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Oren A. Novel insights into the diversity of halophilic microorganisms and their functioning in hypersaline ecosystems. NPJ BIODIVERSITY 2024; 3:18. [PMID: 39242694 PMCID: PMC11332174 DOI: 10.1038/s44185-024-00050-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2024] [Accepted: 06/25/2024] [Indexed: 09/09/2024]
Abstract
Our understanding of the microbial diversity inhabiting hypersaline environments, here defined as containing >100-150 g/L salts, has greatly increased in the past five years. Halophiles are found in each of the three domains of life. Many novel types have been cultivated, and metagenomics and other cultivation-independent approaches have revealed the existence of many previously unrecognized lineages. Syntrophic interactions between different phylogenetic lineages have been discovered, such as the symbiosis between members of the archaeal class Halobacteria and the 'Candidatus Nanohalarchaeota'. Metagenomics techniques also have shed light on the biogeography of halophiles, especially of the genera Salinibacter (Bacteria) and Haloquadratum and Halorubrum (Archaea). Exploration of the microbiome of hypersaline lakes led to the discovery of novel types of metabolism previously unknown to occur at high salt concentrations. Studies of environments with high concentrations of chaotropic ions such as magnesium, calcium, and lithium have refined our understanding of the limits of life.
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Affiliation(s)
- Aharon Oren
- Department of Plant and Environmental Sciences, The Institute of Life Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus, Jerusalem, 9190401, Israel.
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2
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Leung PM, Grinter R, Tudor-Matthew E, Lingford JP, Jimenez L, Lee HC, Milton M, Hanchapola I, Tanuwidjaya E, Kropp A, Peach HA, Carere CR, Stott MB, Schittenhelm RB, Greening C. Trace gas oxidation sustains energy needs of a thermophilic archaeon at suboptimal temperatures. Nat Commun 2024; 15:3219. [PMID: 38622143 PMCID: PMC11018855 DOI: 10.1038/s41467-024-47324-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 03/22/2024] [Indexed: 04/17/2024] Open
Abstract
Diverse aerobic bacteria use atmospheric hydrogen (H2) and carbon monoxide (CO) as energy sources to support growth and survival. Such trace gas oxidation is recognised as a globally significant process that serves as the main sink in the biogeochemical H2 cycle and sustains microbial biodiversity in oligotrophic ecosystems. However, it is unclear whether archaea can also use atmospheric H2. Here we show that a thermoacidophilic archaeon, Acidianus brierleyi (Thermoproteota), constitutively consumes H2 and CO to sub-atmospheric levels. Oxidation occurs across a wide range of temperatures (10 to 70 °C) and enhances ATP production during starvation-induced persistence under temperate conditions. The genome of A. brierleyi encodes a canonical CO dehydrogenase and four distinct [NiFe]-hydrogenases, which are differentially produced in response to electron donor and acceptor availability. Another archaeon, Metallosphaera sedula, can also oxidize atmospheric H2. Our results suggest that trace gas oxidation is a common trait of Sulfolobales archaea and may play a role in their survival and niche expansion, including during dispersal through temperate environments.
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Affiliation(s)
- Pok Man Leung
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia.
| | - Rhys Grinter
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia
| | - Eve Tudor-Matthew
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia
| | - James P Lingford
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia
| | - Luis Jimenez
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia
| | - Han-Chung Lee
- Monash Proteomics and Metabolomics Platform and Department of Biochemistry, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia
| | - Michael Milton
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia
| | - Iresha Hanchapola
- Monash Proteomics and Metabolomics Platform and Department of Biochemistry, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia
| | - Erwin Tanuwidjaya
- Monash Proteomics and Metabolomics Platform and Department of Biochemistry, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia
| | - Ashleigh Kropp
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia
| | - Hanna A Peach
- Geomicrobiology Research Group, Department of Geothermal Sciences, Te Pū Ao | GNS Science, Wairakei, Taupō, 3377, Aotearoa New Zealand
| | - Carlo R Carere
- Geomicrobiology Research Group, Department of Geothermal Sciences, Te Pū Ao | GNS Science, Wairakei, Taupō, 3377, Aotearoa New Zealand
- Te Tari Pūhanga Tukanga Matū | Department of Chemical and Process Engineering, Te Whare Wānanga o Waitaha | University of Canterbury, Christchurch, 8140, Aotearoa New Zealand
| | - Matthew B Stott
- Geomicrobiology Research Group, Department of Geothermal Sciences, Te Pū Ao | GNS Science, Wairakei, Taupō, 3377, Aotearoa New Zealand
- Te Kura Pūtaiao Koiora | School of Biological Sciences, Te Whare Wānanga o Waitaha | University of Canterbury, Christchurch, 8140, Aotearoa New Zealand
| | - Ralf B Schittenhelm
- Monash Proteomics and Metabolomics Platform and Department of Biochemistry, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia
| | - Chris Greening
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, VIC, 3800, Australia.
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3
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Ben Abdallah M, Chamkha M, Karray F, Sayadi S. Microbial diversity in polyextreme salt flats and their potential applications. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2024; 31:11371-11405. [PMID: 38180652 DOI: 10.1007/s11356-023-31644-9] [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: 08/30/2023] [Accepted: 12/17/2023] [Indexed: 01/06/2024]
Abstract
Recent geological, hydrochemical, and mineralogical studies performed on hypersaline salt flats have given insights into similar geo-morphologic features on Mars. These salt-encrusted depressions are widely spread across the Earth, where they are characterized by high salt concentrations, intense UV radiation, high evaporation, and low precipitation. Their surfaces are completely dry in summer; intermittent flooding occurs in winter turning them into transitory hypersaline lakes. Thanks to new approaches such as culture-dependent, culture-independent, and metagenomic-based methods, it is important to study microbial life under polyextreme conditions and understand what lives in these dynamic ecosystems and how they function. Regarding these particular features, new halophilic microorganisms have been isolated from some salt flats and identified as excellent producers of primary and secondary metabolites and granules such as halocins, enzymes, carotenoids, polyhydroxyalkanoates, and exopolysaccharides. Additionally, halophilic microorganisms are implemented in heavy metal bioremediation and hypersaline wastewater treatment. As a result, there is a growing interest in the distribution of halophilic microorganisms around the world that can be looked upon as good models to develop sustainable biotechnological processes for all fields. This review provides insights into diversity, ecology, metabolism, and genomics of halophiles in hypersaline salt flats worldwide as well as their potential uses in biotechnology.
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Affiliation(s)
- Manel Ben Abdallah
- Laboratory of Environmental Bioprocesses, Centre of Biotechnology of Sfax, BP 1177, 3018, Sfax, Tunisia.
| | - Mohamed Chamkha
- Laboratory of Environmental Bioprocesses, Centre of Biotechnology of Sfax, BP 1177, 3018, Sfax, Tunisia
| | - Fatma Karray
- Laboratory of Environmental Bioprocesses, Centre of Biotechnology of Sfax, BP 1177, 3018, Sfax, Tunisia
| | - Sami Sayadi
- Biotechnology Program, Center for Sustainable Development, College of Arts and Sciences, Qatar University, 2713, Doha, Qatar
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4
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Garvin ZK, Abades SR, Trefault N, Alfaro FD, Sipes K, Lloyd KG, Onstott TC. Prevalence of trace gas-oxidizing soil bacteria increases with radial distance from Polloquere hot spring within a high-elevation Andean cold desert. THE ISME JOURNAL 2024; 18:wrae062. [PMID: 38625060 PMCID: PMC11094475 DOI: 10.1093/ismejo/wrae062] [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: 09/26/2023] [Revised: 01/29/2024] [Accepted: 04/10/2024] [Indexed: 04/17/2024]
Abstract
High-elevation arid regions harbor microbial communities reliant on metabolic niches and flexibility to survive under biologically stressful conditions, including nutrient limitation that necessitates the utilization of atmospheric trace gases as electron donors. Geothermal springs present "oases" of microbial activity, diversity, and abundance by delivering water and substrates, including reduced gases. However, it is unknown whether these springs exhibit a gradient of effects, increasing their impact on trace gas-oxidizers in the surrounding soils. We assessed whether proximity to Polloquere, a high-altitude geothermal spring in an Andean salt flat, alters the diversity and metabolic structure of nearby soil bacterial populations compared to the surrounding cold desert. Recovered DNA and metagenomic analyses indicate that the spring represents an oasis for microbes in this challenging environment, supporting greater biomass with more diverse metabolic functions in proximal soils that declines sharply with radial distance from the spring. Despite the sharp decrease in biomass, potential rates of atmospheric hydrogen (H2) and carbon monoxide (CO) uptake increase away from the spring. Kinetic estimates suggest this activity is due to high-affinity trace gas consumption, likely as a survival strategy for energy/carbon acquisition. These results demonstrate that Polloquere regulates a gradient of diverse microbial communities and metabolisms, culminating in increased activity of trace gas-oxidizers as the influence of the spring yields to that of the regional salt flat environment. This suggests the spring holds local importance within the context of the broader salt flat and potentially represents a model ecosystem for other geothermal systems in high-altitude desert environments.
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Affiliation(s)
- Zachary K Garvin
- Department of Geosciences, Princeton University, Princeton, NJ 08544, United States
| | - Sebastián R Abades
- GEMA Center for Genomics, Ecology and Environment, Faculty of Interdisciplinary Studies, Universidad Mayor, 8580745, Santiago, Chile
| | - Nicole Trefault
- GEMA Center for Genomics, Ecology and Environment, Faculty of Interdisciplinary Studies, Universidad Mayor, 8580745, Santiago, Chile
| | - Fernando D Alfaro
- GEMA Center for Genomics, Ecology and Environment, Faculty of Interdisciplinary Studies, Universidad Mayor, 8580745, Santiago, Chile
| | - Katie Sipes
- Department of Microbiology, University of Tennessee, Knoxville, TN 37996, United States
- Department of Environmental Science, Aarhus University, 4000, Roskilde, Denmark
| | - Karen G Lloyd
- Department of Microbiology, University of Tennessee, Knoxville, TN 37996, United States
| | - Tullis C Onstott
- Department of Geosciences, Princeton University, Princeton, NJ 08544, United States
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5
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Luo ZH, Li Q, Xie YG, Lv AP, Qi YL, Li MM, Qu YN, Liu ZT, Li YX, Rao YZ, Jiao JY, Liu L, Narsing Rao MP, Hedlund BP, Evans PN, Fang Y, Shu WS, Huang LN, Li WJ, Hua ZS. Temperature, pH, and oxygen availability contributed to the functional differentiation of ancient Nitrososphaeria. THE ISME JOURNAL 2024; 18:wrad031. [PMID: 38365241 PMCID: PMC10833072 DOI: 10.1093/ismejo/wrad031] [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: 12/01/2023] [Revised: 12/13/2023] [Accepted: 12/13/2023] [Indexed: 02/18/2024]
Abstract
Ammonia-oxidizing Nitrososphaeria are among the most abundant archaea on Earth and have profound impacts on the biogeochemical cycles of carbon and nitrogen. In contrast to these well-studied ammonia-oxidizing archaea (AOA), deep-branching non-AOA within this class remain poorly characterized because of a low number of genome representatives. Here, we reconstructed 128 Nitrososphaeria metagenome-assembled genomes from acid mine drainage and hot spring sediment metagenomes. Comparative genomics revealed that extant non-AOA are functionally diverse, with capacity for carbon fixation, carbon monoxide oxidation, methanogenesis, and respiratory pathways including oxygen, nitrate, sulfur, or sulfate, as potential terminal electron acceptors. Despite their diverse anaerobic pathways, evolutionary history inference suggested that the common ancestor of Nitrososphaeria was likely an aerobic thermophile. We further surmise that the functional differentiation of Nitrososphaeria was primarily shaped by oxygen, pH, and temperature, with the acquisition of pathways for carbon, nitrogen, and sulfur metabolism. Our study provides a more holistic and less biased understanding of the diversity, ecology, and deep evolution of the globally abundant Nitrososphaeria.
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Affiliation(s)
- Zhen-Hao Luo
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, PR China
| | - Qi Li
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, PR China
| | - Yuan-Guo Xie
- Chinese Academy of Sciences, Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei 230026, PR China
| | - Ai-Ping Lv
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, PR China
| | - Yan-Ling Qi
- Chinese Academy of Sciences, Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei 230026, PR China
| | - Meng-Meng Li
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, PR China
| | - Yan-Ni Qu
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, PR China
| | - Ze-Tao Liu
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, PR China
| | - Yu-Xian Li
- Chinese Academy of Sciences, Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei 230026, PR China
| | - Yang-Zhi Rao
- Chinese Academy of Sciences, Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei 230026, PR China
| | - Jian-Yu Jiao
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, PR China
| | - Lan Liu
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, PR China
| | - Manik Prabhu Narsing Rao
- Instituto de Ciencias Aplicadas, Facultad de Ingeniería, Universidad Autónoma de Chile, Sede Talca, 3460000 Talca, Chile
| | - Brian P Hedlund
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154, United States
- Nevada Institute of Personalized Medicine, University of Nevada Las Vegas, Las Vegas, NV 89154, United States
| | - Paul N Evans
- The Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, QLD 4072, Australia
| | - Yuan Fang
- Chinese Academy of Sciences, Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei 230026, PR China
| | - Wen-Sheng Shu
- Institute of Ecological Science, Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou 510631, PR China
- Guangdong Provincial Key Laboratory of Chemical Pollution, South China Normal University, Guangzhou 510006, PR China
| | - Li-Nan Huang
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, PR China
| | - Wen-Jun Li
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, PR China
- State Key Laboratory of Desert and Oasis Ecology, Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, PR China
| | - Zheng-Shuang Hua
- Chinese Academy of Sciences, Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei 230026, PR China
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6
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Perchlorate-Coupled Carbon Monoxide (CO) Oxidation by Moorella glycerini, an Obligately Anaerobic, Thermophilic, Nickel-Dependent Carboxydotroph. Microorganisms 2023; 11:microorganisms11020462. [PMID: 36838427 PMCID: PMC9964509 DOI: 10.3390/microorganisms11020462] [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: 12/26/2022] [Revised: 02/08/2023] [Accepted: 02/08/2023] [Indexed: 02/15/2023] Open
Abstract
Many facultative and obligate anaerobes reduce perchlorate. Likewise, carbon monoxide (CO) oxidation has been documented in many aerobes, facultative anaerobes, and obligate anaerobes. A molybdenum-dependent CO dehydrogenase (Mo-CODH) and a nickel-dependent CO dehydrogenase (Ni-CODH) distinguish the former from the latter. Some Mo-dependent CO oxidizers (Mo-COX) couple CO oxidation to perchlorate reduction, but only at low concentrations of both under conditions that do not support growth in cultures. In contrast, CO-coupled perchlorate reduction has not been documented in Ni-dependent CO oxidizers (Ni-COX). To assess the potential for Ni-COX to reduce perchlorate, a model, obligately anaerobic homoacetogen, Moorella glycerini DSM 11254T, was cultivated with or without perchlorate, usiing CO or glycerol as its sole carbon and energy source. It grew with glycerol with or without perchlorate, and its maximum cell densities were only weakly affected by the perchlorate. However, when CO (at a 30% headspace concentration) was used as a carbon and energy source, perchlorate reduction supported greater cell densities and more rapid growth rates. The stoichiometry of CO uptake, perchlorate reduction, and chloride production were consistent with the cryptic pathway for perchlorate reduction with chlorite as an end product. Chloride production occurred abiologically in the medium due to a reaction between chlorite and the sulfide used as a reducing agent. These results provide the first demonstration of CO-coupled perchlorate reduction supporting growth in Ni-COX, and they provide constraints on the potential for perchlorate-coupled, anaerobic CO oxidation in engineered systems as well as terrestrial systems and hypothetical, sub-surface, serpentinite-hosted systems on Mars.
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Ni G, Lappan R, Hernández M, Santini T, Tomkins AG, Greening C. Functional basis of primary succession: Traits of the pioneer microbes. Environ Microbiol 2023; 25:171-176. [PMID: 36309943 PMCID: PMC10098604 DOI: 10.1111/1462-2920.16266] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 10/27/2022] [Indexed: 01/21/2023]
Affiliation(s)
- Gaofeng Ni
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Rachael Lappan
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Marcela Hernández
- School of Biological Sciences, University of East Anglia, Norwich, Norfolk, United Kingdom
| | - Talitha Santini
- School of Agriculture and Environment, University of Western Australia, Perth, Western Australia, Australia
| | - Andrew G Tomkins
- School of Earth, Atmosphere & Environment, Monash University, Clayton, Victoria, Australia
| | - Chris Greening
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia.,Securing Antarctica's Environmental Future, Monash University, Clayton, Victoria, Australia
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Metabolic Potential of Microbial Communities in the Hypersaline Sediments of the Bonneville Salt Flats. mSystems 2022; 7:e0084622. [PMID: 36377900 PMCID: PMC9765009 DOI: 10.1128/msystems.00846-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The Bonneville Salt Flats (BSF) appear to be entirely desolate when viewed from above, but they host rich microbial communities just below the surface salt crust. In this study, we investigated the metabolic potential of the BSF microbial ecosystem. The predicted and measured metabolic activities provide new insights into the ecosystem functions of evaporite landscapes and are an important analog for potential subsurface microbial ecosystems on ancient and modern Mars. Hypersaline and evaporite systems have been investigated previously as astrobiological analogs for Mars and other salty celestial bodies, but these studies have generally focused on aquatic systems and cultivation-dependent approaches. Here, we present an ecosystem-level examination of metabolic pathways within the shallow subsurface of evaporites. We detected aerobic and anaerobic respiration as well as methanogenesis in BSF sediments. Metagenome-assembled genomes of diverse bacteria and archaea encode a remarkable diversity of metabolic pathways, including those associated with carbon fixation, carbon monoxide oxidation, acetogenesis, methanogenesis, sulfide oxidation, denitrification, and nitrogen fixation. These results demonstrate the potential for multiple energy sources and metabolic pathways in BSF and highlight the possibility for vibrant microbial ecosystems in the shallow subsurface of evaporites. IMPORTANCE The Bonneville Salt Flats is a unique ecosystem created from 10,000 years of desiccation and serves as an important natural laboratory for the investigation of the habitability of salty, halite, and gypsum-rich environments. Here, we show that gypsum-rich mineral deposits host a surprising diversity of organisms and appear to play a key role in stimulating the microbial cycling of sulfur and nitrogen compounds. This work highlights how diverse microbial communities within the shallow subsurface sediments are capable of maintaining an active and sustainable ecosystem, even though the surface salt crust appears to be completely devoid of life.
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Wu JH, McGenity TJ, Rettberg P, Simões MF, Li WJ, Antunes A. The archaeal class Halobacteria and astrobiology: Knowledge gaps and research opportunities. Front Microbiol 2022; 13:1023625. [PMID: 36312929 PMCID: PMC9608585 DOI: 10.3389/fmicb.2022.1023625] [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: 08/20/2022] [Accepted: 09/07/2022] [Indexed: 09/19/2023] Open
Abstract
Water bodies on Mars and the icy moons of the outer solar system are now recognized as likely being associated with high levels of salt. Therefore, the study of high salinity environments and their inhabitants has become increasingly relevant for Astrobiology. Members of the archaeal class Halobacteria are the most successful microbial group living in hypersaline conditions and are recognized as key model organisms for exposure experiments. Despite this, data for the class is uneven across taxa and widely dispersed across the literature, which has made it difficult to properly assess the potential for species of Halobacteria to survive under the polyextreme conditions found beyond Earth. Here we provide an overview of published data on astrobiology-linked exposure experiments performed with members of the Halobacteria, identifying clear knowledge gaps and research opportunities.
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Affiliation(s)
- Jia-Hui Wu
- State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology (MUST), Taipa, Macau SAR, China
- China National Space Administration (CNSA), Macau Center for Space Exploration and Science, Taipa, Macau SAR, China
| | - Terry J. McGenity
- School of Life Sciences, University of Essex, Colchester, United Kingdom
| | - Petra Rettberg
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Köln, Germany
| | - Marta F. Simões
- State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology (MUST), Taipa, Macau SAR, China
- China National Space Administration (CNSA), Macau Center for Space Exploration and Science, Taipa, Macau SAR, China
| | - Wen-Jun Li
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - André Antunes
- State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology (MUST), Taipa, Macau SAR, China
- China National Space Administration (CNSA), Macau Center for Space Exploration and Science, Taipa, Macau SAR, China
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10
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Alonso-Reyes DG, Galván FS, Irazoqui JM, Amadio A, Tschoeke D, Thompson F, Albarracín VH, Farias ME. Dissecting Light Sensing and Metabolic Pathways on the Millimeter Scale in High-Altitude Modern Stromatolites. MICROBIAL ECOLOGY 2022:10.1007/s00248-022-02112-7. [PMID: 36161499 DOI: 10.1007/s00248-022-02112-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 09/13/2022] [Indexed: 06/16/2023]
Abstract
Modern non-lithifying stromatolites on the shore of the volcanic lake Socompa (SST) in the Puna are affected by several extreme conditions. The present study assesses for the first time light utilization and functional metabolic stratification of SST on a millimeter scale through shotgun metagenomics. In addition, a scanning-electron-microscopy approach was used to explore the community. The analysis on SST unveiled the profile of a photosynthetic mat, with cyanobacteria not directly exposed to light, but placed just below a high-UV-resistant community. Calvin-Benson and 3-hydroxypropinate cycles for carbon fixation were abundant in upper, oxic layers, while the Wood-Ljungdahl pathway was dominant in the deeper anoxic strata. The high abundance of genes for UV-screening and oxidant-quenching pigments and CPF (photoreactivation) in the UV-stressed layers could indicate that the zone itself works as a UV shield. There is a remarkable density of sequences associated with photoreceptors in the first two layers. Also, genetic evidence of photosynthesis split in eukaryotic (layer 1) and prokaryotic (layer 2). Photoheterotrophic bacteria, aerobic photoautotrophic bacteria, and anaerobic photoautotrophic bacteria coexist by selectively absorbing different parts of the light spectrum (blue, red, and IR respectively) at different positions of the mat. Genes for oxygen, nitrogen, and sulfur metabolism account for the microelectrode chemical data and pigment measurements performed in previous publications. We also provide here an explanation for the vertical microbial mobility within the SST described previously. Finally, our study points to SST as ideal modern analogues of ancient ST.
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Affiliation(s)
- Daniel Gonzalo Alonso-Reyes
- Laboratorio de Microbiología Ultraestructural Y Molecular, Centro Integral de Microscopía Electrónica (CIME,), CONICET-Universidad Nacional de Tucumán, Camino de Sirga s/n, Finca El Manantial, Yerba Buena (4107), San Miguel de Tucumán, Tucumán, Argentina
- Laboratorio de Investigaciones Microbiológicas de Lagunas Andinas (LIMLA), Planta Piloto de Procesos Industriales y Microbiológicos (PROIMI), CCT, CONICET, Tucumán, Argentina
| | - Fátima Silvina Galván
- Laboratorio de Microbiología Ultraestructural Y Molecular, Centro Integral de Microscopía Electrónica (CIME,), CONICET-Universidad Nacional de Tucumán, Camino de Sirga s/n, Finca El Manantial, Yerba Buena (4107), San Miguel de Tucumán, Tucumán, Argentina
| | - José Matías Irazoqui
- Instituto de Investigación de La Cadena Láctea (INTA-CONICET), Rafaela, Argentina
| | - Ariel Amadio
- Instituto de Investigación de La Cadena Láctea (INTA-CONICET), Rafaela, Argentina
| | - Diogo Tschoeke
- Institute of Biology and Coppe, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Fabiano Thompson
- Institute of Biology and Coppe, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Virginia Helena Albarracín
- Laboratorio de Microbiología Ultraestructural Y Molecular, Centro Integral de Microscopía Electrónica (CIME,), CONICET-Universidad Nacional de Tucumán, Camino de Sirga s/n, Finca El Manantial, Yerba Buena (4107), San Miguel de Tucumán, Tucumán, Argentina.
- Facultad de Ciencias Naturales e Instituto Miguel Lillo, Universidad Nacional de Tucumán, Tucumán, Argentina.
| | - María Eugenia Farias
- Laboratorio de Investigaciones Microbiológicas de Lagunas Andinas (LIMLA), Planta Piloto de Procesos Industriales y Microbiológicos (PROIMI), CCT, CONICET, Tucumán, Argentina
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11
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Sorokin DY, Merkel AY, Messina E, Tugui C, Pabst M, Golyshin PN, Yakimov MM. Anaerobic carboxydotrophy in sulfur-respiring haloarchaea from hypersaline lakes. THE ISME JOURNAL 2022; 16:1534-1546. [PMID: 35132120 PMCID: PMC9123189 DOI: 10.1038/s41396-022-01206-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Revised: 01/03/2022] [Accepted: 01/27/2022] [Indexed: 05/24/2023]
Abstract
Anaerobic carboxydotrophy is a widespread catabolic trait in bacteria, with two dominant pathways: hydrogenogenic and acetogenic. The marginal mode by direct oxidation to CO2 using an external e-acceptor has only a few examples. Use of sulfidic sediments from two types of hypersaline lakes in anaerobic enrichments with CO as an e-donor and elemental sulfur as an e-acceptor led to isolation of two pure cultures of anaerobic carboxydotrophs belonging to two genera of sulfur-reducing haloarchaea: Halanaeroarchaeum sp. HSR-CO from salt lakes and Halalkaliarchaeum sp. AArc-CO from soda lakes. Anaerobic growth of extremely halophilic archaea with CO was obligatory depended on the presence of elemental sulfur as the electron acceptor and yeast extract as the carbon source. CO served as a direct electron donor and H2 was not generated from CO when cells were incubated with or without sulfur. The genomes of the isolates encode a catalytic Ni,Fe-CODH subunit CooS (distantly related to bacterial homologs) and its Ni-incorporating chaperone CooC (related to methanogenic homologs) within a single genomic locus. Similar loci were also present in a genome of the type species of Halalkaliarchaeum closely related to AArc-CO, and the ability for anaerobic sulfur-dependent carboxydotrophy was confirmed for three different strains of this genus. Moreover, similar proteins are encoded in three of the four genomes of recently described carbohydrate-utilizing sulfur-reducing haloarchaea belonging to the genus Halapricum and in two yet undescribed haloarchaeal species. Overall, this work demonstrated for the first time the potential for anaerobic sulfur-dependent carboxydotrophy in extremely halophilic archaea.
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Affiliation(s)
- Dimitry Y Sorokin
- Winogradsky Institute of Microbiology, Federal Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, Russia.
- Department of Biotechnology, Delft University of Technology, Delft, The Netherlands.
| | - Alexander Y Merkel
- Winogradsky Institute of Microbiology, Federal Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, Russia
| | - Enzo Messina
- IRBIM-CNR, Spianata S.Raineri 86, 98122, Messina, Italy
| | - Claudia Tugui
- Department of Biotechnology, Delft University of Technology, Delft, The Netherlands
| | - Martin Pabst
- Department of Biotechnology, Delft University of Technology, Delft, The Netherlands
| | - Peter N Golyshin
- School of Natural Sciences, Bangor University, Gwynedd, LL57 2UW, UK
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12
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Sorokin DY, Elcheninov AG, Khizhniak TV, Koenen M, Bale NJ, Damsté JSS, Kublanov IV. Natronocalculus amylovorans gen. nov., sp. nov., and Natranaeroarchaeum aerophilus sp. nov., dominant culturable amylolytic natronoarchaea from hypersaline soda lakes in southwestern siberia. Syst Appl Microbiol 2022; 45:126336. [DOI: 10.1016/j.syapm.2022.126336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 05/13/2022] [Accepted: 05/16/2022] [Indexed: 10/18/2022]
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13
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Greening C, Grinter R. Microbial oxidation of atmospheric trace gases. Nat Rev Microbiol 2022; 20:513-528. [PMID: 35414013 DOI: 10.1038/s41579-022-00724-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/11/2022] [Indexed: 02/06/2023]
Abstract
The atmosphere has recently been recognized as a major source of energy sustaining life. Diverse aerobic bacteria oxidize the three most abundant reduced trace gases in the atmosphere, namely hydrogen (H2), carbon monoxide (CO) and methane (CH4). This Review describes the taxonomic distribution, physiological role and biochemical basis of microbial oxidation of these atmospheric trace gases, as well as the ecological, environmental, medical and astrobiological importance of this process. Most soil bacteria and some archaea can survive by using atmospheric H2 and CO as alternative energy sources, as illustrated through genetic studies on Mycobacterium cells and Streptomyces spores. Certain specialist bacteria can also grow on air alone, as confirmed by the landmark characterization of Methylocapsa gorgona, which grows by simultaneously consuming atmospheric CH4, H2 and CO. Bacteria use high-affinity lineages of metalloenzymes, namely hydrogenases, CO dehydrogenases and methane monooxygenases, to utilize atmospheric trace gases for aerobic respiration and carbon fixation. More broadly, trace gas oxidizers enhance the biodiversity and resilience of soil and marine ecosystems, drive primary productivity in extreme environments such as Antarctic desert soils and perform critical regulatory services by mitigating anthropogenic emissions of greenhouse gases and toxic pollutants.
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Affiliation(s)
- Chris Greening
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia. .,Securing Antarctica's Environmental Future, Monash University, Clayton, Victoria, Australia. .,Centre to Impact AMR, Monash University, Clayton, Victoria, Australia.
| | - Rhys Grinter
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia.
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14
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Cowan DA, Ferrari BC, McKay CP. Out of Thin Air? Astrobiology and Atmospheric Chemotrophy. ASTROBIOLOGY 2022; 22:225-232. [PMID: 35025628 PMCID: PMC8861918 DOI: 10.1089/ast.2021.0066] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The emerging understanding of microbial trace gas chemotrophy as a metabolic strategy to support energy and carbon acquisition for microbial survival and growth has significant implications in the search for past, and even extant, life beyond Earth. The use of trace gases, including hydrogen and carbon monoxide as substrates for microbial oxidation, potentially offers a viable strategy with which to support life on planetary bodies that possess a suitable atmospheric composition, such as Mars and Titan. Here, we discuss the current state of knowledge of this process and explore its potential in the field of astrobiological exploration.
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Affiliation(s)
- Don A. Cowan
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
- Address correspondence to: Don A. Cowan, Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Building NW2, Room 3-12, Hatfield Campus, Lynnwood Road, Pretoria 0002, South Africa
| | - Belinda C. Ferrari
- School of Biotechnology and Biomolecular Sciences, Australian Centre for Astrobiology, UNSW Sydney, Randwick, Australia
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15
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García JL, Galán B. Integrating greenhouse gas capture and C1 biotechnology: a key challenge for circular economy. Microb Biotechnol 2021; 15:228-239. [PMID: 34905295 PMCID: PMC8719819 DOI: 10.1111/1751-7915.13991] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 11/27/2021] [Indexed: 12/02/2022] Open
Affiliation(s)
- José L García
- Environmental Biotechnology Laboratory, Department of Microbial and Plant Biotechnology, Centro de Investigaciones Biológicas Margarita Salas (CIB-MS, CSIC), Madrid, Spain
| | - Beatriz Galán
- Environmental Biotechnology Laboratory, Department of Microbial and Plant Biotechnology, Centro de Investigaciones Biológicas Margarita Salas (CIB-MS, CSIC), Madrid, Spain
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16
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Khivantsev K, Jaegers NR, Aleksandrov HA, Kovarik L, Derewinski MA, Wang Y, Vayssilov GN, Szanyi J. Biomimetic CO oxidation below -100 °C by a nitrate-containing metal-free microporous system. Nat Commun 2021; 12:6033. [PMID: 34654809 PMCID: PMC8519918 DOI: 10.1038/s41467-021-26157-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 09/10/2021] [Indexed: 11/16/2022] Open
Abstract
CO oxidation is of importance both for inorganic and living systems. Transition and precious metals supported on various materials can oxidize CO to CO2. Among them, few systems, such as Au/TiO2, can perform CO oxidation at temperatures as low as -70 °C. Living (an)aerobic organisms perform CO oxidation with nitrate using complex enzymes under ambient temperatures representing an essential pathway for life, which enables respiration in the absence of oxygen and leads to carbonate mineral formation. Herein, we report that CO can be oxidized to CO2 by nitrate at -140 °C within an inorganic, nonmetallic zeolitic system. The transformation of NOx and CO species in zeolite as well as the origin of this unique activity is clarified using a joint spectroscopic and computational approach.
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Affiliation(s)
| | | | | | - Libor Kovarik
- Pacific Northwest National Laboratory, Richland, WA, 99352, USA
| | - Miroslaw A Derewinski
- Pacific Northwest National Laboratory, Richland, WA, 99352, USA
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Krakow, 30-239, Poland
| | - Yong Wang
- Pacific Northwest National Laboratory, Richland, WA, 99352, USA
- Voiland School of Chemical Engineering and Bioengineering Washington State University, Pullman, WA, 99163, USA
| | - Georgi N Vayssilov
- Faculty of Chemistry and Pharmacy, University of Sofia, Sofia, 1126, Bulgaria
| | - Janos Szanyi
- Pacific Northwest National Laboratory, Richland, WA, 99352, USA.
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17
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A Review of the Phyllosilicates in Gale Crater as Detected by the CheMin Instrument on the Mars Science Laboratory, Curiosity Rover. MINERALS 2021. [DOI: 10.3390/min11080847] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Curiosity, the Mars Science Laboratory (MSL) rover, landed on Mars in August 2012 to investigate the ~3.5-billion-year-old (Ga) fluvio-lacustrine sedimentary deposits of Aeolis Mons (informally known as Mount Sharp) and the surrounding plains (Aeolis Palus) in Gale crater. After nearly nine years, Curiosity has traversed over 25 km, and the Chemistry and Mineralogy (CheMin) X-ray diffraction instrument on-board Curiosity has analyzed 30 drilled rock and three scooped soil samples to date. The principal strategic goal of the mission is to assess the habitability of Mars in its ancient past. Phyllosilicates are common in ancient Martian terrains dating to ~3.5–4 Ga and were detected from orbit in some of the lower strata of Mount Sharp. Phyllosilicates on Earth are important for harboring and preserving organics. On Mars, phyllosilicates are significant for exploration as they are hypothesized to be a marker for potential habitable environments. CheMin data demonstrate that ancient fluvio-lacustrine rocks in Gale crater contain up to ~35 wt. % phyllosilicates. Phyllosilicates are key indicators of past fluid–rock interactions, and variation in the structure and composition of phyllosilicates in Gale crater suggest changes in past aqueous environments that may have been habitable to microbial life with a variety of possible energy sources.
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18
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Thermodynamic Constraints on Smectite and Iron Oxide Formation at Gale Crater, Mars: Insights into Potential Free Energy from Aerobic Fe Oxidation in Lake Water–Groundwater Mixing Zone. MINERALS 2021. [DOI: 10.3390/min11040341] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The presence of saponite and iron oxides in Sheepbed mudstone of Yellowknife Bay at Gale crater on Mars is considered as evidence of a habitable fluvio-lacustrine environment for chemolithoautotrophy. However, the energetic availability for metabolic reactions is poorly constrained. Herein, we propose the possible mixing of surface water and groundwater that (i) explains the formation of magnetite and hematite detected in Sheepbed mudstone and (ii) may work as a potential habitable zone for aerobic Fe2+-oxidizing microbes. Our thermodynamic modeling of water–rock reactions revealed that the formation of abundant saponite in Sheepbed mudstone may occur under various conditions of water-to-rock mass ratios, temperatures (5–200 °C), and initial fluid compositions. In contrast, the formation of iron oxides in the mudstone can be explained only by the mixing of Fe2+-rich groundwater and more oxidized surface waters, where the Fe2+-rich groundwater can be generated by the low-temperature water–rock reactions with a CO2-bearing initial fluid. The calculated bioavailable energy of aerobic Fe2+ oxidation in the fluid-mixing zone on Mars is similar to that estimated for a fluid-mixing zone on Earth actually inhabited by aerobic Fe2+-oxidizing microbes. The findings will contribute to a better understanding of potential habitability on Mars.
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19
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Bonelli C, Dorador C. Endangered Salares: micro-disasters in Northern Chile. TAPUYA: LATIN AMERICAN SCIENCE, TECHNOLOGY AND SOCIETY 2021; 4:1968634. [PMID: 35252764 PMCID: PMC8887917 DOI: 10.1080/25729861.2021.1968634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
This article emerges from a transdisciplinary collaboration between a micro-biologist and an anthropologist deeply concerned with the protection of endangered salares (saltpans) in northern Chile. Our aim is to establish the concept of “micro-disaster” as a tool for examining how extractivism is disrupting salares and their “deep-time” microbial ecologies. These ecologies are key for understanding early events on Earth, as their evolution enabled the oxygenation of the planet 2.5 billion years ago and caused the biodiversity explosion. By considering how beinghuman involves beingmicroorganismal – and how human time is entangled with microorganismic time –, this article connects neoliberal extractivist history with geo-biological evolutionary history. “Micro-disasters” therefore affect us deeply as complex humans, and oblige us to develop further a planet-centered mode of collaborating, thinking, feeling, and acting. In the context of this special issue on extinction, we insist that concerns over extinction must be considered in continuity with deep-time ecologies. We propose to rethink humans as an “environmentally complex we” simultaneously entangled with historical experiential time and microbial “deep-time.”
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Affiliation(s)
| | - Cristina Dorador
- Department of Biotechnology, Universidad de Antofagasta, Antofagasta, Chile
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20
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Paul V, Banerjee Y, Ghosh P, Busi SB. Depthwise microbiome and isotopic profiling of a moderately saline microbial mat in a solar saltern. Sci Rep 2020; 10:20686. [PMID: 33244085 PMCID: PMC7693307 DOI: 10.1038/s41598-020-77622-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 11/09/2020] [Indexed: 11/23/2022] Open
Abstract
The solar salterns in Tuticorin, India, are man-made, saline to hypersaline systems hosting some uniquely adapted populations of microorganisms and eukaryotic algae that have not been fully characterized. Two visually different microbial mats (termed 'white' and 'green') developing on the reservoir ponds (53 PSU) were isolated from the salterns. Firstly, archaeal and bacterial diversity in different vertical layers of the mats were analyzed. Culture-independent 16S rRNA gene analysis revealed that both bacteria and archaea were rich in their diversity. The top layers had a higher representation of halophilic archaea Halobacteriaceae, phylum Chloroflexi, and classes Anaerolineae, Delta- and Gamma- Proteobacteria than the deeper sections, indicating that a salinity gradient exists within the mats. Limited presence of Cyanobacteria and detection of algae-associated bacteria, such as Phycisphaerae, Phaeodactylibacter and Oceanicaulis likely implied that eukaryotic algae and other phototrophs could be the primary producers within the mat ecosystem. Secondly, predictive metabolic pathway analysis using the 16S rRNA gene data revealed that in addition to the regulatory microbial functions, methane and nitrogen metabolisms were prevalent. Finally, stable carbon and nitrogen isotopic compositions determined from both mat samples showed that the δ13Corg and δ15Norg values increased slightly with depth, ranging from - 16.42 to - 14.73‰, and 11.17 to 13.55‰, respectively. The isotopic signature along the microbial mat profile followed a pattern that is distinctive to the community composition and net metabolic activities, and comparable to saline mats in other salterns. The results and discussions presented here by merging culture-independent studies, predictive metabolic analyses and isotopic characterization, provide a collective strategy to understand the compositional and functional characteristics of microbial mats in saline environments.
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Affiliation(s)
- Varun Paul
- Department of Geosciences, Mississippi State University, Starkville, MS, 39762, USA.
| | - Yogaraj Banerjee
- Interdisciplinary Centre for Water Research, Indian Institute of Science, Bangalore, 560012, India
| | - Prosenjit Ghosh
- Interdisciplinary Centre for Water Research, Indian Institute of Science, Bangalore, 560012, India
- Centre for Earth Sciences, Indian Institute of Science, Bangalore, 560012, India
| | - Susheel Bhanu Busi
- Luxembourg Centre for Systems Biomedicine, University of Luxembourg, 4362, Esch-sur-Alzette, Luxembourg
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21
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Hopper CP, De La Cruz LK, Lyles KV, Wareham LK, Gilbert JA, Eichenbaum Z, Magierowski M, Poole RK, Wollborn J, Wang B. Role of Carbon Monoxide in Host-Gut Microbiome Communication. Chem Rev 2020; 120:13273-13311. [PMID: 33089988 DOI: 10.1021/acs.chemrev.0c00586] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Nature is full of examples of symbiotic relationships. The critical symbiotic relation between host and mutualistic bacteria is attracting increasing attention to the degree that the gut microbiome is proposed by some as a new organ system. The microbiome exerts its systemic effect through a diverse range of metabolites, which include gaseous molecules such as H2, CO2, NH3, CH4, NO, H2S, and CO. In turn, the human host can influence the microbiome through these gaseous molecules as well in a reciprocal manner. Among these gaseous molecules, NO, H2S, and CO occupy a special place because of their widely known physiological functions in the host and their overlap and similarity in both targets and functions. The roles that NO and H2S play have been extensively examined by others. Herein, the roles of CO in host-gut microbiome communication are examined through a discussion of (1) host production and function of CO, (2) available CO donors as research tools, (3) CO production from diet and bacterial sources, (4) effect of CO on bacteria including CO sensing, and (5) gut microbiome production of CO. There is a large amount of literature suggesting the "messenger" role of CO in host-gut microbiome communication. However, much more work is needed to begin achieving a systematic understanding of this issue.
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Affiliation(s)
- Christopher P Hopper
- Institute for Experimental Biomedicine, University Hospital Wuerzburg, Wuerzburg, Bavaria DE 97080, Germany.,Department of Medicinal Chemistry, College of Pharmacy, The University of Florida, Gainesville, Florida 32611, United States
| | - Ladie Kimberly De La Cruz
- Department of Chemistry & Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia 30303, United States
| | - Kristin V Lyles
- Department of Biology, Georgia State University, Atlanta, Georgia 30303, United States
| | - Lauren K Wareham
- The Vanderbilt Eye Institute and Department of Ophthalmology & Visual Sciences, The Vanderbilt University Medical Center and School of Medicine, Nashville, Tennessee 37232, United States
| | - Jack A Gilbert
- Department of Pediatrics, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093, United States
| | - Zehava Eichenbaum
- Department of Biology, Georgia State University, Atlanta, Georgia 30303, United States
| | - Marcin Magierowski
- Cellular Engineering and Isotope Diagnostics Laboratory, Department of Physiology, Jagiellonian University Medical College, Cracow PL 31-531, Poland
| | - Robert K Poole
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Firth Court, Sheffield S10 2TN, U.K
| | - Jakob Wollborn
- Department of Anesthesiology and Critical Care, Medical Center, University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg DE 79085, Germany.,Department of Anesthesiology, Perioperative and Pain Management, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Binghe Wang
- Department of Chemistry & Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia 30303, United States
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Liggan LM, Martone PT. Gas Composition of Developing Pneumatocysts in Bull Kelp Nereocystis luetkeana (Phaeophyceae) 1. JOURNAL OF PHYCOLOGY 2020; 56:1367-1372. [PMID: 32479662 DOI: 10.1111/jpy.13037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 05/17/2020] [Indexed: 06/11/2023]
Abstract
The subtidal kelp Nereocystis luetkeana (hereafter Nereocystis) maintains an upright stature by producing a single gas-filled float (pneumatocyst) that provides buoyancy. The ability of Nereocystis pneumatocysts to inflate with gas underwater is peculiar, and the gas composition of pneumatocysts has been the topic of several studies over the last 100 years. Past studies of pneumatocyst gases only examined large sporophytes, leaving open questions about the origins of these gases and how gas composition may change during development. In this study, we use developmental time as a means to understand the origin and physiological mechanisms that give rise to different gases within Nereocystis pneumatocysts. Total gas composition was measured across a range of pneumatocyst sizes (5-725 mL). Contrary to previous studies that documented pneumatocyst gas concentrations to be similar to air, this study found internal gas levels of CO, CO2 , and O2 to be 1.2 ± 0.8%, 0.6 ± 0.2%, and 59.9 ± 13.6%, respectively. Our data suggest that the composition of gases does not change as pneumatocysts grow and that the rate of each gas added is approximately proportional to changes in pneumatocyst volume. Therefore, cells constituting the pneumatocyst wall are likely producing more gas (per surface area) to fill pneumatocysts as they expand, maintaining proportional gas composition and corresponding internal pressure.
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Affiliation(s)
- Lauran M Liggan
- Department of Botany and Biodiversity Research Centre, University of British Columbia, 3529-6270 University Blvd, Vancouver, BC, V6T 1Z4, Canada
| | - Patrick T Martone
- Department of Botany and Biodiversity Research Centre, University of British Columbia, 3529-6270 University Blvd, Vancouver, BC, V6T 1Z4, Canada
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23
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Sorokin DY, Diender M, Merkel AY, Koenen M, Bale NJ, Pabst M, Sinninghe Damsté JS, Sousa DZ. Natranaerofaba carboxydovora gen. nov., sp. nov., an extremely haloalkaliphilic CO-utilizing acetogen from a hypersaline soda lake representing a novel deep phylogenetic lineage in the class 'Natranaerobiia'. Environ Microbiol 2020; 23:3460-3476. [PMID: 32955149 PMCID: PMC8359318 DOI: 10.1111/1462-2920.15241] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 09/15/2020] [Accepted: 09/17/2020] [Indexed: 01/02/2023]
Abstract
An anaerobic enrichment with CO from sediments of hypersaline soda lakes resulted in a methane‐forming binary culture, whereby CO was utilized by a bacterium and not the methanogenic partner. The bacterial isolate ANCO1 forms a deep‐branching phylogenetic lineage at the level of a new family within the class ‘Natranaerobiia’. It is an extreme haloalkaliphilic and moderate thermophilic acetogen utilizing CO, formate, pyruvate and lactate as electron donors and thiosulfate, nitrate (reduced to ammonia) and fumarate as electron acceptors. The genome of ANCO1 encodes a full Wood–Ljungdahl pathway allowing for CO oxidation and acetogenic conversion of pyruvate. A locus encoding Nap nitrate reductase/NrfA ammonifying nitrite reductase is also present. Thiosulfate respiration is encoded by a Phs/Psr‐like operon. The organism obviously relies on Na‐based bioenergetics, since the genome encodes for the Na+‐Rnf complex, Na+‐F1F0 ATPase and Na+‐translocating decarboxylase. Glycine betaine serves as a compatible solute. ANCO1 has an unusual membrane polar lipid composition dominated by diethers, more common among archaea, probably a result of adaptation to multiple extremophilic conditions. Overall, ANCO1 represents a unique example of a triple extremophilic CO‐oxidizing anaerobe and is classified as a novel genus and species Natranaerofaba carboxydovora in a novel family Natranaerofabacea.
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Affiliation(s)
- Dimitry Y Sorokin
- Winogradsky Institute of Microbiology, Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, Russia.,Department of Biotechnology, Delft University of Technology, Delft, The Netherlands
| | - Martijn Diender
- Laboratory of Microbiology, Wageningen University, Wageningen, The Netherlands
| | - Alexander Y Merkel
- Winogradsky Institute of Microbiology, Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, Russia
| | - Michel Koenen
- NIOZ Royal Netherlands Institute for Sea Research, Department of Marine Microbiology and Biogeochemistry, Utrecht University, Den Burg, The Netherlands
| | - Nicole J Bale
- NIOZ Royal Netherlands Institute for Sea Research, Department of Marine Microbiology and Biogeochemistry, Utrecht University, Den Burg, The Netherlands
| | - Martin Pabst
- Department of Biotechnology, Delft University of Technology, Delft, The Netherlands
| | - Jaap S Sinninghe Damsté
- NIOZ Royal Netherlands Institute for Sea Research, Department of Marine Microbiology and Biogeochemistry, Utrecht University, Den Burg, The Netherlands.,Department of Geosciences, Utrecht University, Utrecht, The Netherlands
| | - Diana Z Sousa
- Laboratory of Microbiology, Wageningen University, Wageningen, The Netherlands
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24
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Wong HL, MacLeod FI, White RA, Visscher PT, Burns BP. Microbial dark matter filling the niche in hypersaline microbial mats. MICROBIOME 2020; 8:135. [PMID: 32938503 PMCID: PMC7495880 DOI: 10.1186/s40168-020-00910-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 08/19/2020] [Indexed: 05/08/2023]
Abstract
BACKGROUND Shark Bay, Australia, harbours one of the most extensive and diverse systems of living microbial mats that are proposed to be analogs of some of the earliest ecosystems on Earth. These ecosystems have been shown to possess a substantial abundance of uncultivable microorganisms. These enigmatic microbes, jointly coined as 'microbial dark matter' (MDM), are hypothesised to play key roles in modern microbial mats. RESULTS We reconstructed 115 metagenome-assembled genomes (MAGs) affiliated to MDM, spanning 42 phyla. This study reports for the first time novel microorganisms (Zixibacterial order GN15) putatively taking part in dissimilatory sulfate reduction in surface hypersaline settings, as well as novel eukaryote signature proteins in the Asgard archaea. Despite possessing reduced-size genomes, the MDM MAGs are capable of fermenting and degrading organic carbon, suggesting a role in recycling organic carbon. Several forms of RuBisCo were identified, allowing putative CO2 incorporation into nucleotide salvaging pathways, which may act as an alternative carbon and phosphorus source. High capacity of hydrogen production was found among Shark Bay MDM. Putative schizorhodopsins were also identified in Parcubacteria, Asgard archaea, DPANN archaea, and Bathyarchaeota, allowing these members to potentially capture light energy. Diversity-generating retroelements were prominent in DPANN archaea that likely facilitate the adaptation to a dynamic, host-dependent lifestyle. CONCLUSIONS This is the first study to reconstruct and describe in detail metagenome-assembled genomes (MAGs) affiliated with microbial dark matter in hypersaline microbial mats. Our data suggests that these microbial groups are major players in these systems. In light of our findings, we propose H2, ribose and CO/CO2 as the main energy currencies of the MDM community in these mat systems. Video Abstract.
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Affiliation(s)
- Hon Lun Wong
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, 2052, Australia
- Australian Centre for Astrobiology, University of New South Wales, Sydney, Australia
| | - Fraser I MacLeod
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, 2052, Australia
- Australian Centre for Astrobiology, University of New South Wales, Sydney, Australia
| | - Richard Allen White
- Australian Centre for Astrobiology, University of New South Wales, Sydney, Australia
- RAW Molecular Systems LLC, Spokane, WA, USA
- Department of Bioinformatics and Genomics, The University of North Carolina, Charlotte, NC, USA
| | - Pieter T Visscher
- Australian Centre for Astrobiology, University of New South Wales, Sydney, Australia
- Department of Marine Sciences, University of Connecticut, Mansfield, USA
- Biogeosciences, the Université de Bourgogne Franche-Comté, Dijon, France
| | - Brendan P Burns
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, 2052, Australia.
- Australian Centre for Astrobiology, University of New South Wales, Sydney, Australia.
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25
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Abstract
The brines of natural salt lakes with total salt concentrations exceeding 30% are often colored red by dense communities of halophilic microorganisms. Such red brines are found in the north arm of Great Salt Lake, Utah, in the alkaline hypersaline lakes of the African Rift Valley, and in the crystallizer ponds of coastal and inland salterns where salt is produced by evaporation of seawater or some other source of saline water. Red blooms were also reported in the Dead Sea in the past. Different types of pigmented microorganisms may contribute to the coloration of the brines. The most important are the halophilic archaea of the class Halobacteria that contain bacterioruberin carotenoids as well as bacteriorhodopsin and other retinal pigments, β-carotene-rich species of the unicellular green algal genus Dunaliella and bacteria of the genus Salinibacter (class Rhodothermia) that contain the carotenoid salinixanthin and the retinal protein xanthorhodopsin. Densities of prokaryotes in red brines often exceed 2-3×107 cells/mL. I here review the information on the biota of the red brines, the interactions between the organisms present, as well as the possible roles of the red halophilic microorganisms in the salt production process and some applied aspects of carotenoids and retinal proteins produced by the different types of halophiles inhabiting the red brines.
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Affiliation(s)
- Aharon Oren
- The Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel.
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26
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Borer B, Jimenez-Martinez J, Stocker R, Or D. Reduced gravity promotes bacterially mediated anoxic hotspots in unsaturated porous media. Sci Rep 2020; 10:8614. [PMID: 32451389 PMCID: PMC7248055 DOI: 10.1038/s41598-020-65362-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Accepted: 04/30/2020] [Indexed: 11/23/2022] Open
Abstract
Human endeavours into deep space exploration and the prospects of establishing colonies on nearby planets would invariably involve components of bioregenerative life support for food production, cabin atmosphere renewal, and waste recycling. Growing plants and their microbiomes in porous media under different gravitational fields may present new challenges due to effects of liquid distribution on gaseous exchange with roots and microorganisms. We provide the first direct evidence that capillary driven liquid reconfiguration in porous media under reduced gravity conditions reduces oxygen diffusion pathways and enhances anoxic conditions within bacterial hotspots. Parabolic flight experiments using model porous media inoculated with aerobic and facultative anaerobic bacteria reveal the systematic enhancement of anoxic conditions during the reduced gravity periods in the presence but not in the absence of bacterial activity. The promotion of anoxic conditions under reduced gravity may lead to higher nitrous oxide and methane emissions relative to Earth conditions, on the other hand, anoxic conditions could be beneficial for perchlorate bioremediation of Martian soil. The results highlight changes in soil bacterial microhabitats under reduced gravity and the challenges of managing bioregenerative life support systems in space.
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Affiliation(s)
- Benedict Borer
- Department of Environmental Systems Science, ETHZ, Zürich, Switzerland
| | - Joaquin Jimenez-Martinez
- Department of Water Resources and Drinking Water, EAWAG, Dübendorf, Switzerland. .,Department of Civil, Environmental and Geomatic Engineering, ETHZ, Zürich, Switzerland.
| | - Roman Stocker
- Department of Civil, Environmental and Geomatic Engineering, ETHZ, Zürich, Switzerland
| | - Dani Or
- Department of Environmental Systems Science, ETHZ, Zürich, Switzerland
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27
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Leung PM, Bay SK, Meier DV, Chiri E, Cowan DA, Gillor O, Woebken D, Greening C. Energetic Basis of Microbial Growth and Persistence in Desert Ecosystems. mSystems 2020; 5:e00495-19. [PMID: 32291352 PMCID: PMC7159902 DOI: 10.1128/msystems.00495-19] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Microbial life is surprisingly abundant and diverse in global desert ecosystems. In these environments, microorganisms endure a multitude of physicochemical stresses, including low water potential, carbon and nitrogen starvation, and extreme temperatures. In this review, we summarize our current understanding of the energetic mechanisms and trophic dynamics that underpin microbial function in desert ecosystems. Accumulating evidence suggests that dormancy is a common strategy that facilitates microbial survival in response to water and carbon limitation. Whereas photoautotrophs are restricted to specific niches in extreme deserts, metabolically versatile heterotrophs persist even in the hyper-arid topsoils of the Atacama Desert and Antarctica. At least three distinct strategies appear to allow such microorganisms to conserve energy in these oligotrophic environments: degradation of organic energy reserves, rhodopsin- and bacteriochlorophyll-dependent light harvesting, and oxidation of the atmospheric trace gases hydrogen and carbon monoxide. In turn, these principles are relevant for understanding the composition, functionality, and resilience of desert ecosystems, as well as predicting responses to the growing problem of desertification.
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Affiliation(s)
- Pok Man Leung
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
- Department of Microbiology, Biomedicine Discovery Institute, Clayton, Victoria, Australia
| | - Sean K Bay
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
- Department of Microbiology, Biomedicine Discovery Institute, Clayton, Victoria, Australia
| | - Dimitri V Meier
- Division of Microbial Ecology, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Eleonora Chiri
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
- Department of Microbiology, Biomedicine Discovery Institute, Clayton, Victoria, Australia
| | - Don A Cowan
- Centre for Microbial Ecology and Genomics, University of Pretoria, Hatfield, Pretoria, South Africa
| | - Osnat Gillor
- Zuckerberg Institute for Water Research, Blaustein Institutes for Desert Research, Ben Gurion University of the Negev, Sde Boker, Israel
| | - Dagmar Woebken
- Division of Microbial Ecology, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Chris Greening
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
- Department of Microbiology, Biomedicine Discovery Institute, Clayton, Victoria, Australia
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28
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McGonigle JM, Bernau JA, Bowen BB, Brazelton WJ. Robust Archaeal and Bacterial Communities Inhabit Shallow Subsurface Sediments of the Bonneville Salt Flats. mSphere 2019; 4:e00378-19. [PMID: 31462415 PMCID: PMC6714890 DOI: 10.1128/msphere.00378-19] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 08/12/2019] [Indexed: 12/31/2022] Open
Abstract
We report the first census of natural microbial communities of the Bonneville Salt Flats (BSF), a perennial salt pan at the Utah-Nevada border. Environmental DNA sequencing of archaeal and bacterial 16S rRNA genes was conducted on samples from multiple evaporite sediment layers collected from the upper 30 cm of the surface salt crust. Our results show that at the time of sampling (September 2016), BSF hosted a robust microbial community dominated by diverse halobacteria and Salinibacter species. Sequences identical to Geitlerinema sp. strain PCC 9228, an anoxygenic cyanobacterium that uses sulfide as the electron donor for photosynthesis, are also abundant in many samples. We identified taxonomic groups enriched in each layer of the salt crust sediment and revealed that the upper gypsum sediment layer found immediately under the uppermost surface halite contains a robust microbial community. In these sediments, we found an increased presence of Thermoplasmatales, Hadesarchaeota, Nanoarchaeaeota, Acetothermia, Desulfovermiculus, Halanaerobiales, Bacteroidetes, and Rhodovibrio This study provides insight into the diversity, spatial heterogeneity, and geologic context of a surprisingly complex microbial ecosystem within this macroscopically sterile landscape.IMPORTANCE Pleistocene Lake Bonneville, which covered a third of Utah, desiccated approximately 13,000 years ago, leaving behind the Bonneville Salt Flats (BSF) in the Utah West Desert. The potash salts that saturate BSF basin are extracted and sold as an additive for agricultural fertilizers. The salt crust is a well-known recreational and economic commodity, but the biological interactions with the salt crust have not been studied. This study is the first geospatial analysis of microbially diverse populations at this site using cultivation-independent environmental DNA sequencing methods. Identification of the microbes present within this unique, dynamic, and valued sedimentary evaporite environment is an important step toward understanding the potential consequences of perturbations to the microbial ecology on the surrounding landscape and ecosystem.
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Affiliation(s)
- Julia M McGonigle
- School of Biological Sciences, University of Utah, Salt Lake City, Utah, USA
| | - Jeremiah A Bernau
- Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah, USA
| | - Brenda B Bowen
- Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah, USA
| | - William J Brazelton
- School of Biological Sciences, University of Utah, Salt Lake City, Utah, USA
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29
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Atmospheric carbon monoxide oxidation is a widespread mechanism supporting microbial survival. ISME JOURNAL 2019; 13:2868-2881. [PMID: 31358912 PMCID: PMC6794299 DOI: 10.1038/s41396-019-0479-8] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 06/22/2019] [Accepted: 06/28/2019] [Indexed: 11/09/2022]
Abstract
Carbon monoxide (CO) is a ubiquitous atmospheric trace gas produced by natural and anthropogenic sources. Some aerobic bacteria can oxidize atmospheric CO and, collectively, they account for the net loss of ~250 teragrams of CO from the atmosphere each year. However, the physiological role, genetic basis, and ecological distribution of this process remain incompletely resolved. In this work, we addressed these knowledge gaps through culture-based and culture-independent work. We confirmed through shotgun proteomic and transcriptional analysis that the genetically tractable aerobic soil actinobacterium Mycobacterium smegmatis upregulates expression of a form I molydenum-copper carbon monoxide dehydrogenase by 50-fold when exhausted for organic carbon substrates. Whole-cell biochemical assays in wild-type and mutant backgrounds confirmed that this organism aerobically respires CO, including at sub-atmospheric concentrations, using the enzyme. Contrary to current paradigms on CO oxidation, the enzyme did not support chemolithoautotrophic growth and was dispensable for CO detoxification. However, it significantly enhanced long-term survival, suggesting that atmospheric CO serves a supplemental energy source during organic carbon starvation. Phylogenetic analysis indicated that atmospheric CO oxidation is widespread and an ancestral trait of CO dehydrogenases. Homologous enzymes are encoded by 685 sequenced species of bacteria and archaea, including from seven dominant soil phyla, and we confirmed genes encoding this enzyme are abundant and expressed in terrestrial and marine environments. On this basis, we propose a new survival-centric model for the evolution of aerobic CO oxidation and conclude that, like atmospheric H2, atmospheric CO is a major energy source supporting persistence of aerobic heterotrophic bacteria in deprived or changeable environments.
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30
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Two Chloroflexi classes independently evolved the ability to persist on atmospheric hydrogen and carbon monoxide. ISME JOURNAL 2019; 13:1801-1813. [PMID: 30872805 PMCID: PMC6776052 DOI: 10.1038/s41396-019-0393-0] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 01/21/2019] [Accepted: 02/20/2019] [Indexed: 11/29/2022]
Abstract
Most aerobic bacteria exist in dormant states within natural environments. In these states, they endure adverse environmental conditions such as nutrient starvation by decreasing metabolic expenditure and using alternative energy sources. In this study, we investigated the energy sources that support persistence of two aerobic thermophilic strains of the environmentally widespread but understudied phylum Chloroflexi. A transcriptome study revealed that Thermomicrobium roseum (class Chloroflexia) extensively remodels its respiratory chain upon entry into stationary phase due to nutrient limitation. Whereas primary dehydrogenases associated with heterotrophic respiration were downregulated, putative operons encoding enzymes involved in molecular hydrogen (H2), carbon monoxide (CO), and sulfur compound oxidation were significantly upregulated. Gas chromatography and microsensor experiments showed that T. roseum aerobically respires H2 and CO at a range of environmentally relevant concentrations to sub-atmospheric levels. Phylogenetic analysis suggests that the hydrogenases and carbon monoxide dehydrogenases mediating these processes are widely distributed in Chloroflexi genomes and have probably been horizontally acquired on more than one occasion. Consistently, we confirmed that the sporulating isolate Thermogemmatispora sp. T81 (class Ktedonobacteria) also oxidises atmospheric H2 and CO during persistence, though further studies are required to determine if these findings extend to mesophilic strains. This study provides axenic culture evidence that atmospheric CO supports bacterial persistence and reports the third phylum, following Actinobacteria and Acidobacteria, to be experimentally shown to mediate the biogeochemically and ecologically important process of atmospheric H2 oxidation. This adds to the growing body of evidence that atmospheric trace gases are dependable energy sources for bacterial persistence.
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31
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Xavier JC, Preiner M, Martin WF. Something special about CO-dependent CO 2 fixation. FEBS J 2018; 285:4181-4195. [PMID: 30240136 PMCID: PMC6282760 DOI: 10.1111/febs.14664] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 08/08/2018] [Accepted: 09/19/2018] [Indexed: 01/02/2023]
Abstract
Carbon dioxide enters metabolism via six known CO2 fixation pathways, of which only one is linear, exergonic in the direction of CO2‐assimilation, and present in both bacterial and archaeal anaerobes – the Wood‐Ljungdahl (WL) or reductive acetyl‐CoA pathway. Carbon monoxide (CO) plays a central role in the WL pathway as an energy rich intermediate. Here, we scan the major biochemical reaction databases for reactions involving CO and CO2. We identified 415 reactions corresponding to enzyme commission (EC) numbers involving CO2, which are non‐randomly distributed across different biochemical pathways. Their taxonomic distribution, reversibility under physiological conditions, cofactors and prosthetic groups are summarized. In contrast to CO2, only 15 reaction classes involving CO were detected. Closer inspection reveals that CO interfaces with metabolism and the carbon cycle at only two enzymes: anaerobic carbon monoxide dehydrogenase (CODH), a Ni‐ and Fe‐containing enzyme that generates CO for CO2 fixation in the WL pathway, and aerobic CODH, a Mo‐ and Cu‐containing enzyme that oxidizes environmental CO as an electron source. The CO‐dependent reaction of the WL pathway involves carbonyl insertion into a methyl carbon‐nickel at the Ni‐Fe‐S A‐cluster of acetyl‐CoA synthase (ACS). It appears that no alternative mechanisms to the CO‐dependent reaction of ACS have evolved in nearly 4 billion years, indicating an ancient and mechanistically essential role for CO at the onset of metabolism.
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Affiliation(s)
- Joana C Xavier
- Institut für Molekulare Evolution, Heinrich Heine Universität Düsseldorf, Germany
| | - Martina Preiner
- Institut für Molekulare Evolution, Heinrich Heine Universität Düsseldorf, Germany
| | - William F Martin
- Institut für Molekulare Evolution, Heinrich Heine Universität Düsseldorf, Germany.,Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
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32
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Wong HL, White RA, Visscher PT, Charlesworth JC, Vázquez-Campos X, Burns BP. Disentangling the drivers of functional complexity at the metagenomic level in Shark Bay microbial mat microbiomes. ISME JOURNAL 2018; 12:2619-2639. [PMID: 29980796 DOI: 10.1038/s41396-018-0208-8] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 04/27/2018] [Accepted: 06/01/2018] [Indexed: 11/09/2022]
Abstract
The functional metagenomic potential of Shark Bay microbial mats was examined for the first time at a millimeter scale, employing shotgun sequencing of communities via the Illumina NextSeq 500 platform in conjunction with defined chemical analyses. A detailed functional metagenomic profile has elucidated key pathways and facilitated inference of critical microbial interactions. In addition, 87 medium-to-high-quality metagenome-assembled genomes (MAG) were assembled, including potentially novel bins under the deep-branching archaeal Asgard group (Thorarchaetoa and Lokiarchaeota). A range of pathways involved in carbon, nitrogen, sulfur, and phosphorus cycles were identified in mat metagenomes, with the Wood-Ljungdahl pathway over-represented and inferred as a major carbon fixation mode. The top five sets of genes were affiliated to sulfate assimilation (cysNC cysNCD, sat), methanogenesis (hdrABC), Wood-Ljungdahl pathways (cooS, coxSML), phosphate transport (pstB), and copper efflux (copA). Polyhydroxyalkanoate (PHA) synthase genes were over-represented at the surface, with PHA serving as a potential storage of fixed carbon. Sulfur metabolism genes were highly represented, in particular complete sets of genes responsible for both assimilatory and dissimilatory sulfate reduction. Pathways of environmental adaptation (UV, hypersalinity, oxidative stress, and heavy metal resistance) were also delineated, as well as putative viral defensive mechanisms (core genes of the CRISPR, BREX, and DISARM systems). This study provides new metagenome-based models of how biogeochemical cycles and adaptive responses may be partitioned in the microbial mats of Shark Bay.
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Affiliation(s)
- Hon Lun Wong
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, Australia.,Australian Centre for Astrobiology, University of New South Wales Sydney, Sydney, NSW, Australia
| | - Richard Allen White
- Institute of Biological Chemistry, Washington State University, Pullman, USA
| | - Pieter T Visscher
- Australian Centre for Astrobiology, University of New South Wales Sydney, Sydney, NSW, Australia.,Department of Marine Sciences, University of Connecticut, Storrs, CT, USA
| | - James C Charlesworth
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, Australia.,Australian Centre for Astrobiology, University of New South Wales Sydney, Sydney, NSW, Australia
| | - Xabier Vázquez-Campos
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, Australia
| | - Brendan P Burns
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, Australia. .,Australian Centre for Astrobiology, University of New South Wales Sydney, Sydney, NSW, Australia.
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33
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Dorador C, Fink P, Hengst M, Icaza G, Villalobos AS, Vejar D, Meneses D, Zadjelovic V, Burmann L, Moelzner J, Harrod C. Microbial community composition and trophic role along a marked salinity gradient in Laguna Puilar, Salar de Atacama, Chile. Antonie van Leeuwenhoek 2018; 111:1361-1374. [PMID: 29744693 DOI: 10.1007/s10482-018-1091-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 04/23/2018] [Indexed: 10/16/2022]
Abstract
The geological, hydrological and microbiological features of the Salar de Atacama, the most extensive evaporitic sedimentary basin in the Atacama Desert of northern Chile, have been extensively studied. In contrast, relatively little attention has been paid to the composition and roles of microbial communities in hypersaline lakes which are a unique feature in the Salar. In the present study biochemical, chemical and molecular biological tools were used to determine the composition and roles of microbial communities in water, microbial mats and sediments along a marked salinity gradient in Laguna Puilar which is located in the "Los Flamencos" National Reserve. The bacterial communities at the sampling sites were dominated by members of the phyla Bacteroidetes, Chloroflexi, Cyanobacteria and Proteobacteria. Stable isotope and fatty acid analyses revealed marked variability in the composition of microbial mats at different sampling sites both horizontally (at different sites) and vertically (in the different layers). The Laguna Puilar was shown to be a microbially dominated ecosystem in which more than 60% of the fatty acids at particular sites are of bacterial origin. Our pioneering studies also suggest that the energy budgets of avian consumers (three flamingo species) and dominant invertebrates (amphipods and gastropods) use minerals as a source of energy and nutrients. Overall, the results of this study support the view that the Salar de Atacama is a heterogeneous and fragile ecosystem where small changes in environmental conditions may alter the balance of microbial communities with possible consequences at different trophic levels.
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Affiliation(s)
- Cristina Dorador
- Laboratorio de Complejidad Microbiana y Ecología Funcional, Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile. .,Departamento de Biotecnología, Facultad de Ciencias del Mar y Recursos Biológicos, Universidad de Antofagasta, Angamos 601, Antofagasta, Chile. .,Centre for Biotechnology & Bioengineering (CeBiB), Santiago, Chile.
| | - Patrick Fink
- Workgroup Aquatic Chemical Ecology, University of Cologne, Cologne Biocenter, ZülpicherStraße 47b, 50674, Cologne, Germany
| | - Martha Hengst
- Centre for Biotechnology & Bioengineering (CeBiB), Santiago, Chile.,Laboratory of Molecular Ecology and Applied Microbiology, Departamento de Ciencias Farmacéuticas, Universidad Católica del Norte, Antofagasta, Chile
| | - Gonzalo Icaza
- Laboratorio de Complejidad Microbiana y Ecología Funcional, Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile.,Centre for Biotechnology & Bioengineering (CeBiB), Santiago, Chile
| | - Alvaro S Villalobos
- Laboratorio de Complejidad Microbiana y Ecología Funcional, Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile.,Marine Microbiology, GEOMAR Helmholtz, Centre for Ocean Research Kiel, Düsternbrooker Weg 20, 24105, Kiel, Germany
| | - Drina Vejar
- Laboratorio de Complejidad Microbiana y Ecología Funcional, Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile.,Centre for Biotechnology & Bioengineering (CeBiB), Santiago, Chile
| | - Daniela Meneses
- Laboratorio de Complejidad Microbiana y Ecología Funcional, Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile.,Centre for Biotechnology & Bioengineering (CeBiB), Santiago, Chile
| | - Vinko Zadjelovic
- Laboratorio de Complejidad Microbiana y Ecología Funcional, Instituto Antofagasta, Universidad de Antofagasta, Antofagasta, Chile
| | - Lisa Burmann
- Workgroup Aquatic Chemical Ecology, University of Cologne, Cologne Biocenter, ZülpicherStraße 47b, 50674, Cologne, Germany
| | - Jana Moelzner
- Workgroup Aquatic Chemical Ecology, University of Cologne, Cologne Biocenter, ZülpicherStraße 47b, 50674, Cologne, Germany
| | - Chris Harrod
- Instituto de Ciencias Naturales Alexander von Humboldt, Facultad de Ciencias del Mar y Recursos Biológicos, Universidad de Antofagasta, Antofagasta, Chile.,Núcleo Milenio INVASAL, Concepción, Chile
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34
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McMahon S, Bosak T, Grotzinger JP, Milliken RE, Summons RE, Daye M, Newman SA, Fraeman A, Williford KH, Briggs DEG. A Field Guide to Finding Fossils on Mars. JOURNAL OF GEOPHYSICAL RESEARCH. PLANETS 2018; 123:1012-1040. [PMID: 30034979 PMCID: PMC6049883 DOI: 10.1029/2017je005478] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 03/28/2018] [Accepted: 04/23/2018] [Indexed: 05/05/2023]
Abstract
The Martian surface is cold, dry, exposed to biologically harmful radiation and apparently barren today. Nevertheless, there is clear geological evidence for warmer, wetter intervals in the past that could have supported life at or near the surface. This evidence has motivated National Aeronautics and Space Administration and European Space Agency to prioritize the search for any remains or traces of organisms from early Mars in forthcoming missions. Informed by (1) stratigraphic, mineralogical and geochemical data collected by previous and current missions, (2) Earth's fossil record, and (3) experimental studies of organic decay and preservation, we here consider whether, how, and where fossils and isotopic biosignatures could have been preserved in the depositional environments and mineralizing media thought to have been present in habitable settings on early Mars. We conclude that Noachian-Hesperian Fe-bearing clay-rich fluvio-lacustrine siliciclastic deposits, especially where enriched in silica, currently represent the most promising and best understood astropaleontological targets. Siliceous sinters would also be an excellent target, but their presence on Mars awaits confirmation. More work is needed to improve our understanding of fossil preservation in the context of other environments specific to Mars, particularly within evaporative salts and pore/fracture-filling subsurface minerals.
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Affiliation(s)
- S. McMahon
- Department of Geology and GeophysicsYale UniversityNew HavenCTUSA
- UK Centre for Astrobiology, School of Physics and AstronomyUniversity of EdinburghEdinburghUK
| | - T. Bosak
- Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of TechnologyCambridgeMAUSA
| | - J. P. Grotzinger
- Division of Geological and Planetary SciencesCalifornia Institute of TechnologyPasadenaCAUSA
| | - R. E. Milliken
- Department of Earth, Environmental and Planetary SciencesBrown UniversityProvidenceRIUSA
| | - R. E. Summons
- Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of TechnologyCambridgeMAUSA
| | - M. Daye
- Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of TechnologyCambridgeMAUSA
| | - S. A. Newman
- Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of TechnologyCambridgeMAUSA
| | - A. Fraeman
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - K. H. Williford
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - D. E. G. Briggs
- Department of Geology and GeophysicsYale UniversityNew HavenCTUSA
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35
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Price A, Pearson VK, Schwenzer SP, Miot J, Olsson-Francis K. Nitrate-Dependent Iron Oxidation: A Potential Mars Metabolism. Front Microbiol 2018; 9:513. [PMID: 29616015 PMCID: PMC5869265 DOI: 10.3389/fmicb.2018.00513] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 03/06/2018] [Indexed: 11/13/2022] Open
Abstract
This work considers the hypothetical viability of microbial nitrate-dependent Fe2+ oxidation (NDFO) for supporting simple life in the context of the early Mars environment. This draws on knowledge built up over several decades of remote and in situ observation, as well as recent discoveries that have shaped current understanding of early Mars. Our current understanding is that certain early martian environments fulfill several of the key requirements for microbes with NDFO metabolism. First, abundant Fe2+ has been identified on Mars and provides evidence of an accessible electron donor; evidence of anoxia suggests that abiotic Fe2+ oxidation by molecular oxygen would not have interfered and competed with microbial iron metabolism in these environments. Second, nitrate, which can be used by some iron oxidizing microorganisms as an electron acceptor, has also been confirmed in modern aeolian and ancient sediment deposits on Mars. In addition to redox substrates, reservoirs of both organic and inorganic carbon are available for biosynthesis, and geochemical evidence suggests that lacustrine systems during the hydrologically active Noachian period (4.1-3.7 Ga) match the circumneutral pH requirements of nitrate-dependent iron-oxidizing microorganisms. As well as potentially acting as a primary producer in early martian lakes and fluvial systems, the light-independent nature of NDFO suggests that such microbes could have persisted in sub-surface aquifers long after the desiccation of the surface, provided that adequate carbon and nitrates sources were prevalent. Traces of NDFO microorganisms may be preserved in the rock record by biomineralization and cellular encrustation in zones of high Fe2+ concentrations. These processes could produce morphological biosignatures, preserve distinctive Fe-isotope variation patterns, and enhance preservation of biological organic compounds. Such biosignatures could be detectable by future missions to Mars with appropriate instrumentation.
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Affiliation(s)
- Alex Price
- Faculty of Science, Technology, Engineering and Mathematics, The Open University, Milton Keynes, United Kingdom
| | - Victoria K. Pearson
- Faculty of Science, Technology, Engineering and Mathematics, The Open University, Milton Keynes, United Kingdom
| | - Susanne P. Schwenzer
- Faculty of Science, Technology, Engineering and Mathematics, The Open University, Milton Keynes, United Kingdom
| | - Jennyfer Miot
- CNRS, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Muséum National d’Histoire Naturelle, Université Pierre et Marie Curie – Sorbonne Universités, UMR 7590, Paris, France
| | - Karen Olsson-Francis
- Faculty of Science, Technology, Engineering and Mathematics, The Open University, Milton Keynes, United Kingdom
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Fairén AG, Parro V, Schulze-Makuch D, Whyte L. Is Searching for Martian Life a Priority for the Mars Community? ASTROBIOLOGY 2018; 18:101-107. [PMID: 29359967 PMCID: PMC5820680 DOI: 10.1089/ast.2017.1772] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 11/02/2017] [Indexed: 06/07/2023]
Affiliation(s)
- Alberto G. Fairén
- Centro de Astrobiología (CSIC-INTA), Madrid, Spain
- Department of Astronomy, Cornell University, Ithaca, New York, USA
| | - Victor Parro
- Centro de Astrobiología (CSIC-INTA), Madrid, Spain
| | - Dirk Schulze-Makuch
- Center of Astronomy and Astrophysics, Technical University Berlin, Berlin, Germany
- School of the Environment, Washington State University, Pullman, Washington, USA
| | - Lyle Whyte
- Department of Natural Resource Sciences, McGill University, Ste-Anne-de-Bellevue, Canada
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Rummel JD, Conley CA. Inadvertently Finding Earth Contamination on Mars Should Not Be a Priority for Anyone. ASTROBIOLOGY 2018; 18:108-115. [PMID: 29451824 DOI: 10.1089/ast.2017.1785] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
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Myers MR, King GM. Perchlorate-Coupled Carbon Monoxide (CO) Oxidation: Evidence for a Plausible Microbe-Mediated Reaction in Martian Brines. Front Microbiol 2017; 8:2571. [PMID: 29312249 PMCID: PMC5743682 DOI: 10.3389/fmicb.2017.02571] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 12/11/2017] [Indexed: 11/29/2022] Open
Abstract
The presence of hydrated salts on Mars indicates that some regions of its surface might be habitable if suitable metabolizable substrates are available. However, several lines of evidence have shown that Mars' regolith contains only trace levels of the organic matter needed to support heterotrophic microbes. Due to the scarcity of organic carbon, carbon monoxide (CO) at a concentration of about 700 parts per million (about 0.4 Pa) might be the single most abundant readily available substrate that could support near-surface bacterial activity. Although a variety of electron acceptors can be coupled to CO oxidation, perchlorate is likely the most abundant potential oxidant in Mars' brines. Whether perchlorate, a potent chaotrope, can support microbial CO oxidation has not been previously documented. We report here the first evidence for perchlorate-coupled CO oxidation based on assays with two distinct euryarchaeal extreme halophiles. CO oxidation occurred readily in 3.8 M NaCl brines with perchlorate concentrations from 0.01 to 1 M. Both isolates were able to couple CO with perchlorate or chlorate under anaerobic conditions with or without nitrate as an inducer for nitrate reductase, which serves as a perchlorate reductase in extreme halophiles. In the presence of perchlorate, CO concentrations were reduced to levels well below those found in Mars' atmosphere. This indicates that CO could contribute to the survival of microbial populations in hydrated salt formations or brines if water activities are suitably permissive.
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Affiliation(s)
| | - Gary M. King
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, United States
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Mickol RL, Kral TA. Low Pressure Tolerance by Methanogens in an Aqueous Environment: Implications for Subsurface Life on Mars. ORIGINS LIFE EVOL B 2017; 47:511-532. [PMID: 27663448 DOI: 10.1007/s11084-016-9519-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 09/05/2016] [Indexed: 11/26/2022]
Abstract
The low pressure at the surface of Mars (average: 6 mbar) is one potentially biocidal factor that any extant life on the planet would need to endure. Near subsurface life, while shielded from ultraviolet radiation, would also be exposed to this low pressure environment, as the atmospheric gas-phase pressure increases very gradually with depth. Few studies have focused on low pressure as inhibitory to the growth or survival of organisms. However, recent work has uncovered a potential constraint to bacterial growth below 25 mbar. The study reported here tested the survivability of four methanogen species (Methanothermobacter wolfeii, Methanosarcina barkeri, Methanobacterium formicicum, Methanococcus maripaludis) under low pressure conditions approaching average martian surface pressure (6 mbar - 143 mbar) in an aqueous environment. Each of the four species survived exposure of varying length (3 days - 21 days) at pressures down to 6 mbar. This research is an important stepping-stone to determining if methanogens can actively metabolize/grow under these low pressures. Additionally, the recently discovered recurring slope lineae suggest that liquid water columns may connect the surface to deeper levels in the subsurface. If that is the case, any organism being transported in the water column would encounter the changing pressures during the transport.
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Affiliation(s)
- R L Mickol
- Arkansas Center for Space and Planetary Sciences, University of Arkansas, Stone House North, 332 N. Arkansas Ave, Fayetteville, AR, 72701, USA.
| | - T A Kral
- Arkansas Center for Space and Planetary Sciences, University of Arkansas, Stone House North, 332 N. Arkansas Ave, Fayetteville, AR, 72701, USA
- Department of Biological Sciences, Science and Engineering 601, University of Arkansas, Fayetteville, AR, 72701, USA
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Olsson-Francis K, Pearson VK, Steer ED, Schwenzer SP. Determination of Geochemical Bio-Signatures in Mars-Like Basaltic Environments. Front Microbiol 2017; 8:1668. [PMID: 28943863 PMCID: PMC5596621 DOI: 10.3389/fmicb.2017.01668] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 08/17/2017] [Indexed: 11/28/2022] Open
Abstract
Bio-signatures play a central role in determining whether life existed on early Mars. Using a terrestrial basalt as a compositional analog for the martian surface, we applied a combination of experimental microbiology and thermochemical modeling techniques to identify potential geochemical bio-signatures for life on early Mars. Laboratory experiments were used to determine the short-term effects of biota on the dissolution of terrestrial basalt, and the formation of secondary alteration minerals. The chemoorganoheterotrophic bacterium, Burkholderia sp. strain B_33, was grown in a minimal growth medium with and without terrestrial basalt as the sole nutrient source. No growth was detected in the absence of the basalt. In the presence of basalt, during exponential growth, the pH decreased rapidly from pH 7.0 to 3.6 and then gradually increased to a steady-state of equilibrium of between 6.8 and 7.1. Microbial growth coincided with an increase in key elements in the growth medium (Si, K, Ca, Mg, and Fe). Experimental results were compared with theoretical thermochemical modeling to predict growth of secondary alteration minerals, which can be used as bio-signatures, over a geological timescale. We thermochemically modeled the dissolution of the basalt (in the absence of biota) in very dilute brine at 25°C, 1 bar; the pH was buffered by the mineral dissolution and precipitation reactions. Preliminary results suggested that at the water to rock ratio of 1 × 107, zeolite, hematite, chlorite, kaolinite, and apatite formed abiotically. The biotic weathering processes were modeled by varying the pH conditions within the model to adjust for biologic influence. The results suggested that, for a basaltic system, the microbially-mediated dissolution of basalt would result in “simpler” secondary alteration, consisting of Fe-hydroxide and kaolinite, under conditions where the abiotic system would also form chlorite. The results from this study demonstrate that, by using laboratory-based experiments and thermochemical modeling, it is possible to identify secondary alteration minerals that could potentially be used to distinguish between abiotic and biotic weathering processes on early Mars. This work will contribute to the interpretation of data from past, present, and future life detection missions to Mars.
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Affiliation(s)
- Karen Olsson-Francis
- School of Environment, Earth and Ecosystem Sciences, Open UniversityMilton Keynes, United Kingdom
| | - Victoria K Pearson
- School of Physical Sciences, Open UniversityMilton Keynes, United Kingdom
| | - Elisabeth D Steer
- School of Physical Sciences, Open UniversityMilton Keynes, United Kingdom.,Nanoscale and Microscale Research Centre, University of NottinghamNottingham, United Kingdom
| | - Susanne P Schwenzer
- School of Environment, Earth and Ecosystem Sciences, Open UniversityMilton Keynes, United Kingdom
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Stolz JF. Gaia and her microbiome. FEMS Microbiol Ecol 2016; 93:fiw247. [DOI: 10.1093/femsec/fiw247] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 10/03/2016] [Accepted: 12/07/2016] [Indexed: 01/09/2023] Open
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Halanaeroarchaeum sulfurireducens gen. nov., sp. nov., the first obligately anaerobic sulfur-respiring haloarchaeon, isolated from a hypersaline lake. Int J Syst Evol Microbiol 2016; 66:2377-2381. [DOI: 10.1099/ijsem.0.001041] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Vavourakis CD, Ghai R, Rodriguez-Valera F, Sorokin DY, Tringe SG, Hugenholtz P, Muyzer G. Metagenomic Insights into the Uncultured Diversity and Physiology of Microbes in Four Hypersaline Soda Lake Brines. Front Microbiol 2016; 7:211. [PMID: 26941731 PMCID: PMC4766312 DOI: 10.3389/fmicb.2016.00211] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 02/08/2016] [Indexed: 11/13/2022] Open
Abstract
Soda lakes are salt lakes with a naturally alkaline pH due to evaporative concentration of sodium carbonates in the absence of major divalent cations. Hypersaline soda brines harbor microbial communities with a high species- and strain-level archaeal diversity and a large proportion of still uncultured poly-extremophiles compared to neutral brines of similar salinities. We present the first "metagenomic snapshots" of microbial communities thriving in the brines of four shallow soda lakes from the Kulunda Steppe (Altai, Russia) covering a salinity range from 170 to 400 g/L. Both amplicon sequencing of 16S rRNA fragments and direct metagenomic sequencing showed that the top-level taxa abundance was linked to the ambient salinity: Bacteroidetes, Alpha-, and Gamma-proteobacteria were dominant below a salinity of 250 g/L, Euryarchaeota at higher salinities. Within these taxa, amplicon sequences related to Halorubrum, Natrinema, Gracilimonas, purple non-sulfur bacteria (Rhizobiales, Rhodobacter, and Rhodobaca) and chemolithotrophic sulfur oxidizers (Thioalkalivibrio) were highly abundant. Twenty-four draft population genomes from novel members and ecotypes within the Nanohaloarchaea, Halobacteria, and Bacteroidetes were reconstructed to explore their metabolic features, environmental abundance and strategies for osmotic adaptation. The Halobacteria- and Bacteroidetes-related draft genomes belong to putative aerobic heterotrophs, likely with the capacity to ferment sugars in the absence of oxygen. Members from both taxonomic groups are likely involved in primary organic carbon degradation, since some of the reconstructed genomes encode the ability to hydrolyze recalcitrant substrates, such as cellulose and chitin. Putative sodium-pumping rhodopsins were found in both a Flavobacteriaceae- and a Chitinophagaceae-related draft genome. The predicted proteomes of both the latter and a Rhodothermaceae-related draft genome were indicative of a "salt-in" strategy of osmotic adaptation. The primary catabolic and respiratory pathways shared among all available reference genomes of Nanohaloarchaea and our novel genome reconstructions remain incomplete, but point to a primarily fermentative lifestyle. Encoded xenorhodopsins found in most drafts suggest that light plays an important role in the ecology of Nanohaloarchaea. Putative encoded halolysins and laccase-like oxidases might indicate the potential for extracellular degradation of proteins and peptides, and phenolic or aromatic compounds.
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Affiliation(s)
- Charlotte D. Vavourakis
- Microbial Systems Ecology, Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of AmsterdamAmsterdam, Netherlands
| | - Rohit Ghai
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiología, Universidad Miguel HernándezSan Juan de Alicante, Spain
- Department of Aquatic Microbial Ecology, Biology Centre of the Czech Academy of Sciences, Institute of HydrobiologyČeské Budějovice, Czech Republic
| | - Francisco Rodriguez-Valera
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiología, Universidad Miguel HernándezSan Juan de Alicante, Spain
| | - Dimitry Y. Sorokin
- Research Centre of Biotechnology, Winogradsky Institute of Microbiology, Russian Academy of SciencesMoscow, Russia
- Department of Biotechnology, Delft University of TechnologyDelft, Netherlands
| | | | - Philip Hugenholtz
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences and Institute for Molecular Bioscience, The University of QueenslandBrisbane, QLD, Australia
| | - Gerard Muyzer
- Microbial Systems Ecology, Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of AmsterdamAmsterdam, Netherlands
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