced a new lithological horizon that caused a long-term improvement in deep subsurface colonization potential. In the biologically impoverished granitic rocks, we observed increased cell abundances at impact-induced geological interfaces, that can be attributed to the nutritionally diverse substrates and/or elevated fluid flow. 16S rRNA gene amplicon sequencing revealed taxonomically distinct microbial communities in each crater lithology. These observations show that the impact caused geological deformation that continues to shape the deep subsurface biosphere at Chicxulub in the present day.
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Affiliation(s)
- Charles S Cockell
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
| | - Bettina Schaefer
- WA-Organic and Isotope Geochemistry Centre (WA-OIGC), School of Earth and Planetary Sciences, The Institute for Geoscience Research, Curtin University, Bentley, WA, Australia
| | - Cornelia Wuchter
- WA-Organic and Isotope Geochemistry Centre (WA-OIGC), School of Earth and Planetary Sciences, The Institute for Geoscience Research, Curtin University, Bentley, WA, Australia
| | - Marco J L Coolen
- WA-Organic and Isotope Geochemistry Centre (WA-OIGC), School of Earth and Planetary Sciences, The Institute for Geoscience Research, Curtin University, Bentley, WA, Australia
| | - Kliti Grice
- WA-Organic and Isotope Geochemistry Centre (WA-OIGC), School of Earth and Planetary Sciences, The Institute for Geoscience Research, Curtin University, Bentley, WA, Australia
| | - Luzie Schnieders
- MARUM-Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
| | - Joanna V Morgan
- Department of Earth Science and Engineering, Imperial College London, London, United Kingdom
| | - Sean P S Gulick
- Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, Austin, TX, United States.,Department of Geological Sciences, Jackson School of Geosciences, University of Texas at Austin, Austin, TX, United States.,Center for Planetary Systems Habitability, University of Texas at Austin, Austin, TX, United States
| | - Axel Wittmann
- Arizona State University, Eyring Materials Center, Tempe, AZ, United States
| | - Johanna Lofi
- Géosciences Montpellier, Université de Montpellier, CNRS, Montpellier, France
| | - Gail L Christeson
- Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, Austin, TX, United States
| | - David A Kring
- Lunar and Planetary Institute, Houston, TX, United States
| | - Michael T Whalen
- Department of Geosciences, University of Alaska Fairbanks, Fairbanks, AK, United States
| | - Timothy J Bralower
- Department of Geosciences, Pennsylvania State University, University Park, PA, United States
| | - Gordon R Osinski
- Institute for Earth and Space Exploration and Department of Earth Sciences, University of Western Ontario, London, ON, Canada
| | - Philippe Claeys
- Analytical, Environmental and Geo-Chemistry, Vrije Universiteit Brussel, Brussels, Belgium
| | - Pim Kaskes
- Analytical, Environmental and Geo-Chemistry, Vrije Universiteit Brussel, Brussels, Belgium
| | - Sietze J de Graaff
- Analytical, Environmental and Geo-Chemistry, Vrije Universiteit Brussel, Brussels, Belgium
| | - Thomas Déhais
- Analytical, Environmental and Geo-Chemistry, Vrije Universiteit Brussel, Brussels, Belgium
| | - Steven Goderis
- Analytical, Environmental and Geo-Chemistry, Vrije Universiteit Brussel, Brussels, Belgium
| | - Natali Hernandez Becerra
- Department of Earth and Environmental Sciences, University of Manchester, Manchester, IN, United States
| | - Sophie Nixon
- Department of Earth and Environmental Sciences, University of Manchester, Manchester, IN, United States
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Procaryotic Diversity and Hydrogenotrophic Methanogenesis in an Alkaline Spring (La Crouen, New Caledonia). Microorganisms 2021; 9:microorganisms9071360. [PMID: 34201651 PMCID: PMC8307142 DOI: 10.3390/microorganisms9071360] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 06/17/2021] [Accepted: 06/19/2021] [Indexed: 01/01/2023] Open
Abstract
(1) Background: The geothermal spring of La Crouen (New Caledonia) discharges warm (42 °C) alkaline water (pH~9) enriched in dissolved nitrogen with traces of methane, but its microbial diversity has not yet been studied. (2) Methods: Cultivation-dependent and -independent methods (e.g., Illumina sequencing and quantitative PCR based on 16S rRNA gene) were used to describe the prokaryotic diversity of this spring. (3) Results: Prokaryotes were mainly represented by Proteobacteria (57% on average), followed by Cyanobacteria, Chlorofexi, and Candidatus Gracilibacteria (GN02/BD1-5) (each > 5%). Both potential aerobes and anaerobes, as well as mesophilic and thermophilic microorganisms, were identified. Some of them had previously been detected in continental hyperalkaline springs found in serpentinizing environments (The Cedars, Samail, Voltri, and Zambales ophiolites). Gammaproteobacteria, Ca. Gracilibacteria and Thermotogae were significantly more abundant in spring water than in sediments. Potential chemolithotrophs mainly included beta- and gammaproteobacterial genera of sulfate-reducers (Ca. Desulfobacillus), methylotrophs (Methyloversatilis), sulfur-oxidizers (Thiofaba, Thiovirga), or hydrogen-oxidizers (Hydrogenophaga). Methanogens (Methanobacteriales and Methanosarcinales) were the dominant Archaea, as found in serpentinization-driven and deep subsurface ecosystems. A novel alkaliphilic hydrogenotrophic methanogen (strain CAN) belonging to the genus Methanobacterium was isolated, suggesting that hydrogenotrophic methanogenesis occurs at La Crouen.
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Sanz JL, Rodriguez N, Escudero C, Carrizo D, Amils R. Biological production of H 2 , CH 4 and CO 2 in the deep subsurface of the Iberian Pyrite Belt. Environ Microbiol 2021; 23:3913-3922. [PMID: 33973338 DOI: 10.1111/1462-2920.15561] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 04/29/2021] [Accepted: 05/01/2021] [Indexed: 11/26/2022]
Abstract
Most of the terrestrial deep subsurfaces are oligotrophic environments in which some gases, mainly H2 , CH4 and CO2 , play an important role as energy and/or carbon sources. In this work, we assessed their biotic and abiotic origin in samples from subsurface hard-rock cores of the Iberian Pyrite Belt (IPB) at three different depths (414, 497 and 520 m). One set of samples was sterilized (abiotic control) and all samples were incubated under anaerobic conditions. Our results showed that H2 , CH4 and CO2 remained low and constant in the sterilized controls while their levels were 4, 4.1 and 2.5 times higher respectively, in the unsterilized samples compared to the abiotic controls. The δ13 CCH4 -values measured in the samples (range -31.2 to -43.0 ‰) reveals carbon isotopic signatures that are within the range for biological methane production. Possible microorganisms responsible for the biotic production of the gases were assessed by CARD-FISH. The analysis of sequenced genomes of detected microorganisms within the subsurface of the IPB allowed to identify possible metabolic activities involved in H2 (Rhodoplanes, Shewanella and Desulfosporosinus), CH4 (Methanobacteriales) and CO2 production. The obtained results suggest that part of the H2 , CH4 and CO2 detected in the deep subsurface has a biological origin.
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Affiliation(s)
- Jose L Sanz
- Molecular Biology Department, Universidad Autónoma de Madrid, Madrid, Spain
| | - Nuria Rodriguez
- Centro de Astrobiología (INTA-CSIC), Torrejón de Ardoz, 28850, Spain
| | - Cristina Escudero
- Centro de Astrobiología (INTA-CSIC), Torrejón de Ardoz, 28850, Spain.,Centro de Biología Molecular Severo Ochoa (UAM-CSIC), Universidad Autónoma de Madrid, Madrid, 28049, Spain
| | - Daniel Carrizo
- Centro de Astrobiología (INTA-CSIC), Torrejón de Ardoz, 28850, Spain
| | - Ricardo Amils
- Centro de Astrobiología (INTA-CSIC), Torrejón de Ardoz, 28850, Spain.,Centro de Biología Molecular Severo Ochoa (UAM-CSIC), Universidad Autónoma de Madrid, Madrid, 28049, Spain
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Quéméneur M, Erauso G, Bartoli M, Vandecasteele C, Wils L, Gil L, Monnin C, Pelletier B, Postec A. Alkalicella caledoniensis gen. nov., sp. nov., a novel alkaliphilic anaerobic bacterium isolated from 'La Crouen' alkaline thermal spring, New Caledonia. Int J Syst Evol Microbiol 2021; 71. [PMID: 34003738 DOI: 10.1099/ijsem.0.004810] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A novel anaerobic, alkaliphilic, mesophilic, Gram-stain-positive, endospore-forming bacterium was isolated from an alkaline thermal spring (42 °C, pH 9.0) in New Caledonia. This bacterium, designated strain LB2T, grew at 25-50 °C (optimum, 37 °C) and pH 8.2-10.8 (optimum, pH 9.5). Added NaCl was not required for growth (optimum, 0-1 %) but was tolerated up to 7 %. Strain LB2T utilized a limited range of substrates, such as peptone, pyruvate, yeast extract and xylose. End products detected from pyruvate fermentation were acetate and formate. Both ferric citrate and thiosulfate were used as electron acceptors. Elemental sulphur, nitrate, nitrite, fumarate, sulphate, sulfite and DMSO were not used as terminal electron acceptors. The two major cellular fatty acids were iso-C15 : 0 and C16 : 0. The genome consists of a circular chromosome (3.7 Mb) containing 3626 predicted protein-encoding genes with a G+C content of 36.2 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that the isolate is a member of the family Proteinivoraceae, order Clostridiales within the phylum Firmicutes. Strain LB2T was most closely related to the thermophilic Anaerobranca gottschalkii LBS3T (93.2 % 16S rRNA gene sequence identity). Genome-based analysis of average nucleotide identity and digital DNA-DNA hybridization of strain LB2T with A. gottschalkii LBS3T showed respective values of 70.8 and 13.4 %. Based on phylogenetic, genomic, chemotaxonomic and physiological properties, strain LB2T is proposed to represent the first species of a novel genus, for which the name Alkalicella caledoniensis gen. nov., sp. nov. is proposed (type strain LB2T=DSM 100588T=JCM 30958T).
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Affiliation(s)
- Marianne Quéméneur
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO, Marseille, France
| | - Gaël Erauso
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO, Marseille, France
| | - Manon Bartoli
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO, Marseille, France
| | | | - Laura Wils
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO, Marseille, France
| | - Lisa Gil
- INRAe, US 1426, GeT-PlaGe, Genotoul, Castanet-Tolosan, France
| | - Christophe Monnin
- GET UMR5563 (CNRS/UPS/IRD/CNES), Géosciences Environnement Toulouse, 14 Avenue Edouard Belin, 31400 Toulouse, France
| | - Bernard Pelletier
- Centre IRD de Nouméa, 101 Promenade Roger Laroque, BP A5 - 98848 Nouméa cedex, Nouvelle-Calédonie
| | - Anne Postec
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO, Marseille, France
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Fones EM, Colman DR, Kraus EA, Stepanauskas R, Templeton AS, Spear JR, Boyd ES. Diversification of methanogens into hyperalkaline serpentinizing environments through adaptations to minimize oxidant limitation. THE ISME JOURNAL 2021; 15:1121-1135. [PMID: 33257813 PMCID: PMC8115248 DOI: 10.1038/s41396-020-00838-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 10/28/2020] [Accepted: 11/11/2020] [Indexed: 01/29/2023]
Abstract
Metagenome assembled genomes (MAGs) and single amplified genomes (SAGs) affiliated with two distinct Methanobacterium lineages were recovered from subsurface fracture waters of the Samail Ophiolite, Sultanate of Oman. Lineage Type I was abundant in waters with circumneutral pH, whereas lineage Type II was abundant in hydrogen rich, hyperalkaline waters. Type I encoded proteins to couple hydrogen oxidation to CO2 reduction, typical of hydrogenotrophic methanogens. Surprisingly, Type II, which branched from the Type I lineage, lacked homologs of two key oxidative [NiFe]-hydrogenases. These functions were presumably replaced by formate dehydrogenases that oxidize formate to yield reductant and cytoplasmic CO2 via a pathway that was unique among characterized Methanobacteria, allowing cells to overcome CO2/oxidant limitation in high pH waters. This prediction was supported by microcosm-based radiotracer experiments that showed significant biological methane generation from formate, but not bicarbonate, in waters where the Type II lineage was detected in highest relative abundance. Phylogenetic analyses and variability in gene content suggested that recent and ongoing diversification of the Type II lineage was enabled by gene transfer, loss, and transposition. These data indicate that selection imposed by CO2/oxidant availability drove recent methanogen diversification into hyperalkaline waters that are heavily impacted by serpentinization.
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Affiliation(s)
- Elizabeth M. Fones
- grid.41891.350000 0001 2156 6108Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717 USA
| | - Daniel R. Colman
- grid.41891.350000 0001 2156 6108Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717 USA
| | - Emily A. Kraus
- grid.254549.b0000 0004 1936 8155Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO 80401 USA
| | - Ramunas Stepanauskas
- grid.296275.d0000 0000 9516 4913Bigelow Laboratory for Ocean Sciences, East Boothbay, ME 04544 USA
| | - Alexis S. Templeton
- grid.266190.a0000000096214564Department of Geological Sciences, University of Colorado, Boulder, CO 80309 USA
| | - John R. Spear
- grid.254549.b0000 0004 1936 8155Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO 80401 USA
| | - Eric S. Boyd
- grid.41891.350000 0001 2156 6108Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717 USA
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Sheik CS, Badalamenti JP, Telling J, Hsu D, Alexander SC, Bond DR, Gralnick JA, Lollar BS, Toner BM. Novel Microbial Groups Drive Productivity in an Archean Iron Formation. Front Microbiol 2021; 12:627595. [PMID: 33859627 PMCID: PMC8042283 DOI: 10.3389/fmicb.2021.627595] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 03/01/2021] [Indexed: 12/23/2022] Open
Abstract
Deep subsurface environments are decoupled from Earth's surface processes yet diverse, active, and abundant microbial communities thrive in these isolated environments. Microbes inhabiting the deep biosphere face unique challenges such as electron donor/acceptor limitations, pore space/fracture network limitations, and isolation from other microbes within the formation. Of the few systems that have been characterized, it is apparent that nutrient limitations likely facilitate diverse microbe-microbe interactions (i.e., syntrophic, symbiotic, or parasitic) and that these interactions drive biogeochemical cycling of major elements. Here we describe microbial communities living in low temperature, chemically reduced brines at the Soudan Underground Mine State Park, United States. The Soudan Iron mine intersects a massive hematite formation at the southern extent of the Canadian Shield. Fractured rock aquifer brines continuously flow from exploratory boreholes drilled circa 1960 and are enriched in deuterium compared to the global meteoric values, indicating brines have had little contact with surface derived waters, and continually degas low molecular weight hydrocarbons C1-C4. Microbial enrichments suggest that once brines exit the boreholes, oxidation of the hydrocarbons occur. Amplicon sequencing show these borehole communities are low in diversity and dominated by Firmicute and Proteobacteria phyla. From the metagenome assemblies, we recovered approximately thirty genomes with estimated completion over 50%. Analysis of genome taxonomy generally followed the amplicon data, and highlights that several of the genomes represent novel families and genera. Metabolic reconstruction shows two carbon-fixation pathways were dominant, the Wood-Ljungdahl (acetogenesis) and Calvin-Benson-Bassham (via RuBisCo), indicating that inorganic carbon likely enters into the microbial foodweb with differing carbon fractionation potentials. Interestingly, methanogenesis is likely driven by Methanolobus and suggests cycling of methylated compounds and not H2/CO2 or acetate. Furthermore, the abundance of sulfate in brines suggests cryptic sulfur cycling may occur, as we detect possible sulfate reducing and thiosulfate oxidizing microorganisms. Finally, a majority of the microorganisms identified contain genes that would allow them to participate in several element cycles, highlighting that in these deep isolated systems metabolic flexibility may be an important life history trait.
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Affiliation(s)
- Cody S. Sheik
- Department of Biology and the Large Lakes Observatory, University of Minnesota Duluth, Duluth, MN, United States
| | - Jonathan P. Badalamenti
- University of Minnesota Genomics Center, University of Minnesota Twin Cities, Minneapolis, MN, United States
- Biotechnology Institute, University of Minnesota Twin Cities, Saint Paul, MN, United States
| | - Jon Telling
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - David Hsu
- Biotechnology Institute, University of Minnesota Twin Cities, Saint Paul, MN, United States
- Plant and Microbial Biology, University of Minnesota Twin Cities, Saint Paul, MN, United States
| | - Scott C. Alexander
- Department of Earth and Environmental Sciences, University of Minnesota Twin Cities, Minneapolis, MN, United States
| | - Daniel R. Bond
- Biotechnology Institute, University of Minnesota Twin Cities, Saint Paul, MN, United States
- Plant and Microbial Biology, University of Minnesota Twin Cities, Saint Paul, MN, United States
| | - Jeffrey A. Gralnick
- Biotechnology Institute, University of Minnesota Twin Cities, Saint Paul, MN, United States
- Plant and Microbial Biology, University of Minnesota Twin Cities, Saint Paul, MN, United States
| | | | - Brandy M. Toner
- Department of Earth and Environmental Sciences, University of Minnesota Twin Cities, Minneapolis, MN, United States
- Department of Soil, Water, and Climate, University of Minnesota Twin Cities, Saint Paul, MN, United States
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Veneranda M, Lopez-Reyes G, Pascual Sanchez E, Krzesińska AM, Manrique-Martinez JA, Sanz-Arranz A, Lantz C, Lalla E, Moral A, Medina J, Poulet F, Dypvik H, Werner SC, Vago JL, Rull F. ExoMars Raman Laser Spectrometer: A Tool to Semiquantify the Serpentinization Degree of Olivine-Rich Rocks on Mars. ASTROBIOLOGY 2021; 21:307-322. [PMID: 33252242 DOI: 10.1089/ast.2020.2265] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We evaluated the effectiveness of the ExoMars Raman laser spectrometer (RLS) to determine the degree of serpentinization of olivine-rich units on Mars. We selected terrestrial analogs of martian ultramafic rocks from the Leka Ophiolite Complex (LOC) and analyzed them with both laboratory and flight-like analytical instruments. We first studied the mineralogical composition of the samples (mostly olivine and serpentine) with state-of-the-art diffractometric (X-ray diffractometry [XRD]) and spectroscopic (Raman, near-infrared spectroscopy [NIR]) laboratory systems. We compared these results with those obtained using our RLS ExoMars Simulator. Our work shows that the RLS ExoMars Simulator successfully identified all major phases. Moreover, when emulating the automatic operating mode of the flight instrument, the RLS ExoMars Simulator also detected several minor compounds (pyroxene and brucite), some of which were not observed by NIR and XRD (e.g., calcite). Thereafter, we produced RLS-dedicated calibration curves (R2 between 0.9993 and 0.9995 with an uncertainty between ±3.0% and ±5.2% with a confidence interval of 95%) to estimate the relative content of olivine and serpentine in the samples. Our results show that RLS can be very effective in identifying serpentine, a scientific target of primary importance for the potential detection of biosignatures on Mars-the main objective of the ExoMars rover mission.
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Affiliation(s)
- Marco Veneranda
- Department of Condensed Matter Physics, Crystallography and Mineralogy, University of Valladolid, Valladolid, Spain
| | - Guillermo Lopez-Reyes
- Department of Condensed Matter Physics, Crystallography and Mineralogy, University of Valladolid, Valladolid, Spain
| | - Elena Pascual Sanchez
- Department of Condensed Matter Physics, Crystallography and Mineralogy, University of Valladolid, Valladolid, Spain
| | - Agata M Krzesińska
- Department of Geosciences, Centre for Earth Evolution and Dynamics, University of Oslo, Oslo, Norway
| | | | - Aurelio Sanz-Arranz
- Department of Condensed Matter Physics, Crystallography and Mineralogy, University of Valladolid, Valladolid, Spain
| | - Cateline Lantz
- Institut d'Astrophysique Spatiale, CNRS/Université Paris-Sud, Orsay, France
| | - Emmanuel Lalla
- Department of Earth and Space Science and Engineering, York University, Toronto, Canada
| | - Andoni Moral
- Department of Space Programs, Instituto Nacional de Técnica Aeroespacial (INTA), Madrid, Spain
| | - Jesús Medina
- Department of Condensed Matter Physics, Crystallography and Mineralogy, University of Valladolid, Valladolid, Spain
| | - Francois Poulet
- Institut d'Astrophysique Spatiale, CNRS/Université Paris-Sud, Orsay, France
| | - Henning Dypvik
- Department of Geosciences, Centre for Earth Evolution and Dynamics, University of Oslo, Oslo, Norway
| | - Stephanie C Werner
- Department of Geosciences, Centre for Earth Evolution and Dynamics, University of Oslo, Oslo, Norway
| | | | - Fernando Rull
- Department of Condensed Matter Physics, Crystallography and Mineralogy, University of Valladolid, Valladolid, Spain
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Molecular Evidence for an Active Microbial Methane Cycle in Subsurface Serpentinite-Hosted Groundwaters in the Samail Ophiolite, Oman. Appl Environ Microbiol 2021; 87:AEM.02068-20. [PMID: 33127818 DOI: 10.1128/aem.02068-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 10/20/2020] [Indexed: 01/04/2023] Open
Abstract
Serpentinization can generate highly reduced fluids replete with hydrogen (H2) and methane (CH4), potent reductants capable of driving microbial methanogenesis and methanotrophy, respectively. However, CH4 in serpentinized waters is thought to be primarily abiogenic, raising key questions about the relative importance of methanogens and methanotrophs in the production and consumption of CH4 in these systems. Herein, we apply molecular approaches to examine the functional capability and activity of microbial CH4 cycling in serpentinization-impacted subsurface waters intersecting multiple rock and water types within the Samail Ophiolite of Oman. Abundant 16S rRNA genes and transcripts affiliated with the methanogenic genus Methanobacterium were recovered from the most alkaline (pH, >10), H2- and CH4-rich subsurface waters. Additionally, 16S rRNA genes and transcripts associated with the aerobic methanotrophic genus Methylococcus were detected in wells that spanned varied fluid geochemistry. Metagenomic sequencing yielded genes encoding homologs of proteins involved in the hydrogenotrophic pathway of microbial CH4 production and in microbial CH4 oxidation. Transcripts of several key genes encoding methanogenesis/methanotrophy enzymes were identified, predominantly in communities from the most hyperalkaline waters. These results indicate active methanogenic and methanotrophic populations in waters with hyperalkaline pH in the Samail Ophiolite, thereby supporting a role for biological CH4 cycling in aquifers that undergo low-temperature serpentinization.IMPORTANCE Serpentinization of ultramafic rock can generate conditions favorable for microbial methane (CH4) cycling, including the abiotic production of hydrogen (H2) and possibly CH4 Systems of low-temperature serpentinization are geobiological targets due to their potential to harbor microbial life and ubiquity throughout Earth's history. Biomass in fracture waters collected from the Samail Ophiolite of Oman, a system undergoing modern serpentinization, yielded DNA and RNA signatures indicative of active microbial methanogenesis and methanotrophy. Intriguingly, transcripts for proteins involved in methanogenesis were most abundant in the most highly reacted waters that have hyperalkaline pH and elevated concentrations of H2 and CH4 These findings suggest active biological methane cycling in serpentinite-hosted aquifers, even under extreme conditions of high pH and carbon limitation. These observations underscore the potential for microbial activity to influence the isotopic composition of CH4 in these systems, which is information that could help in identifying biosignatures of microbial activity on other planets.
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Escudero C, Del Campo A, Ares JR, Sánchez C, Martínez JM, Gómez F, Amils R. Visualizing Microorganism-Mineral Interaction in the Iberian Pyrite Belt Subsurface: The Acidovorax Case. Front Microbiol 2020; 11:572104. [PMID: 33324359 PMCID: PMC7726209 DOI: 10.3389/fmicb.2020.572104] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 10/20/2020] [Indexed: 11/18/2022] Open
Abstract
Despite being considered an extreme environment, several studies have shown that life in the deep subsurface is abundant and diverse. Microorganisms inhabiting these systems live within the rock pores and, therefore, the geochemical and geohydrological characteristics of this matrix may influence the distribution of underground biodiversity. In this study, correlative fluorescence and Raman microscopy (Raman-FISH) was used to analyze the mineralogy associated with the presence of members of the genus Acidovorax, an iron oxidizing microorganisms, in native rock samples of the Iberian Pyrite Belt subsurface. Our results suggest a strong correlation between the presence of Acidovorax genus and pyrite, suggesting that the mineral might greatly influence its subsurface distribution.
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Affiliation(s)
- Cristina Escudero
- Centro de Biología Molecular Severo Ochoa (CBMSO, CSIC-UAM), Universidad Autónoma de Madrid, Madrid, Spain.,Departamento de Planetología y Habitabilidad, Centro de Astrobiología (CAB, INTA-CSIC), Madrid, Spain
| | - Adolfo Del Campo
- Departamento de Electrocerámica, Instituto de Cerámica y Vidrio, CSIC, Madrid, Spain
| | - Jose R Ares
- Departamento de Física de Materiales, Universidad Autónoma de Madrid, Cantoblanco, Madrid, Spain
| | - Carlos Sánchez
- Departamento de Física de Materiales, Universidad Autónoma de Madrid, Cantoblanco, Madrid, Spain
| | - Jose M Martínez
- Centro de Biología Molecular Severo Ochoa (CBMSO, CSIC-UAM), Universidad Autónoma de Madrid, Madrid, Spain
| | - Felipe Gómez
- Departamento de Planetología y Habitabilidad, Centro de Astrobiología (CAB, INTA-CSIC), Madrid, Spain
| | - Ricardo Amils
- Centro de Biología Molecular Severo Ochoa (CBMSO, CSIC-UAM), Universidad Autónoma de Madrid, Madrid, Spain.,Departamento de Planetología y Habitabilidad, Centro de Astrobiología (CAB, INTA-CSIC), Madrid, Spain
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42
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Lecoeuvre A, Ménez B, Cannat M, Chavagnac V, Gérard E. Microbial ecology of the newly discovered serpentinite-hosted Old City hydrothermal field (southwest Indian ridge). ISME JOURNAL 2020; 15:818-832. [PMID: 33139872 PMCID: PMC8027613 DOI: 10.1038/s41396-020-00816-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 10/13/2020] [Accepted: 10/19/2020] [Indexed: 01/06/2023]
Abstract
Lost City (mid-Atlantic ridge) is a unique oceanic hydrothermal field where carbonate-brucite chimneys are colonized by a single phylotype of archaeal Methanosarcinales, as well as sulfur- and methane-metabolizing bacteria. So far, only one submarine analog of Lost City has been characterized, the Prony Bay hydrothermal field (New Caledonia), which nonetheless shows more microbiological similarities with ecosystems associated with continental ophiolites. This study presents the microbial ecology of the ‘Lost City’-type Old City hydrothermal field, recently discovered along the southwest Indian ridge. Five carbonate-brucite chimneys were sampled and subjected to mineralogical and geochemical analyses, microimaging, as well as 16S rRNA-encoding gene and metagenomic sequencing. Dominant taxa and metabolisms vary between chimneys, in conjunction with the predicted redox state, while potential formate- and CO-metabolizing microorganisms as well as sulfur-metabolizing bacteria are always abundant. We hypothesize that the variable environmental conditions resulting from the slow and diffuse hydrothermal fluid discharge that currently characterizes Old City could lead to different microbial populations between chimneys that utilize CO and formate differently as carbon or electron sources. Old City discovery and this first description of its microbial ecology opens up attractive perspectives for understanding environmental factors shaping communities and metabolisms in oceanic serpentinite-hosted ecosystems.
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Affiliation(s)
- Aurélien Lecoeuvre
- Université de Paris, Institut de physique du globe de Paris, CNRS UMR 7154, Paris, France.
| | - Bénédicte Ménez
- Université de Paris, Institut de physique du globe de Paris, CNRS UMR 7154, Paris, France
| | - Mathilde Cannat
- Université de Paris, Institut de physique du globe de Paris, CNRS UMR 7154, Paris, France
| | - Valérie Chavagnac
- Université de Toulouse, Géosciences Environnement Toulouse, CNRS UMR 5563, Toulouse, France
| | - Emmanuelle Gérard
- Université de Paris, Institut de physique du globe de Paris, CNRS UMR 7154, Paris, France
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43
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Martin WF. Carbon-Metal Bonds: Rare and Primordial in Metabolism. Trends Biochem Sci 2020; 44:807-818. [PMID: 31104860 DOI: 10.1016/j.tibs.2019.04.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 04/16/2019] [Accepted: 04/18/2019] [Indexed: 12/13/2022]
Abstract
Submarine hydrothermal vents are rich in hydrogen (H2), an ancient source of electrons and chemical energy for life. Geochemical H2 stems from serpentinization, a process in which rock-bound iron reduces water to H2. Reactions involving H2 and carbon dioxide (CO2) in hydrothermal systems generate abiotic methane and formate; these reactions resemble the core energy metabolism of methanogens and acetogens. These organisms are strict anaerobic autotrophs that inhabit hydrothermal vents and harness energy via H2-dependent CO2 reduction. Serpentinization also generates native metals, which can reduce CO2 to formate and acetate in the laboratory. The enzymes that channel H2, CO2, and dinitrogen (N2) into methanogen and acetogen metabolism are the backbone of the most ancient metabolic pathways. Their active sites share carbon-metal bonds which, although rare in biology, are conserved relics of primordial biochemistry present at the origin of life.
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Affiliation(s)
- William F Martin
- Institute for Molecular Evolution, University of Düsseldorf, 40225 Düsseldorf, Germany.
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44
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Newman SA, Lincoln SA, O'Reilly S, Liu X, Shock EL, Kelemen PB, Summons RE. Lipid Biomarker Record of the Serpentinite-Hosted Ecosystem of the Samail Ophiolite, Oman and Implications for the Search for Biosignatures on Mars. ASTROBIOLOGY 2020; 20:830-845. [PMID: 32648829 DOI: 10.1089/ast.2019.2066] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Serpentinization is a weathering process in which ultramafic rocks react with water, generating a range of products, including serpentine and other minerals, in addition to H2 and low-molecular-weight hydrocarbons that are capable of sustaining microbial life. Lipid biomarker analyses of serpentinite-hosted ecosystems hold promise as tools for investigating microbial activity in ancient Earth environments and other terrestrial planets such as Mars because lipids have the potential for longer term preservation relative to DNA, proteins, and other more labile organic molecules. Here, we report the first lipid biomarker record of microbial activity in the mantle section of the Samail Ophiolite, in the Sultanate of Oman, a site undergoing active serpentinization. We detected isoprenoidal (archaeal) and branched (bacterial) glycerol dialkyl glycerol tetraether (GDGT) lipids, including those with 0-3 cyclopentane moieties, and crenarchaeol, an isoprenoidal GDGT containing four cyclopentane and one cyclohexane moieties, as well as monoether lipids and fatty acids indicative of sulfate-reducing bacteria. Comparison of our geochemical data and 16S rRNA data from the Samail Ophiolite with those from other serpentinite-hosted sites identifies the existence of a common core serpentinization microbiome. In light of these findings, we also discuss the preservation potential of serpentinite lipid biomarker assemblages on Earth and Mars. Continuing investigations of the Samail Ophiolite and other terrestrial analogues will enhance our understanding of microbial habitability and diversity in serpentinite-hosted environments on Earth and elsewhere in the Solar System.
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Affiliation(s)
- Sharon A Newman
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California
| | - Sara A Lincoln
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts
- Department of Geosciences, The Pennsylvania State University, University Park, Pennsylvania
| | - Shane O'Reilly
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts
- School of Earth Sciences, University College Dublin, Belfield, Ireland
| | - Xiaolei Liu
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts
- School of Geology and Geophysics, University of Oklahoma, Norman, Oklahoma
| | - Everett L Shock
- School of Earth and Space Exploration, Arizona State University, Tempe, Arizona
- School of Molecular Sciences, Arizona State University, Tempe, Arizona
- Center for Fundamental and Applied Microbiomics, Arizona State University, Tempe, Arizona
| | - Peter B Kelemen
- Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York
| | - Roger E Summons
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts
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45
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Shi LD, Lv PL, Niu ZF, Lai CY, Zhao HP. Why does sulfate inhibit selenate reduction: Molybdenum deprivation from Mo-dependent selenate reductase. WATER RESEARCH 2020; 178:115832. [PMID: 32335368 DOI: 10.1016/j.watres.2020.115832] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 04/07/2020] [Accepted: 04/13/2020] [Indexed: 06/11/2023]
Abstract
Selenium pollution has become an increasingly serious global concern. Methane-fed selenate reduction has proven to be of great interest for the bioremediation of selenate-contaminated waters even with the coexistence of nitrate and dissolved oxygen. However, it is unclear if the common concurrent sulfate anion affects selenate removal. To address this question, we first introduced selenate (SeO42-) as the sole influent electron acceptor in a CH4-fed membrane biofilm reactor (CH4-MBfR); then we added different concentrations of sulfate (SO42-). The initial selenate removal efficiency (∼90%) was decreased by 50% in the presence of 15.6 μM of sulfate and completely inhibited after loading with 171.9 μM of sulfate. 16S rRNA gene sequencing showed that the selenate-reducing bacteria decreased after the addition of sulfate. Metagenomic sequencing showed that the abundance of genes encoding molybdenum (Mo)-dependent selenate reductase reduced by >50% when exposed to high concentrations of sulfate. Furthermore, the decrease in the total genes encoding all Mo-oxidoreductases was much greater than that of the genes encoding molybdate transporters, suggesting that the inhibition of selenate reduction by sulfate was most likely via the direct competition with molybdate for the transport system, leading to a lack of available Mo for Mo-dependent selenate reductases and thus reducing their activities. This result was confirmed by a batch test wherein the supplementation of molybdate mitigated the sulfate effect. Overall, this study shed light on the underlying mechanism of sulfate inhibition on selenate reduction and laid the foundation for applying the technology to practical wastewaters.
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Affiliation(s)
- Ling-Dong Shi
- MOE Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Science, Zhejiang University, Hangzhou, 310058, China; Zhejiang Prov Key Lab Water Pollut Control & Envi, Zhejiang University, Hangzhou, Zhejiang, China
| | - Pan-Long Lv
- MOE Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Science, Zhejiang University, Hangzhou, 310058, China; Zhejiang Prov Key Lab Water Pollut Control & Envi, Zhejiang University, Hangzhou, Zhejiang, China
| | - Zi-Fan Niu
- MOE Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Science, Zhejiang University, Hangzhou, 310058, China; Zhejiang Prov Key Lab Water Pollut Control & Envi, Zhejiang University, Hangzhou, Zhejiang, China
| | - Chun-Yu Lai
- MOE Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Science, Zhejiang University, Hangzhou, 310058, China
| | - He-Ping Zhao
- MOE Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Science, Zhejiang University, Hangzhou, 310058, China; Zhejiang Prov Key Lab Water Pollut Control & Envi, Zhejiang University, Hangzhou, Zhejiang, China.
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46
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Merino N, Kawai M, Boyd ES, Colman DR, McGlynn SE, Nealson KH, Kurokawa K, Hongoh Y. Single-Cell Genomics of Novel Actinobacteria With the Wood-Ljungdahl Pathway Discovered in a Serpentinizing System. Front Microbiol 2020; 11:1031. [PMID: 32655506 PMCID: PMC7325909 DOI: 10.3389/fmicb.2020.01031] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 04/27/2020] [Indexed: 01/04/2023] Open
Abstract
Serpentinite-hosted systems represent modern-day analogs of early Earth environments. In these systems, water-rock interactions generate highly alkaline and reducing fluids that can contain hydrogen, methane, and low-molecular-weight hydrocarbons-potent reductants capable of fueling microbial metabolism. In this study, we investigated the microbiota of Hakuba Happo hot springs (∼50°C; pH∼10.5-11), located in Nagano (Japan), which are impacted by the serpentinization process. Analysis of the 16S rRNA gene amplicon sequences revealed that the bacterial community comprises Nitrospirae (47%), "Parcubacteria" (19%), Deinococcus-Thermus (16%), and Actinobacteria (9%), among others. Notably, only 57 amplicon sequence variants (ASV) were detected, and fifteen of these accounted for 90% of the amplicons. Among the abundant ASVs, an early-branching, uncultivated actinobacterial clade identified as RBG-16-55-12 in the SILVA database was detected. Ten single-cell genomes (average pairwise nucleotide identity: 0.98-1.00; estimated completeness: 33-93%; estimated genome size: ∼2.3 Mb) that affiliated with this clade were obtained. Taxonomic classification using single copy genes indicates that the genomes belong to the actinobacterial class-level clade UBA1414 in the Genome Taxonomy Database. Based on metabolic pathway predictions, these actinobacteria are anaerobes, capable of glycolysis, dissimilatory nitrate reduction and CO2 fixation via the Wood-Ljungdahl (WL) pathway. Several other genomes within UBA1414 and two related class-level clades also encode the WL pathway, which has not yet been reported for the Actinobacteria phylum. For the Hakuba actinobacterium, the energy metabolism related to the WL pathway is likely supported by a combination of the Rnf complex, group 3b and 3d [NiFe]-hydrogenases, [FeFe]-hydrogenases, and V-type (H+/Na+ pump) ATPase. The genomes also harbor a form IV ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) complex, also known as a RubisCO-like protein, and contain signatures of interactions with viruses, including clustered regularly interspaced short palindromic repeat (CRISPR) regions and several phage integrases. This is the first report and detailed genome analysis of a bacterium within the Actinobacteria phylum capable of utilizing the WL pathway. The Hakuba actinobacterium is a member of the clade UBA1414/RBG-16-55-12, formerly within the group "OPB41." We propose to name this bacterium 'Candidatus Hakubanella thermoalkaliphilus.'
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Affiliation(s)
- Nancy Merino
- Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan.,Department of Earth Sciences, University of Southern California, Los Angeles, CA, United States.,Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA, United States
| | - Mikihiko Kawai
- School of Life Sciences and Technology, Tokyo Institute of Technology, Tokyo, Japan.,Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan
| | - Eric S Boyd
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT, United States
| | - Daniel R Colman
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT, United States
| | - Shawn E McGlynn
- Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan.,Biofunctional Catalyst Research Team, RIKEN Center for Sustainable Resource Science, Saitama, Japan.,Blue Marble Space Institute of Science, Seattle, WA, United States
| | - Kenneth H Nealson
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, United States
| | - Ken Kurokawa
- Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan.,Department of Informatics, National Institute of Genetics, Shizuoka, Japan
| | - Yuichi Hongoh
- Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan.,School of Life Sciences and Technology, Tokyo Institute of Technology, Tokyo, Japan
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47
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Sabuda MC, Brazelton WJ, Putman LI, McCollom TM, Hoehler TM, Kubo MDY, Cardace D, Schrenk MO. A dynamic microbial sulfur cycle in a serpentinizing continental ophiolite. Environ Microbiol 2020; 22:2329-2345. [PMID: 32249550 DOI: 10.1111/1462-2920.15006] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2019] [Revised: 03/19/2020] [Accepted: 03/30/2020] [Indexed: 12/11/2022]
Abstract
Serpentinization is the hydration and oxidation of ultramafic rock, which occurs as oceanic lithosphere is emplaced onto continental margins (ophiolites), and along the seafloor as faulting exposes this mantle-derived material to circulating hydrothermal fluids. This process leads to distinctive fluid chemistries as molecular hydrogen (H2 ) and hydroxyl ions (OH- ) are produced and reduced carbon compounds are mobilized. Serpentinizing ophiolites also serve as a vector to transport sulfur compounds from the seafloor onto the continents. We investigated hyperalkaline, sulfur-rich, brackish groundwater in a serpentinizing continental ophiolite to elucidate the role of sulfur compounds in fuelling in situ microbial activities. Here we illustrate that key sulfur-cycling taxa, including Dethiobacter, Desulfitispora and 'Desulforudis', persist throughout this extreme environment. Biologically catalysed redox reactions involving sulfate, sulfide and intermediate sulfur compounds are thermodynamically favourable in the groundwater, which indicates they may be vital to sustaining life in these characteristically oxidant- and energy-limited systems. Furthermore, metagenomic and metatranscriptomic analyses reveal a complex network involving sulfate reduction, sulfide oxidation and thiosulfate reactions. Our findings highlight the importance of the complete inorganic sulfur cycle in serpentinizing fluids and suggest sulfur biogeochemistry provides a key link between terrestrial serpentinizing ecosystems and their submarine heritage.
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Affiliation(s)
- Mary C Sabuda
- Department of Earth and Environmental Sciences, Michigan State University, East Lansing, MI, 48824, USA
| | | | - Lindsay I Putman
- Department of Earth and Environmental Sciences, Michigan State University, East Lansing, MI, 48824, USA.,Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, 48824, USA
| | - Tom M McCollom
- Laboratory for Atmospheric and Space Physics, UCB 600, University of Colorado-Boulder, Boulder, CO, 80309, USA
| | - Tori M Hoehler
- Exobiology Branch, NASA Ames Research Center, Moffett Field, CA, 94035, USA
| | - Michael D Y Kubo
- Exobiology Branch, NASA Ames Research Center, Moffett Field, CA, 94035, USA.,SETI Institute, Mountain View, CA, 94043, USA
| | - Dawn Cardace
- Department of Geosciences, University of Rhode Island, Kingston, RI, 02881, USA
| | - Matthew O Schrenk
- Department of Earth and Environmental Sciences, Michigan State University, East Lansing, MI, 48824, USA.,Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, 48824, USA
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48
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Templeton AS, Ellison ET. Formation and loss of metastable brucite: does Fe(II)-bearing brucite support microbial activity in serpentinizing ecosystems? PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2020; 378:20180423. [PMID: 31902337 PMCID: PMC7015309 DOI: 10.1098/rsta.2018.0423] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/30/2019] [Indexed: 05/23/2023]
Abstract
Ultramafic rocks undergo successive stages of hydration and oxidation during water/rock interaction, giving rise to secondary minerals such as brucite, serpentine, magnetite and the production of H2(g). Ferroan brucite (MgxFe(1-x)2+(OH)2) often forms under low water/rock ratios early during the 'serpentinization' process. The formation of ferroan brucite sequesters Fe(II) and suppresses the production of H2, thereby limiting the flux of reductants suitable for sustaining microbial metabolism. Yet ferroan brucite is a relatively soluble mineral 'reservoir' for reactive Fe(II). Brucite is often metastable and can be lost at later stages of peridotite hydration when there is a significant increase in the water/rock ratio or the activity of SiO2 or CO2. The Fe(OH)2 component of brucite has the thermodynamic potential to reduce most aqueous oxidants. Therefore, ferroan brucite may reduce water and/or dissolved carbon, nitrogen and sulfur species, while the Fe(II) is converted into more stable secondary minerals such as Fe(II/III)-oxides and hydroxides (e.g. green-rust, magnetite, iowaite and pyroaurite) and ferric serpentine. The reactivity of ferroan brucite, and the associated rate of Fe solubilization and oxidation in subsurface fluids, could be a key regulator on the rate of electron transfer from serpentinites to the rock-hosted biosphere. Aqueous alteration of ferroan brucite may significantly modulate the H2 activity in fluids circulating within partially serpentinized rocks, and buffer H2 as it is lost by advection or in situ consumption by a hydrogenotrophic microbial community. Moreover, there may be microbial organisms that specifically colonize and use ferroan brucite as an electron donor for their metabolism. The energy fluxes sustained by localized brucite oxidation may often be sufficiently large to sustain abundant microbial communities; water/rock reaction zones where brucite is consumed could serve as environments to search for extant or fossil serpentinite-hosted life. This article is part of a discussion meeting issue 'Serpentinite in the Earth System'.
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Boyd ES, Amenabar MJ, Poudel S, Templeton AS. Bioenergetic constraints on the origin of autotrophic metabolism. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2020; 378:20190151. [PMID: 31902344 PMCID: PMC7015307 DOI: 10.1098/rsta.2019.0151] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/02/2019] [Indexed: 06/07/2023]
Abstract
Autotrophs form the base of all complex food webs and seemingly have done so since early in Earth history. Phylogenetic evidence suggests that early autotrophs were anaerobic, used CO2 as both an oxidant and carbon source, were dependent on H2 as an electron donor, and used iron-sulfur proteins (termed ferredoxins) as a primary electron carrier. However, the reduction potential of H2 is not typically low enough to efficiently reduce ferredoxin. Instead, in modern strictly anaerobic and H2-dependent autotrophs, ferredoxin reduction is accomplished using one of several recently evolved enzymatic mechanisms, including electron bifurcating and coupled ion translocating mechanisms. These observations raise the intriguing question of why anaerobic autotrophs adopted ferredoxins as central electron carriers only to have to evolve complex machinery to reduce them. Here, we report calculated reduction potentials for H2 as a function of observed environmental H2 concentration, pH and temperature. Results suggest that a combination of alkaline pH and high H2 concentration yield H2 reduction potentials low enough to efficiently reduce ferredoxins. Hyperalkaline, H2 rich environments have existed in discrete locations throughout Earth history where ultramafic minerals are undergoing hydration through the process of serpentinization. These results suggest that serpentinizing systems, which would have been common on early Earth, naturally produced conditions conducive to the emergence of H2-dependent autotrophic life. The primitive process of hydrogenotrophic methanogenesis is used to examine potential changes in methanogenesis and Fd reduction pathways as these organisms diversified away from serpentinizing environments. This article is part of a discussion meeting issue 'Serpentinite in the earth system'.
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Affiliation(s)
- Eric S. Boyd
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
| | | | - Saroj Poudel
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
| | - Alexis S. Templeton
- Department of Geological Sciences, University of Colorado, Boulder, CO 80309, USA
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Onstott T, Ehlmann B, Sapers H, Coleman M, Ivarsson M, Marlow J, Neubeck A, Niles P. Paleo-Rock-Hosted Life on Earth and the Search on Mars: A Review and Strategy for Exploration. ASTROBIOLOGY 2019; 19:1230-1262. [PMID: 31237436 PMCID: PMC6786346 DOI: 10.1089/ast.2018.1960] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Accepted: 04/25/2019] [Indexed: 05/19/2023]
Abstract
Here we review published studies on the abundance and diversity of terrestrial rock-hosted life, the environments it inhabits, the evolution of its metabolisms, and its fossil biomarkers to provide guidance in the search for life on Mars. Key findings are (1) much terrestrial deep subsurface metabolic activity relies on abiotic energy-yielding fluxes and in situ abiotic and biotic recycling of metabolic waste products rather than on buried organic products of photosynthesis; (2) subsurface microbial cell concentrations are highest at interfaces with pronounced chemical redox gradients or permeability variations and do not correlate with bulk host rock organic carbon; (3) metabolic pathways for chemolithoautotrophic microorganisms evolved earlier in Earth's history than those of surface-dwelling phototrophic microorganisms; (4) the emergence of the former occurred at a time when Mars was habitable, whereas the emergence of the latter occurred at a time when the martian surface was not continually habitable; (5) the terrestrial rock record has biomarkers of subsurface life at least back hundreds of millions of years and likely to 3.45 Ga with several examples of excellent preservation in rock types that are quite different from those preserving the photosphere-supported biosphere. These findings suggest that rock-hosted life would have been more likely to emerge and be preserved in a martian context. Consequently, we outline a Mars exploration strategy that targets subsurface life and scales spatially, focusing initially on identifying rocks with evidence for groundwater flow and low-temperature mineralization, then identifying redox and permeability interfaces preserved within rock outcrops, and finally focusing on finding minerals associated with redox reactions and associated traces of carbon and diagnostic chemical and isotopic biosignatures. Using this strategy on Earth yields ancient rock-hosted life, preserved in the fossil record and confirmable via a suite of morphologic, organic, mineralogical, and isotopic fingerprints at micrometer scale. We expect an emphasis on rock-hosted life and this scale-dependent strategy to be crucial in the search for life on Mars.
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Affiliation(s)
- T.C. Onstott
- Department of Geosciences, Princeton University, Princeton, New Jersey, USA
- Address correspondence to: T.C. Onstott, Department of Geosciences, Princeton University,, Princeton, NJ 008544
| | - B.L. Ehlmann
- Division of Geological & Planetary Sciences, California Institute of Technology, Pasadena, California, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
- B.L. Ehlmann, Division of Geological & Planetary Sciences, California Institute of Technology, Pasadena, CA 91125
| | - H. Sapers
- Division of Geological & Planetary Sciences, California Institute of Technology, Pasadena, California, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
- Department of Earth Sciences, University of Southern California, Los Angeles, California, USA
| | - M. Coleman
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
- NASA Astrobiology Institute, Pasadena, California, USA
| | - M. Ivarsson
- Department of Biology, University of Southern Denmark, Odense, Denmark
| | - J.J. Marlow
- Department of Organismic & Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA
| | - A. Neubeck
- Department of Earth Sciences, Uppsala University, Uppsala, Sweden
| | - P. Niles
- Astromaterials Research and Exploration Science Division, NASA Johnson Space Center, Houston, Texas, USA
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