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Viladomat Jasso M, García-Ulloa M, Zapata-Peñasco I, Eguiarte LE, Souza V. Metagenomic insight into taxonomic composition, environmental filtering and functional redundancy for shaping worldwide modern non-lithifying microbial mats. PeerJ 2024; 12:e17412. [PMID: 38827283 PMCID: PMC11144394 DOI: 10.7717/peerj.17412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 04/26/2024] [Indexed: 06/04/2024] Open
Abstract
Modern microbial mats are relictual communities mostly found in extreme environments worldwide. Despite their significance as representatives of the ancestral Earth and their important roles in biogeochemical cycling, research on microbial mats has largely been localized, focusing on site-specific descriptions and environmental change experiments. Here, we present a global comparative analysis of non-lithifying microbial mats, integrating environmental measurements with metagenomic data from 62 samples across eight sites, including two new samples from the recently discovered Archaean Domes from Cuatro Ciénegas, Mexico. Our results revealed a notable influence of environmental filtering on both taxonomic and functional compositions of microbial mats. Functional redundancy appears to confer resilience to mats, with essential metabolic pathways conserved across diverse and highly contrasting habitats. We identified six highly correlated clusters of taxa performing similar ecological functions, suggesting niche partitioning and functional specialization as key mechanisms shaping community structure. Our findings provide insights into the ecological principles governing microbial mats, and lay the foundation for future research elucidating the intricate interplay between environmental factors and microbial community dynamics.
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Affiliation(s)
- Mariette Viladomat Jasso
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | | | - Icoquih Zapata-Peñasco
- Dirección de Investigación en Transformación de Hidrocarburos, Instituto Mexicano del Petróleo, Ciudad de México, Mexico
| | - Luis E. Eguiarte
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | - Valeria Souza
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
- Centro de Estudios del Cuaternario de Fuego-Patagonia y Antártica (CEQUA), Punta Arenas, Chile
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2
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Fray D, McGovern CA, Casamatta DA, Biddanda BA, Hamsher SE. Metabarcoding reveals unique microbial mat communities and evidence of biogeographic influence in low-oxygen, high-sulfur sinkholes and springs. Ecol Evol 2024; 14:e11162. [PMID: 38529029 PMCID: PMC10961586 DOI: 10.1002/ece3.11162] [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: 10/27/2023] [Revised: 02/16/2024] [Accepted: 03/05/2024] [Indexed: 03/27/2024] Open
Abstract
High-sulfur, low-oxygen environments formed by underwater sinkholes and springs create unique habitats populated by microbial mat communities. To explore the diversity and biogeography of these mats, samples were collected from three sites in Alpena, Michigan, one site in Monroe, Michigan, and one site in Palm Coast, Florida. Our study investigated previously undescribed eukaryotic diversity in these habitats and further explored their bacterial communities. Mat samples and water parameters were collected from sulfur spring sites during the spring, summer, and fall of 2022. Cyanobacteria and diatoms were cultured from mat subsamples to create a culture-based DNA reference library. Remaining mat samples were used for metabarcoding of the 16S and rbcL regions to explore bacterial and diatom diversity, respectively. Analyses of water chemistry, alpha diversity, and beta diversity articulated a range of high-sulfur, low-oxygen habitats, each with distinct microbial communities. Conductivity, pH, dissolved oxygen, temperature, sulfate, and chloride had significant influences on community composition but did not describe the differences between communities well. Chloride concentration had the strongest correlation with microbial community structure. Mantel tests revealed that biogeography contributed to differences between communities as well. Our results provide novel information on microbial mat composition and present evidence that both local conditions and biogeography influence these unique communities.
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Affiliation(s)
- Davis Fray
- Annis Water Resources InstituteGrand Valley State UniversityMuskegonMichiganUSA
| | | | - Dale A. Casamatta
- Department of BiologyUniversity of North FloridaJacksonvilleFloridaUSA
| | - Bopaiah A. Biddanda
- Annis Water Resources InstituteGrand Valley State UniversityMuskegonMichiganUSA
| | - Sarah E. Hamsher
- Annis Water Resources InstituteGrand Valley State UniversityMuskegonMichiganUSA
- Department of BiologyGrand Valley State UniversityAllendaleMichiganUSA
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3
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Goyal A, Flamholz AI, Petroff AP, Murugan A. Closed ecosystems extract energy through self-organized nutrient cycles. Proc Natl Acad Sci U S A 2023; 120:e2309387120. [PMID: 38127977 PMCID: PMC10756307 DOI: 10.1073/pnas.2309387120] [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: 06/04/2023] [Accepted: 11/18/2023] [Indexed: 12/23/2023] Open
Abstract
Our planet is a self-sustaining ecosystem powered by light energy from the sun, but roughly closed to matter. Many ecosystems on Earth are also approximately closed to matter and recycle nutrients by self-organizing stable nutrient cycles, e.g., microbial mats, lakes, open ocean gyres. However, existing ecological models do not exhibit the self-organization and dynamical stability widely observed in such planetary-scale ecosystems. Here, we advance a conceptual model that explains the self-organization, stability, and emergent features of closed microbial ecosystems. Our model incorporates the bioenergetics of metabolism into an ecological framework. By studying this model, we uncover a crucial thermodynamic feedback loop that enables metabolically diverse communities to almost always stabilize nutrient cycles. Surprisingly, highly diverse communities self-organize to extract [Formula: see text]10[Formula: see text] of the maximum extractable energy, or [Formula: see text]100 fold more than randomized communities. Further, with increasing diversity, distinct ecosystems show strongly correlated fluxes through nutrient cycles. However, as the driving force from light increases, the fluxes of nutrient cycles become more variable and species-dependent. Our results highlight that self-organization promotes the efficiency and stability of complex ecosystems at extracting energy from the environment, even in the absence of any centralized coordination.
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Affiliation(s)
- Akshit Goyal
- Department of Physics, Massachusetts Insitute of Technology, Cambridge, MA02139
| | - Avi I. Flamholz
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA91125
- Resnick Sustainability Institute, California Institute of Technology, Pasadena, CA91125
| | | | - Arvind Murugan
- Department of Physics, University of Chicago, Chicago, IL60637
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4
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Moran JJ, Bernstein HC, Mobberley JM, Thompson AM, Kim YM, Dana KL, Cory AB, Courtney S, Renslow RS, Fredrickson JK, Kreuzer HW, Lipton MS. Daylight-driven carbon exchange through a vertically structured microbial community. Front Microbiol 2023; 14:1139213. [PMID: 37303779 PMCID: PMC10251406 DOI: 10.3389/fmicb.2023.1139213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 05/02/2023] [Indexed: 06/13/2023] Open
Abstract
Interactions between autotrophs and heterotrophs are central to carbon (C) exchange across trophic levels in essentially all ecosystems and metabolite exchange is a frequent mechanism for distributing C within spatially structured ecosystems. Yet, despite the importance of C exchange, the timescales at which fixed C is transferred in microbial communities is poorly understood. We employed a stable isotope tracer combined with spatially resolved isotope analysis to quantify photoautotrophic uptake of bicarbonate and track subsequent exchanges across a vertical depth gradient in a stratified microbial mat over a light-driven diel cycle. We observed that C mobility, both across the vertical strata and between taxa, was highest during periods of active photoautotrophy. Parallel experiments with 13C-labeled organic substrates (acetate and glucose) showed comparably less exchange of C within the mat. Metabolite analysis showed rapid incorporation of 13C into molecules that can both comprise a portion of the extracellular polymeric substances in the system and serve to transport C between photoautotrophs and heterotrophs. Stable isotope proteomic analysis revealed rapid C exchange between cyanobacterial and associated heterotrophic community members during the day with decreased exchange at night. We observed strong diel control on the spatial exchange of freshly fixed C within tightly interacting mat communities suggesting a rapid redistribution, both spatially and taxonomically, primarily during daylight periods.
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Affiliation(s)
- James J. Moran
- Pacific Northwest National Laboratory, Richland, WA, United States
- Department of Integrative Biology, Michigan State University, East Lansing, MI, United States
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI, United States
| | - Hans C. Bernstein
- Pacific Northwest National Laboratory, Richland, WA, United States
- Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, Tromsø, Norway
- ARC – The Arctic Centre for Sustainable Energy, UiT The Arctic University of Norway, Tromsø, Norway
| | | | | | - Young-Mo Kim
- Pacific Northwest National Laboratory, Richland, WA, United States
| | - Karl L. Dana
- Pacific Northwest National Laboratory, Richland, WA, United States
| | | | - Steph Courtney
- Pacific Northwest National Laboratory, Richland, WA, United States
| | - Ryan S. Renslow
- Pacific Northwest National Laboratory, Richland, WA, United States
| | | | - Helen W. Kreuzer
- Pacific Northwest National Laboratory, Richland, WA, United States
| | - Mary S. Lipton
- Pacific Northwest National Laboratory, Richland, WA, United States
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5
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Finkel PL, Carrizo D, Parro V, Sánchez-García L. An Overview of Lipid Biomarkers in Terrestrial Extreme Environments with Relevance for Mars Exploration. ASTROBIOLOGY 2023; 23:563-604. [PMID: 36880883 PMCID: PMC10150655 DOI: 10.1089/ast.2022.0083] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 01/25/2023] [Indexed: 05/03/2023]
Abstract
Lipid molecules are organic compounds, insoluble in water, and based on carbon-carbon chains that form an integral part of biological cell membranes. As such, lipids are ubiquitous in life on Earth, which is why they are considered useful biomarkers for life detection in terrestrial environments. These molecules display effective membrane-forming properties even under geochemically hostile conditions that challenge most of microbial life, which grants lipids a universal biomarker character suitable for life detection beyond Earth, where a putative biological membrane would also be required. What discriminates lipids from nucleic acids or proteins is their capacity to retain diagnostic information about their biological source in their recalcitrant hydrocarbon skeletons for thousands of millions of years, which is indispensable in the field of astrobiology given the time span that the geological ages of planetary bodies encompass. This work gathers studies that have employed lipid biomarker approaches for paleoenvironmental surveys and life detection purposes in terrestrial environments with extreme conditions: hydrothermal, hyperarid, hypersaline, and highly acidic, among others; all of which are analogous to current or past conditions on Mars. Although some of the compounds discussed in this review may be abiotically synthesized, we focus on those with a biological origin, namely lipid biomarkers. Therefore, along with appropriate complementary techniques such as bulk and compound-specific stable carbon isotope analysis, this work recapitulates and reevaluates the potential of lipid biomarkers as an additional, powerful tool to interrogate whether there is life on Mars, or if there ever was.
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Affiliation(s)
- Pablo L. Finkel
- Centro de Astrobiología (CAB), CSIC-INTA, Madrid, Spain
- Department of Physics and Mathematics and Department of Automatics, University of Alcalá, Madrid, Spain
| | | | - Victor Parro
- Centro de Astrobiología (CAB), CSIC-INTA, Madrid, Spain
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6
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Fairén AG, Rodríguez N, Sánchez-García L, Rojas P, Uceda ER, Carrizo D, Amils R, Sanz JL. Ecological successions throughout the desiccation of Tirez lagoon (Spain) as an astrobiological time-analog for wet-to-dry transitions on Mars. Sci Rep 2023; 13:1423. [PMID: 36755119 PMCID: PMC9908944 DOI: 10.1038/s41598-023-28327-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Accepted: 01/17/2023] [Indexed: 02/10/2023] Open
Abstract
Tirez was a small and seasonal endorheic athalassohaline lagoon that was located in central Spain. In recent years, the lagoon has totally dried out, offering for the first time the opportunity to analyze its desiccation process as a "time-analog" to similar events occurred in paleolakes with varying salinity during the wet-to-dry transition on early Mars. On the martian cratered highlands, an early period of water ponding within enclosed basins evolved to a complete desiccation of the lakes, leading to deposition of evaporitic sequences during the Noachian and into the Late Hesperian. As Tirez also underwent a process of desiccation, here we describe (i) the microbial ecology of Tirez when the lagoon was still active 20 years ago, with prokaryotes adapted to extreme saline conditions; (ii) the composition of the microbial community in the dried lake sediments today, in many case groups that thrive in sediments of extreme environments; and (iii) the molecular and isotopic analysis of the lipid biomarkers that can be recovered from the sediments today. We discuss the implications of these results to better understanding the ecology of possible Martian microbial communities during the wet-to-dry transition at the end of the Hesperian, and how they may inform about research strategies to search for possible biomarkers in Mars after all the water was lost.
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Affiliation(s)
- Alberto G Fairén
- Centro de Astrobiología (CSIC-INTA), 28850, Torrejón de Ardoz, Spain.
- Department of Astronomy, Cornell University, Ithaca, NY, 14853, USA.
| | - Nuria Rodríguez
- Centro de Astrobiología (CSIC-INTA), 28850, Torrejón de Ardoz, Spain
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain
| | | | - Patricia Rojas
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain
| | - Esther R Uceda
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain
| | - Daniel Carrizo
- Centro de Astrobiología (CSIC-INTA), 28850, Torrejón de Ardoz, Spain
| | - Ricardo Amils
- Centro de Astrobiología (CSIC-INTA), 28850, Torrejón de Ardoz, Spain
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain
| | - José L Sanz
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain.
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7
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Abstract
Sunlight drives phototrophic metabolism, which affects redox conditions and produces substrates for nonphototrophs. These environmental parameters fluctuate daily due to Earth’s rotation, and nonphototrophic organisms can therefore benefit from the ability to respond to, or even anticipate, such changes. Circadian rhythms, such as daily changes in body temperature, in host organisms can also affect local conditions for colonizing bacteria. Here, we investigated the effects of light/dark and temperature cycling on biofilms of the opportunistic pathogen Pseudomonas aeruginosa PA14. We grew biofilms in the presence of a respiratory indicator dye and found that enhanced dye reduction occurred in biofilm zones that formed during dark intervals and at lower temperatures. This pattern formation occurred with cycling of blue, red, or far-red light, and a screen of mutants representing potential sensory proteins identified two with defects in pattern formation, specifically under red light cycling. We also found that the physiological states of biofilm subzones formed under specific light and temperature conditions were retained during subsequent condition cycling. Light/dark and temperature cycling affected expression of genes involved in primary metabolic pathways and redox homeostasis, including those encoding electron transport chain components. Consistent with this, we found that cbb3-type oxidases contribute to dye reduction under light/dark cycling conditions. Together, our results indicate that cyclic changes in light exposure and temperature have lasting effects on redox metabolism in biofilms formed by a nonphototrophic, pathogenic bacterium.
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8
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Lingappa UF, Stein NT, Metcalfe KS, Present TM, Orphan VJ, Grotzinger JP, Knoll AH, Trower EJ, Gomes ML, Fischer WW. Early impacts of climate change on a coastal marine microbial mat ecosystem. SCIENCE ADVANCES 2022; 8:eabm7826. [PMID: 35622915 PMCID: PMC9140962 DOI: 10.1126/sciadv.abm7826] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 04/12/2022] [Indexed: 06/15/2023]
Abstract
Among the earliest consequences of climate change are extreme weather and rising sea levels-two challenges to which coastal environments are particularly vulnerable. Often found in coastal settings are microbial mats-complex, stratified microbial ecosystems that drive massive nutrient fluxes through biogeochemical cycles and have been important constituents of Earth's biosphere for eons. Little Ambergris Cay, in the Turks and Caicos Islands, supports extensive mats that vary sharply with relative water level. We characterized the microbial communities across this variation to understand better the emerging threat of sea level rise. In September 2017, the eyewall of category 5 Hurricane Irma transited the island. We monitored the impact and recovery from this devastating storm event. New mat growth proceeded rapidly, with patterns suggesting that storm perturbation may facilitate the adaptation of these ecosystems to changing sea level. Sulfur cycling, however, displayed hysteresis, stalling for >10 months after the hurricane and likely altering carbon storage potential.
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Affiliation(s)
- Usha F. Lingappa
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
| | - Nathaniel T. Stein
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
| | - Kyle S. Metcalfe
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
| | - Theodore M. Present
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
| | - Victoria J. Orphan
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
| | - John P. Grotzinger
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
| | - Andrew H. Knoll
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Elizabeth J. Trower
- Department of Geological Sciences, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Maya L. Gomes
- Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Woodward W. Fischer
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
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9
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Millimeter-scale vertical partitioning of nitrogen cycling in hypersaline mats reveals prominence of genes encoding multi-heme and prismane proteins. THE ISME JOURNAL 2022; 16:1119-1129. [PMID: 34862473 PMCID: PMC8940962 DOI: 10.1038/s41396-021-01161-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 11/09/2021] [Accepted: 11/18/2021] [Indexed: 12/01/2022]
Abstract
Microbial mats are modern analogues of the first ecosystems on the Earth. As extant representatives of microbial communities where free oxygen may have first been available on a changing planet, they offer an ecosystem within which to study the evolution of biogeochemical cycles requiring and inhibited by oxygen. Here, we report the distribution of genes involved in nitrogen metabolism across a vertical oxygen gradient at 1 mm resolution in a microbial mat using quantitative PCR (qPCR), retro-transcribed qPCR (RT-qPCR) and metagenome sequencing. Vertical patterns in the presence and expression of nitrogen cycling genes, corresponding to oxygen requiring and non-oxygen requiring nitrogen metabolism, could be seen across gradients of dissolved oxygen and ammonium. Metagenome analysis revealed that genes annotated as hydroxylamine dehydrogenase (proper enzyme designation EC 1.7.2.6, hao) and hydroxylamine reductase (hcp) were the most abundant nitrogen metabolism genes in the mat. The recovered hao genes encode hydroxylamine dehydrogenase EC 1.7.2.6 (HAO) proteins lacking the tyrosine residue present in aerobic ammonia oxidizing bacteria (AOB). Phylogenetic analysis confirmed that those proteins were more closely related to ɛHao protein present in Campylobacterota lineages (previously known as Epsilonproteobacteria) rather than oxidative HAO of AOB. The presence of hao sequences related with ɛHao protein, as well as numerous hcp genes encoding a prismane protein, suggest the presence of a nitrogen cycling pathway previously described in Nautilia profundicola as ancestral to the most commonly studied present day nitrogen cycling pathways.
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10
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Gomes ML, Klatt JM, Dick GJ, Grim SL, Rico KI, Medina M, Ziebis W, Kinsman-Costello L, Sheldon ND, Fike DA. Sedimentary pyrite sulfur isotope compositions preserve signatures of the surface microbial mat environment in sediments underlying low-oxygen cyanobacterial mats. GEOBIOLOGY 2022; 20:60-78. [PMID: 34331395 DOI: 10.1111/gbi.12466] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 07/10/2021] [Indexed: 06/13/2023]
Abstract
The sedimentary pyrite sulfur isotope (δ34 S) record is an archive of ancient microbial sulfur cycling and environmental conditions. Interpretations of pyrite δ34 S signatures in sediments deposited in microbial mat ecosystems are based on studies of modern microbial mat porewater sulfide δ34 S geochemistry. Pyrite δ34 S values often capture δ34 S signatures of porewater sulfide at the location of pyrite formation. However, microbial mats are dynamic environments in which biogeochemical cycling shifts vertically on diurnal cycles. Therefore, there is a need to study how the location of pyrite formation impacts pyrite δ34 S patterns in these dynamic systems. Here, we present diurnal porewater sulfide δ34 S trends and δ34 S values of pyrite and iron monosulfides from Middle Island Sinkhole, Lake Huron. The sediment-water interface of this sinkhole hosts a low-oxygen cyanobacterial mat ecosystem, which serves as a useful location to explore preservation of sedimentary pyrite δ34 S signatures in early Earth environments. Porewater sulfide δ34 S values vary by up to ~25‰ throughout the day due to light-driven changes in surface microbial community activity that propagate downwards, affecting porewater geochemistry as deep as 7.5 cm in the sediment. Progressive consumption of the sulfate reservoir drives δ34 S variability, instead of variations in average cell-specific sulfate reduction rates and/or sulfide oxidation at different depths in the sediment. The δ34 S values of pyrite are similar to porewater sulfide δ34 S values near the mat surface. We suggest that oxidative sulfur cycling and other microbial activity promote pyrite formation in and immediately adjacent to the microbial mat and that iron geochemistry limits further pyrite formation with depth in the sediment. These results imply that primary δ34 S signatures of pyrite deposited in organic-rich, iron-poor microbial mat environments capture information about microbial sulfur cycling and environmental conditions at the mat surface and are only minimally affected by deeper sedimentary processes during early diagenesis.
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Affiliation(s)
- Maya L Gomes
- Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - Judith M Klatt
- Microsensor Group, Max Planck Institute for Marine Microbiology, Bremen, Germany
- Department of Earth and Environmental Science, University of Michigan, Ann Arbor, MI, USA
| | - Gregory J Dick
- Department of Earth and Environmental Science, University of Michigan, Ann Arbor, MI, USA
| | - Sharon L Grim
- Department of Earth and Environmental Science, University of Michigan, Ann Arbor, MI, USA
- Exobiology Branch, National Aeronautics and Space Administration Ames Research Center, Mountain View, CA, USA
| | - Kathryn I Rico
- Department of Earth and Environmental Science, University of Michigan, Ann Arbor, MI, USA
- Department of Earth and Planetary Sciences, McGill University, Montreal, QC, Canada
| | - Matthew Medina
- Department of Earth and Environmental Science, University of Michigan, Ann Arbor, MI, USA
| | - Wiebke Ziebis
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | | | - Nathan D Sheldon
- Department of Earth and Environmental Science, University of Michigan, Ann Arbor, MI, USA
| | - David A Fike
- Department of Earth and Planetary Sciences, Washington University, Saint Louis, MO, USA
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11
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Bolay P, Hemm L, Florencio FJ, Hess WR, Muro-Pastor MI, Klähn S. The sRNA NsiR4 fine-tunes arginine synthesis in the cyanobacterium Synechocystis sp. PCC 6803 by post-transcriptional regulation of PirA. RNA Biol 2022; 19:811-818. [PMID: 35678613 PMCID: PMC9196836 DOI: 10.1080/15476286.2022.2082147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
Abstract
As the only oxygenic phototrophs among prokaryotes, cyanobacteria employ intricate mechanisms to regulate common metabolic pathways. These mechanisms include small protein inhibitors exerting their function by protein-protein interaction with key metabolic enzymes and regulatory small RNAs (sRNAs). Here we show that the sRNA NsiR4, which is highly expressed under nitrogen limiting conditions, interacts with the mRNA of the recently described small protein PirA in the model strain Synechocystis sp. PCC 6803. In particular, NsiR4 targets the pirA 5'UTR close to the ribosome binding site. Heterologous reporter assays confirmed that this interaction interferes with pirA translation. PirA negatively impacts arginine synthesis under ammonium excess by competing with the central carbon/nitrogen regulator PII that binds to and thereby activates the key enzyme of arginine synthesis, N-acetyl-L-glutamate-kinase (NAGK). Consistently, ectopic nsiR4 expression in Synechocystis resulted in lowered PirA accumulation in response to ammonium upshifts, which also affected intracellular arginine pools. As NsiR4 and PirA are inversely regulated by the global nitrogen transcriptional regulator NtcA, this regulatory axis enables fine tuning of arginine synthesis and conveys additional metabolic flexibility under highly fluctuating nitrogen regimes. Pairs of small protein inhibitors and of sRNAs that control the abundance of these enzyme effectors at the post-transcriptional level appear as fundamental building blocks in the regulation of primary metabolism in cyanobacteria.
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Affiliation(s)
- Paul Bolay
- Department of Solar Materials, Helmholtz Centre for Environmental Research, Leipzig, Germany
| | - Luisa Hemm
- Genetics and Experimental Bioinformatics, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Francisco J Florencio
- de Sevilla, Instituto de Bioquímica Vegetal Y FotosíntesisCSIC-Universidad, Sevilla, Spain
| | - Wolfgang R Hess
- Genetics and Experimental Bioinformatics, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - M Isabel Muro-Pastor
- de Sevilla, Instituto de Bioquímica Vegetal Y FotosíntesisCSIC-Universidad, Sevilla, Spain
| | - Stephan Klähn
- Department of Solar Materials, Helmholtz Centre for Environmental Research, Leipzig, Germany
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12
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Closed microbial communities self-organize to persistently cycle carbon. Proc Natl Acad Sci U S A 2021; 118:2013564118. [PMID: 34740965 PMCID: PMC8609437 DOI: 10.1073/pnas.2013564118] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/24/2021] [Indexed: 12/16/2022] Open
Abstract
Life on Earth depends on ecologically driven nutrient cycles to regenerate resources. Understanding how nutrient cycles emerge from a complex web of ecological processes is a central challenge in ecology. However, we lack model ecosystems that can be replicated, manipulated, and quantified in the laboratory, making it challenging to determine how changes in composition and the environment impact cycling. Enabled by a new high-precision method to quantify carbon cycling, we show that materially closed microbial ecosystems (CES) provided with only light self-organize to robustly cycle carbon. Studying replicate CES that support a carbon cycle reveals variable community composition but a conserved set of metabolic capabilities. Our study helps establish CES as model biospheres for studying how ecosystems persistently cycle nutrients. Cycles of nutrients (N, P, etc.) and resources (C) are a defining emergent feature of ecosystems. Cycling plays a critical role in determining ecosystem structure at all scales, from microbial communities to the entire biosphere. Stable cycles are essential for ecosystem persistence because they allow resources and nutrients to be regenerated. Therefore, a central problem in ecology is understanding how ecosystems are organized to sustain robust cycles. Addressing this problem quantitatively has proved challenging because of the difficulties associated with manipulating ecosystem structure while measuring cycling. We address this problem using closed microbial ecosystems (CES), hermetically sealed microbial consortia provided with only light. We develop a technique for quantifying carbon cycling in hermetically sealed microbial communities and show that CES composed of an alga and diverse bacterial consortia self-organize to robustly cycle carbon for months. Comparing replicates of diverse CES, we find that carbon cycling does not depend strongly on the taxonomy of the bacteria present. Moreover, despite strong taxonomic differences, self-organized CES exhibit a conserved set of metabolic capabilities. Therefore, an emergent carbon cycle enforces metabolic but not taxonomic constraints on ecosystem organization. Our study helps establish closed microbial communities as model ecosystems to study emergent function and persistence in replicate systems while controlling community composition and the environment.
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13
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Sánchez-García L, Carrizo D, Lezcano MÁ, Moreno-Paz M, Aeppli C, García-Villadangos M, Prieto-Ballesteros O, Demergasso C, Chong G, Parro V. Time-Integrative Multibiomarker Detection in Triassic-Jurassic Rocks from the Atacama Desert: Relevance to the Search for Basic Life Beyond Earth. ASTROBIOLOGY 2021; 21:1421-1437. [PMID: 34551267 DOI: 10.1089/ast.2020.2339] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Detecting evidence of life on other planetary bodies requires a certain understanding of known biomarkers and their chemical nature, preservation potential, or biological specificity. In a planetary search for life, carbonates are of special interest due to their known association with life as we know it. On Earth, carbonates serve as an invaluable paleogeochemical archive of fossils of up to billions of years old. Here, we investigated biomarker profiles on three Chilean Triassic-Jurassic sedimentary records regarding our search for signs of past and present life over ∼200 Ma. A multianalytical platform that combines lipid-derived biomarkers, metaproteomics, and a life detector chip (LDChip) is considered in the detection of biomolecules with different perdurability and source-diagnosis potential. The combined identification of proteins with positive LDChip inmunodetections provides metabolic information and taxonomic affiliation of modern/subrecent biosignatures. Molecular and isotopic analysis of more perdurable hydrocarbon cores allows for the identification of general biosources and dominant autotrophic pathways over time, as well as recreation of prevailing redox conditions over ∼200 Ma. We demonstrate how extraterrestrial life detection can benefit from the use of different biomarkers to overcome diagnosis limitations due to a lack of specificity and/or alteration over time. Our findings have implications for future astrobiological missions to Mars.
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Affiliation(s)
- Laura Sánchez-García
- Department of Molecular Evolution, Centro de Astrobiología (INTA-CSIC), Madrid, Spain
| | - Daniel Carrizo
- Department of Molecular Evolution, Centro de Astrobiología (INTA-CSIC), Madrid, Spain
| | - María Ángeles Lezcano
- Department of Molecular Evolution, Centro de Astrobiología (INTA-CSIC), Madrid, Spain
| | - Mercedes Moreno-Paz
- Department of Molecular Evolution, Centro de Astrobiología (INTA-CSIC), Madrid, Spain
| | - Christoph Aeppli
- Bigelow Laboratory for Ocean Sciences, East Boothbay, Maine, USA
| | | | | | - Cecilia Demergasso
- Department of Geological Sciences, Universidad Católica del Norte, Antofagasta, Chile
| | - Guillermo Chong
- Department of Geological Sciences, Universidad Católica del Norte, Antofagasta, Chile
| | - Victor Parro
- Department of Molecular Evolution, Centro de Astrobiología (INTA-CSIC), Madrid, Spain
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14
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Present TM, Gomes ML, Trower EJ, Stein NT, Lingappa UF, Naviaux J, Thorpe MT, Cantine MD, Fischer WW, Knoll AH, Grotzinger JP. Non-lithifying microbial ecosystem dissolves peritidal lime sand. Nat Commun 2021; 12:3037. [PMID: 34031392 PMCID: PMC8144198 DOI: 10.1038/s41467-021-23006-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 04/07/2021] [Indexed: 11/26/2022] Open
Abstract
Microbialites accrete where environmental conditions and microbial metabolisms promote lithification, commonly through carbonate cementation. On Little Ambergris Cay, Turks and Caicos Islands, microbial mats occur widely in peritidal environments above ooid sand but do not become lithified or preserved. Sediment cores and porewater geochemistry indicated that aerobic respiration and sulfide oxidation inhibit lithification and dissolve calcium carbonate sand despite widespread aragonite precipitation from platform surface waters. Here, we report that in tidally pumped environments, microbial metabolisms can negate the effects of taphonomically-favorable seawater chemistry on carbonate mineral saturation and microbialite development. Present et al. examine the processes controlling lithification of microbial mats in a Caribbean peritidal carbonate environment. The authors present sedimentological and geochemical evidence of a surprising bias against preserving the most robust, widespread microbial ecosystems in the sedimentary record.
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Affiliation(s)
- Theodore M Present
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA.
| | - Maya L Gomes
- Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - Elizabeth J Trower
- Department of Geological Sciences, University of Colorado Boulder, Boulder, CO, USA
| | - Nathan T Stein
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA
| | - Usha F Lingappa
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA
| | - John Naviaux
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA
| | - Michael T Thorpe
- NASA Postdoctoral Program, NASA Johnson Space Center, Houston, TX, USA
| | - Marjorie D Cantine
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Woodward W Fischer
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA
| | - Andrew H Knoll
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA
| | - John P Grotzinger
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA
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15
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Molina V, Eissler Y, Fernandez C, Cornejo-D'Ottone M, Dorador C, Bebout BM, Jeffrey WH, Romero C, Hengst M. Greenhouse gases and biogeochemical diel fluctuations in a high-altitude wetland. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 768:144370. [PMID: 33454466 DOI: 10.1016/j.scitotenv.2020.144370] [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: 09/09/2020] [Revised: 12/02/2020] [Accepted: 12/04/2020] [Indexed: 06/12/2023]
Abstract
The landscapes of high-altitude wetland ecosystems are characterized by different kinds of aquatic sites, including ponds holding conspicuous microbial life. Here, we examined a representative pond of the wetland landscape for dynamics of greenhouse gases, and their association with other relevant biogeochemical conditions including diel shifts of microbial communities' structure and activity over two consecutive days. Satellite image analysis indicates that the area of ponds cover 238 of 381.3 Ha (i.e., 62.4%), representing a significant landscape in this wetland. Solar radiation, wind velocity and temperature varied daily and between the days sampled, influencing the biogeochemical dynamics in the pond, shifting the pond reservoir of inorganic versus dissolved organic nitrogen/phosphorus bioavailability, between day 1 and day 2. Day 2 was characterized by high dissolved organic nitrogen/phosphorus and N2O accumulation. CH4 presented a positive excess showing maxima at hours of high radiation during both days. The microbial community in the sediment was diverse and enriched in keystone active groups potentially related with GHG recycling including bacteria and archaea, such as Cyanobacteria, Verrucomicrobia, Rhodobacterales and Nanoarchaeaota (Woesearchaeia). Archaea account for the microbial community composition changes between both days and for the secondary productivity in the water measured during day 2. The results indicate that an intense recycling of organic matter occurs in the pond systems and that the activity of the microbial community is correlated with the availability of nutrients. Together, the above results indicate a net sink of CO2 and N2O, which has also been reported for other natural and artificial ponds. Overall, our two-day fluctuation study in a representative pond of a high-altitude wetland aquatic landscape indicates the need to explore in more detail the short-term besides the long-term biogeochemical variability in arid ecosystems of the Andes plateau, where wetlands are hotspots of life currently under high anthropogenic pressure.
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Affiliation(s)
- Verónica Molina
- Departamento de Biología, Observatorio de Ecología Microbiana, Facultad de Ciencias Naturales y Exactas, Universidad de Playa Ancha, Avenida Leopoldo Carvallo 270, Playa Ancha, Valparaíso 2340000, Chile; HUB Ambiental UPLA, Universidad de Playa Ancha, Avenida Leopoldo Carvallo 200, Playa Ancha, Valparaíso 2340000, Chile.
| | - Yoanna Eissler
- Instituto de Química y Bioquímica, Facultad de Ciencias, Universidad de Valparaíso, Gran Bretaña 1111, Playa Ancha, Valparaíso 2360102, Chile.
| | - Camila Fernandez
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire d'Océanographie Microbienne (LOMIC), Observatoire Océanologique, de Banyuls sur Mer, F-6665 Banyuls/mer, France; Interdisciplinary Center for Aquaculture Research (INCAR), PIA CONICYT COPAS SUR-AUSTRAL Program, Barrio Universitario s/n, Universidad de Concepción, Concepción 4030000, Chile; Centro Fondap IDEAL, Universidad Austral de Chile, Independencia 631, Valdivia 5110566, Chile.
| | - Marcela Cornejo-D'Ottone
- Escuela de Ciencias del Mar e Instituto Milenio de Oceanografía, Pontificia Universidad Católica de Valparaíso, Altamirano 1480, Valparaíso 2360007, Chile.
| | - Cristina Dorador
- Laboratorio de Complejidad Microbiana y Ecología Funcional, Instituto de Antofagasta, Departamento de Biotecnología, Facultad de Ciencias del Mar y Recursos Biológicos, Universidad de Antofagasta, Avenida Universidad de Antofagasta s/n, Antofagasta 1240000, Chile; Centre for Biotechnology and Bioengineering, Santiago 8320000, Chile.
| | - Brad M Bebout
- Exobiology Branch, Ames Research Center National Aeronautics and Space Administration, Moffett Field, CA 94035-0001, USA.
| | - Wade H Jeffrey
- Center for Environmental Diagnostics and Bioremediation, University of West Florida, Pensacola, FL 32514, USA.
| | - Carlos Romero
- Laboratorio de Teledetección Ambiental, Departamento de Ciencias Geográficas, Facultad de Ciencias Naturales y Exactas, Universidad de Playa Ancha. Avenida Leopoldo Carvallo 270, Playa Ancha, Valparaíso 2340000, Chile.
| | - Martha Hengst
- Centre for Biotechnology and Bioengineering, Santiago 8320000, Chile; Departamento de Ciencias Farmacéuticas, Facultad de Ciencias, Universidad Católica del Norte. Av Angamos 0610, Antofagasta 1270709, Chile.
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16
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Bolay P, Rozbeh R, Muro-Pastor MI, Timm S, Hagemann M, Florencio FJ, Forchhammer K, Klähn S. The Novel P II-Interacting Protein PirA Controls Flux into the Cyanobacterial Ornithine-Ammonia Cycle. mBio 2021; 12:e00229-21. [PMID: 33758091 PMCID: PMC8092223 DOI: 10.1128/mbio.00229-21] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 02/16/2021] [Indexed: 12/11/2022] Open
Abstract
Among prokaryotes, cyanobacteria have an exclusive position as they perform oxygenic photosynthesis. Cyanobacteria substantially differ from other bacteria in further aspects, e.g., they evolved a plethora of unique regulatory mechanisms to control primary metabolism. This is exemplified by the regulation of glutamine synthetase (GS) via small proteins termed inactivating factors (IFs). Here, we reveal another small protein, encoded by the ssr0692 gene in the model strain Synechocystis sp. PCC 6803, that regulates flux into the ornithine-ammonia cycle (OAC), the key hub of cyanobacterial nitrogen stockpiling and remobilization. This regulation is achieved by the interaction with the central carbon/nitrogen control protein PII, which commonly controls entry into the OAC by activating the key enzyme of arginine synthesis, N-acetyl-l-glutamate kinase (NAGK). In particular, the Ssr0692 protein competes with NAGK for PII binding and thereby prevents NAGK activation, which in turn lowers arginine synthesis. Accordingly, we termed it PII-interacting regulator of arginine synthesis (PirA). Similar to the GS IFs, PirA accumulates in response to ammonium upshift due to relief from repression by the global nitrogen control transcription factor NtcA. Consistent with this, the deletion of pirA affects the balance of metabolite pools of the OAC in response to ammonium shocks. Moreover, the PirA-PII interaction requires ADP and is prevented by PII mutations affecting the T-loop conformation, the major protein interaction surface of this signal processing protein. Thus, we propose that PirA is an integrator determining flux into N storage compounds not only depending on the N availability but also the energy state of the cell.IMPORTANCE Cyanobacteria contribute a significant portion to the annual oxygen yield and play important roles in biogeochemical cycles, e.g., as major primary producers. Due to their photosynthetic lifestyle, cyanobacteria also arouse interest as hosts for the sustainable production of fuel components and high-value chemicals. However, their broad application as microbial cell factories is hampered by limited knowledge about the regulation of metabolic fluxes in these organisms. Our research identified a novel regulatory protein that controls nitrogen flux, in particular arginine synthesis. Besides its role as a proteinogenic amino acid, arginine is a precursor for the cyanobacterial storage compound cyanophycin, which is of potential interest to biotechnology. Therefore, the obtained results will not only enhance our understanding of flux control in these organisms but also help to provide a scientific basis for targeted metabolic engineering and, hence, the design of photosynthesis-driven biotechnological applications.
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Affiliation(s)
- Paul Bolay
- Helmholtz Centre for Environmental Research, Department of Solar Materials, Leipzig, Germany
| | - Rokhsareh Rozbeh
- Interfaculty Institute for Microbiology and Infection Medicine, Organismic Interactions Department, Tübingen University, Tübingen, Germany
| | - M Isabel Muro-Pastor
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, Sevilla, Spain
| | - Stefan Timm
- Department of Plant Physiology, University of Rostock, Rostock, Germany
| | - Martin Hagemann
- Department of Plant Physiology, University of Rostock, Rostock, Germany
| | - Francisco J Florencio
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, Sevilla, Spain
| | - Karl Forchhammer
- Interfaculty Institute for Microbiology and Infection Medicine, Organismic Interactions Department, Tübingen University, Tübingen, Germany
| | - Stephan Klähn
- Helmholtz Centre for Environmental Research, Department of Solar Materials, Leipzig, Germany
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17
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Jahnke LL, Des Marais DJ. Carbon isotopic composition of lipid biomarkers from an endoevaporitic gypsum crust microbial mat reveals cycling of mineralized organic carbon. GEOBIOLOGY 2019; 17:643-659. [PMID: 31361088 DOI: 10.1111/gbi.12355] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 06/02/2019] [Accepted: 06/23/2019] [Indexed: 06/10/2023]
Abstract
Microbial mats that inhabit gypsum deposits in ponds at Guerrero Negro, Baja California Sur, Mexico, developed distinct pigmented horizons that provided an opportunity to examine the fixation and flow of carbon through a trophic structure and, in conjunction with previous phylogenetic analyses, to assess the diagenetic fates of molecular δ13 C biosignatures. The δ13 C values of individual biomarker lipids, total carbon, and total organic carbon (TOC) were determined for each of the following horizons: tan-orange (TO) at the surface, green (G), purple (P), and olive-black (OB) at the bottom. δ13 C of individual fatty acids from intact polar lipids (IPFA) in TO were similar to δ13 C of dissolved inorganic carbon (DIC) in the overlying water column, indicating limited discrimination by cyanobacteria during CO2 fixation. δ13 CTOC of the underlying G was 3‰ greater than that of TO. The most δ13 C-depleted acetogenic lipids in the upper horizons were the cyanobacterial biomarkers C17 n-alkanes and polyunsaturated fatty acids. Bishomohopanol was 4 to 7‰ enriched, relative to alkanes and intact polar fatty acids (IPFA), respectively. Acyclic C20 isoprenoids were depleted by 14‰ relative to bishomohopanol. Significantly, ∆[δ13 CTOC - δ13 C∑IPFA ] increased from 6.9‰ in TO to 14.7‰ in OB. This major trend might indicate that 13 C-enriched residual organic matter accumulated at depth. The permanently anoxic P horizon was dominated by anoxygenic phototrophs and sulfate-reducing bacteria. P hosted an active sulfur-dependent microbial community. IPFA and bishomohopanol were 13 C-depleted relative to upper crust by 7 and 4‰, respectively, and C20 isoprenoids were somewhat 13 C-enriched. Synthesis of alkanes in P was evidenced only by 13 C-depleted n-octadecane and 8-methylhexadecane. In OB, the marked increase of total inorganic carbon δ13 C (δ13 CTIC ) of >6‰ perhaps indicated terminal mineralization. This δ13 CTIC increase is consistent with degradation of the osmolyte glycine betaine by methylotrophic methanogens and loss of 13 C-depleted methane from the mat.
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Affiliation(s)
- Linda L Jahnke
- Exobiology Branch, Space Science & Astrobiology Division, NASA-Ames Research Center, Moffett Field, CA, USA
| | - David J Des Marais
- Exobiology Branch, Space Science & Astrobiology Division, NASA-Ames Research Center, Moffett Field, CA, USA
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18
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Finke N, Simister RL, O'Neil AH, Nomosatryo S, Henny C, MacLean LC, Canfield DE, Konhauser K, Lalonde SV, Fowle DA, Crowe SA. Mesophilic microorganisms build terrestrial mats analogous to Precambrian microbial jungles. Nat Commun 2019; 10:4323. [PMID: 31541087 PMCID: PMC6754388 DOI: 10.1038/s41467-019-11541-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 07/03/2019] [Indexed: 12/02/2022] Open
Abstract
Development of Archean paleosols and patterns of Precambrian rock weathering suggest colonization of continents by subaerial microbial mats long before evolution of land plants in the Phanerozoic Eon. Modern analogues for such mats, however, have not been reported, and possible biogeochemical roles of these mats in the past remain largely conceptual. We show that photosynthetic, subaerial microbial mats from Indonesia grow on mafic bedrocks at ambient temperatures and form distinct layers with features similar to Precambrian mats and paleosols. Such subaerial mats could have supported a substantial aerobic biosphere, including nitrification and methanotrophy, and promoted methane emissions and oxidative weathering under ostensibly anoxic Precambrian atmospheres. High C-turnover rates and cell abundances would have made these mats prime locations for early microbial diversification. Growth of landmass in the late Archean to early Proterozoic Eons could have reorganized biogeochemical cycles between land and sea impacting atmospheric chemistry and climate.
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Affiliation(s)
- N Finke
- Departments of Microbiology and Immunology and Earth, Ocean, and Atmospheric Sciences, University of British Columbia, Vancouver, Canada
- Nordic center for earth evolution (NordCEE), University of Southern Denmark, Odense, Denmark
| | - R L Simister
- Departments of Microbiology and Immunology and Earth, Ocean, and Atmospheric Sciences, University of British Columbia, Vancouver, Canada
| | | | - S Nomosatryo
- Research center for Limnology, Indonesian Institute of Sciences (LIPI), Jawa Barat, Indonesia
- GFZ German Research Centre for Geosciences, Potsdam, Germany
| | - C Henny
- Research center for Limnology, Indonesian Institute of Sciences (LIPI), Jawa Barat, Indonesia
| | | | - D E Canfield
- Nordic center for earth evolution (NordCEE), University of Southern Denmark, Odense, Denmark
| | - K Konhauser
- Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Canada
| | - S V Lalonde
- European Institute for Marine Studies, Technopôle Brest-Iroise, Plouzané, France
| | - D A Fowle
- Department of Geology, University of Kansas, Lawrence, KS, USA
| | - S A Crowe
- Departments of Microbiology and Immunology and Earth, Ocean, and Atmospheric Sciences, University of British Columbia, Vancouver, Canada.
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19
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Ward LM, Shih PM. The evolution and productivity of carbon fixation pathways in response to changes in oxygen concentration over geological time. Free Radic Biol Med 2019; 140:188-199. [PMID: 30790657 DOI: 10.1016/j.freeradbiomed.2019.01.049] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 01/12/2019] [Accepted: 01/31/2019] [Indexed: 12/25/2022]
Abstract
The fixation of inorganic carbon species like CO2 to more reduced organic forms is one of the most fundamental processes of life as we know it. Although several carbon fixation pathways are known to exist, on Earth today nearly all global carbon fixation is driven by the Calvin cycle in oxygenic photosynthetic plants, algae, and Cyanobacteria. At other times in Earth history, other organisms utilizing different carbon fixation pathways may have played relatively larger roles, with this balance shifting over geological time as the environmental context of life has changed and evolutionary innovations accumulated. Among the most dramatic changes that our planet and the biosphere have undergone are those surrounding the rise of O2 in our atmosphere-first during the Great Oxygenation Event at ∼2.3 Ga, and perhaps again during Neoproterozoic or Paleozoic time. These oxygenation events likely represent major step changes in the tempo and mode of biological productivity as a result of the increased productivity of oxygenic photosynthesis and the introduction of O2 into geochemical and biological systems, and likely involved shifts in the relative contribution of different carbon fixation pathways. Here, we review what is known from both the rock record and comparative biology about the evolution of carbon fixation pathways, their contributions to primary productivity through time, and their relationship to the evolving oxygenation state of the fluid Earth following the evolution and expansion of oxygenic photosynthesis.
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Affiliation(s)
- Lewis M Ward
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, United States.
| | - Patrick M Shih
- Department of Plant Biology, University of California, Davis, Davis, CA, United States; Department of Energy, Feedstocks Division, Joint BioEnergy Institute, Emeryville, CA, United States; Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States.
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20
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Efficient recycling of nutrients in modern and past hypersaline environments. Sci Rep 2019; 9:3718. [PMID: 30842491 PMCID: PMC6403304 DOI: 10.1038/s41598-019-40174-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 02/11/2019] [Indexed: 11/09/2022] Open
Abstract
The biogeochemistry of hypersaline environments is strongly influenced by changes in biological processes and physicochemical parameters. Although massive evaporation events have occurred repeatedly throughout Earth history, their biogeochemical cycles and global impact remain poorly understood. Here, we provide the first nitrogen isotopic data for nutrients and chloropigments from modern shallow hypersaline environments (solar salterns, Trapani, Italy) and apply the obtained insights to δ15N signatures of the Messinian salinity crisis (MSC) in the late Miocene. Concentrations and δ15N of chlorophyll a, bacteriochlorophyll a, nitrate, and ammonium in benthic microbial mats indicate that inhibition of nitrification suppresses denitrification and anammox, resulting in efficient ammonium recycling within the mats and high primary productivity. We also suggest that the release of 15N-depleted NH3(gas) with increasing salinity enriches ammonium 15N in surface brine (≈34.0‰). Such elevated δ15N is also recorded in geoporphyrins isolated from sediments of the MSC peak (≈20‰), reflecting ammonium supply sufficient for sustaining phototrophic primary production. We propose that efficient nutrient supply combined with frequent bottom-water anoxia and capping of organic-rich sediments by evaporites of the Mediterranean MSC could have contributed to atmospheric CO2 reduction during the late Miocene.
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21
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The Taphonomy of Proterozoic Microbial Mats and Implications for Early Diagenetic Silicification. GEOSCIENCES 2019. [DOI: 10.3390/geosciences9010040] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The complex nature of growth and decomposition in microbial mats results in a broad range of microbial preservation. Such taphonomic variability complicates both the description of microbial elements preserved within geologic materials and the potential interpretation of microbial biomarkers. This study uses a taphonomic assessment to explore the preservation of different microbial components within silicified microbial mats of the late Mesoproterozoic (~1.0 Ga) Angmaat Formation, Bylot Supergroup, Baffin Island. The Angmaat Formation consists of unmetamorphosed and essentially undeformed strata that represent intertidal to supratidal deposition within an evaporative microbial flat. Early diagenetic silicification preserved microbial communities across a range of environments, from those episodically exposed to persistently submerged. Here, we present the development of a new methodology involving the use of high-resolution image mosaics to investigate the taphonomy of microfossils preserved in these mats. A taphonomic grade is assigned using a modified classification that accounts for both the taphonomic preservation state (good, fair, poor) of individual microfossils, as well as the degree of compaction of the overall mat. We show that although various taphonomic states occur within each of the silicified mats, the overall taphonomic assessment differentiates between well-preserved mats that are interpreted to have been silicified during active growth, to highly degraded and compacted mats that are interpreted to represent preservation during later stages of biological decomposition. These data indicate that even small changes in the timing of silicification may have substantial implications on our identification of microbial biomarkers and, therefore, our interpretation of early Earth ecosystems.
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22
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DiLoreto ZA, Bontognali TRR, Al Disi ZA, Al-Kuwari HAS, Williford KH, Strohmenger CJ, Sadooni F, Palermo C, Rivers JM, McKenzie JA, Tuite M, Dittrich M. Microbial community composition and dolomite formation in the hypersaline microbial mats of the Khor Al-Adaid sabkhas, Qatar. Extremophiles 2019; 23:201-218. [PMID: 30617527 DOI: 10.1007/s00792-018-01074-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 12/29/2018] [Indexed: 11/24/2022]
Abstract
The Khor Al-Adaid sabkha in Qatar is among the rare extreme environments on Earth where it is possible to study the formation of dolomite-a carbonate mineral whose origin remains unclear and has been hypothetically linked to microbial activity. By combining geochemical measurements with microbiological analysis, we have investigated the microbial mats colonizing the intertidal areas of sabhka. The main aim of this study was to identify communities and conditions that are favorable for dolomite formation. We inspected and sampled two locations. The first site was colonized by microbial mats that graded vertically from photo-oxic to anoxic conditions and were dominated by cyanobacteria. The second site, with higher salinity, had mats with an uppermost photo-oxic layer dominated by filamentous anoxygenic photosynthetic bacteria (FAPB), which potentially act as a protective layer against salinity for cyanobacterial species within the deeper layers. Porewater in the uppermost layers of the both investigated microbial mats was supersaturated with respect to dolomite. Corresponding to the variation of the microbial community's vertical structure, a difference in crystallinity and morphology of dolomitic phases was observed: dumbbell-shaped proto-dolomite in the mats dominated by cyanobacteria and rhombohedral ordered-dolomite in the mat dominated by FAPB.
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Affiliation(s)
- Zach A DiLoreto
- Department of Physical & Environmental Sciences, University of Toronto Scarborough, 1065 Military Trail, Toronto, ON, M1C 1A4, Canada
| | - Tomaso R R Bontognali
- Department of Earth Sciences, ETH Zurich, Zurich, Switzerland
- Qatar University, Doha, Qatar
- Space Exploration Institute, Neuchatel, Switzerland
| | | | | | - Kenneth H Williford
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | | | | | - Christine Palermo
- Department of Physical & Environmental Sciences, University of Toronto Scarborough, 1065 Military Trail, Toronto, ON, M1C 1A4, Canada
| | | | | | - Michael Tuite
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Maria Dittrich
- Department of Physical & Environmental Sciences, University of Toronto Scarborough, 1065 Military Trail, Toronto, ON, M1C 1A4, Canada.
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23
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Lee JZ, Everroad RC, Karaoz U, Detweiler AM, Pett-Ridge J, Weber PK, Prufert-Bebout L, Bebout BM. Metagenomics reveals niche partitioning within the phototrophic zone of a microbial mat. PLoS One 2018; 13:e0202792. [PMID: 30204767 PMCID: PMC6133358 DOI: 10.1371/journal.pone.0202792] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Accepted: 08/09/2018] [Indexed: 11/19/2022] Open
Abstract
Hypersaline photosynthetic microbial mats are stratified microbial communities known for their taxonomic and metabolic diversity and strong light-driven day-night environmental gradients. In this study of the upper photosynthetic zone of hypersaline microbial mats of Elkhorn Slough, California (USA), we show how metagenome sequencing can be used to meaningfully assess microbial ecology and genetic partitioning in these complex microbial systems. Mapping of metagenome reads to the dominant Cyanobacteria observed in the system, Coleofasciculus (Microcoleus) chthonoplastes, was used to examine strain variants within these metagenomes. Highly conserved gene subsystems indicated a core genome for the species, and a number of variant genes and subsystems suggested strain level differentiation, especially for nutrient utilization and stress response. Metagenome sequence coverage binning was used to assess ecosystem partitioning of remaining microbes to both reconstruct the model organisms in silico and identify their ecosystem functions as well as to identify novel clades and propose their role in the biogeochemical cycling of mats. Functional gene annotation of these bins (primarily of Proteobacteria, Bacteroidetes, and Cyanobacteria) recapitulated the known biogeochemical functions in microbial mats using a genetic basis, and revealed significant diversity in the Bacteroidetes, presumably in heterotrophic cycling. This analysis also revealed evidence of putative phototrophs within the Gemmatimonadetes and Gammaproteobacteria residing in microbial mats. This study shows that metagenomic analysis can produce insights into the systems biology of microbial ecosystems from a genetic perspective and to suggest further studies of novel microbes.
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Affiliation(s)
- Jackson Z. Lee
- Exobiology Branch, NASA Ames Research Center, Moffett Field, CA, United States of America
- Bay Area Environmental Research Institute, Petaluma, CA, United States of America
- * E-mail:
| | - R. Craig Everroad
- Exobiology Branch, NASA Ames Research Center, Moffett Field, CA, United States of America
| | - Ulas Karaoz
- Earth and Environmental Sciences, Lawrence Berkeley National Laboratory, Berkeley, CA, United States of America
| | - Angela M. Detweiler
- Exobiology Branch, NASA Ames Research Center, Moffett Field, CA, United States of America
- Bay Area Environmental Research Institute, Petaluma, CA, United States of America
| | - Jennifer Pett-Ridge
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, United States of America
| | - Peter K. Weber
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, United States of America
| | - Leslie Prufert-Bebout
- Exobiology Branch, NASA Ames Research Center, Moffett Field, CA, United States of America
| | - Brad M. Bebout
- Exobiology Branch, NASA Ames Research Center, Moffett Field, CA, United States of America
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Shen Y, Thiel V, Duda JP, Reitner J. Tracing the fate of steroids through a hypersaline microbial mat (Kiritimati, Kiribati/Central Pacific). GEOBIOLOGY 2018; 16:307-318. [PMID: 29577559 DOI: 10.1111/gbi.12279] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 01/29/2018] [Indexed: 06/08/2023]
Abstract
Eukaryotic steranes are typically absent or occur in very low concentrations in Precambrian sedimentary rocks. However, it is as yet unclear whether this may reflect low source inputs or a preservational bias. For instance, it has been proposed that eukaryotic lipids were profoundly degraded in benthic microbial mats that were ubiquitous prior to the advent of vertical bioturbation in the Cambrian ("mat-seal effect"). It is therefore important to test the microbial turnover and degradation of eukaryotic steroids in real-world microbial mats. Here we assessed steroid inventories in different layers of a microbial mat from a hypersaline lake on Kiritimati (Central Pacific). Various eukaryote-derived C27 -C30 steroids were detected in all mat layers. These compounds most likely entered the mat system as unsaturated sterols from the water column or the topmost mat, and were progressively altered during burial in the deeper, anoxic mat layers over c. 103 years. This is reflected by increasing proportions of saturated sterols and sterenes, as well as the presence of thiosteranes in certain horizons. Sterol alteration can partly be assigned to microbial transformation but is also due to chemical reactions promoted by the reducing environment in the deeper mat layers. Notably, however, compounds with a sterane skeleton were similarly abundant in all mat layers and their absolute concentrations did not show any systematic decrease. The observed decrease of steroid/hopanoid ratios with depth may thus rather indicate a progressive "dilution" by lipids derived from heterotrophic bacteria. Further, pyrolysis revealed that steroids, in contrast to hopanoids, were not sequestered into non-extractable organic matter. This may lead to a preservational bias against steroids during later stages of burial. Taken together, steroid preservation in the microbial mat is not only controlled by heterotrophic degradation, but rather reflects a complex interplay of taphonomic processes.
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Affiliation(s)
- Y Shen
- Department of Geobiology, Geoscience Centre, Georg-August-Universität Göttingen, Göttingen, Germany
| | - V Thiel
- Department of Geobiology, Geoscience Centre, Georg-August-Universität Göttingen, Göttingen, Germany
| | - J-P Duda
- Department of Geobiology, Geoscience Centre, Georg-August-Universität Göttingen, Göttingen, Germany
- 'Origin of Life' Group, Göttingen Academy of Sciences and Humanities, Göttingen, Germany
| | - J Reitner
- Department of Geobiology, Geoscience Centre, Georg-August-Universität Göttingen, Göttingen, Germany
- 'Origin of Life' Group, Göttingen Academy of Sciences and Humanities, Göttingen, Germany
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Gomes ML, Fike DA, Bergmann KD, Jones C, Knoll AH. Environmental insights from high-resolution (SIMS) sulfur isotope analyses of sulfides in Proterozoic microbialites with diverse mat textures. GEOBIOLOGY 2018; 16:17-34. [PMID: 29047210 DOI: 10.1111/gbi.12265] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 09/01/2017] [Indexed: 06/07/2023]
Abstract
In modern microbial mats, hydrogen sulfide shows pronounced sulfur isotope (δ34 S) variability over small spatial scales (~50‰ over <4 mm), providing information about microbial sulfur cycling within different ecological niches in the mat. In the geological record, the location of pyrite formation, overprinting from mat accretion, and post-depositional alteration also affect both fine-scale δ34 S patterns and bulk δ34 Spyrite values. We report μm-scale δ34 S patterns in Proterozoic samples with well-preserved microbial mat textures. We show a well-defined relationship between δ34 S values and sulfide mineral grain size and type. Small pyrite grains (<25 μm) span a large range, tending toward high δ34 S values (-54.5‰ to 11.7‰, mean: -14.4‰). Larger pyrite grains (>25 μm) have low but equally variable δ34 S values (-61.0‰ to -10.5‰, mean: -44.4‰). In one sample, larger sphalerite grains (>35 μm) have intermediate and essentially invariant δ34 S values (-22.6‰ to -15.6‰, mean: -19.4‰). We suggest that different sulfide mineral populations reflect separate stages of formation. In the first stage, small pyrite grains form near the mat surface along a redox boundary where high rates of sulfate reduction, partial closed-system sulfate consumption in microenvironments, and/or sulfide oxidation lead to high δ34 S values. In another stage, large sphalerite grains with low δ34 S values grow along the edges of pore spaces formed from desiccation of the mat. Large pyrite grains form deeper in the mat at slower sulfate reduction rates, leading to low δ34 Ssulfide values. We do not see evidence for significant 34 S-enrichment in bulk pore water sulfide at depth in the mat due to closed-system Rayleigh fractionation effects. On a local scale, Rayleigh fractionation influences the range of δ34 S values measured for individual pyrite grains. Fine-scale analyses of δ34 Spyrite patterns can thus be used to extract environmental information from ancient microbial mats and aid in the interpretation of bulk δ34 Spyrite records.
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Affiliation(s)
- M L Gomes
- Washington University, Saint Louis, MO, USA
- Harvard University, Cambridge, MA, USA
| | - D A Fike
- Washington University, Saint Louis, MO, USA
| | - K D Bergmann
- Massachusettes Institute of Technology, Cambridge, MA, USA
| | - C Jones
- Washington University, Saint Louis, MO, USA
| | - A H Knoll
- Harvard University, Cambridge, MA, USA
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Ecological interactions in Cloudina from the Ediacaran of Brazil: implications for the rise of animal biomineralization. Sci Rep 2017; 7:5482. [PMID: 28710440 PMCID: PMC5511220 DOI: 10.1038/s41598-017-05753-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 06/05/2017] [Indexed: 11/23/2022] Open
Abstract
At the Ediacaran/Cambrian boundary, ecosystems witnessed an unparalleled biological innovation: the appearance of shelled animals. Here, we report new paleoecological and paleobiological data on Cloudina, which was one of the most abundant shelled animals at the end of the Ediacaran. We report the close association of Cloudina tubes with microbial mat textures as well as organic-rich material, syndepositional calcite and goethite cement between their flanges, thus reinforcing the awareness of metazoan/microorganism interactions at the end of the Ediacaran. The preservation of in situ tubes suggests a great plasticity of substrate utilization, with evidence of different life modes and avoidance behavior. Geochemical analysis revealed walls composed of two secondary laminae and organic sheets. Some walls presented boreholes that are here described as predation marks. Taken together, these data add further information regarding the structuring of shelled animal communities in marine ecosystems.
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Louyakis AS, Mobberley JM, Vitek BE, Visscher PT, Hagan PD, Reid RP, Kozdon R, Orland IJ, Valley JW, Planavsky NJ, Casaburi G, Foster JS. A Study of the Microbial Spatial Heterogeneity of Bahamian Thrombolites Using Molecular, Biochemical, and Stable Isotope Analyses. ASTROBIOLOGY 2017; 17:413-430. [PMID: 28520472 PMCID: PMC5767104 DOI: 10.1089/ast.2016.1563] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Thrombolites are buildups of carbonate that exhibit a clotted internal structure formed through the interactions of microbial mats and their environment. Despite recent advances, we are only beginning to understand the microbial and molecular processes associated with their formation. In this study, a spatial profile of the microbial and metabolic diversity of thrombolite-forming mats of Highborne Cay, The Bahamas, was generated by using 16S rRNA gene sequencing and predictive metagenomic analyses. These molecular-based approaches were complemented with microelectrode profiling and in situ stable isotope analysis to examine the dominant taxa and metabolic activities within the thrombolite-forming communities. Analyses revealed three distinctive zones within the thrombolite-forming mats that exhibited stratified populations of bacteria and archaea. Predictive metagenomics also revealed vertical profiles of metabolic capabilities, such as photosynthesis and carboxylic and fatty acid synthesis within the mats that had not been previously observed. The carbonate precipitates within the thrombolite-forming mats exhibited isotopic geochemical signatures suggesting that the precipitation within the Bahamian thrombolites is photosynthetically induced. Together, this study provides the first look at the spatial organization of the microbial populations within Bahamian thrombolites and enables the distribution of microbes to be correlated with their activities within modern thrombolite systems. Key Words: Thrombolites-Microbial diversity-Metagenome-Stable isotopes-Microbialites. Astrobiology 17, 413-430.
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Affiliation(s)
- Artemis S. Louyakis
- Department of Microbiology and Cell Science, University of Florida, Space Life Sciences Lab, Merritt Island, Florida
| | - Jennifer M. Mobberley
- Department of Microbiology and Cell Science, University of Florida, Space Life Sciences Lab, Merritt Island, Florida
| | - Brooke E. Vitek
- Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida
| | - Pieter T. Visscher
- Department of Marine Sciences, University of Connecticut, Groton, Connecticut
| | - Paul D. Hagan
- Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida
| | - R. Pamela Reid
- Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, Florida
| | - Reinhard Kozdon
- Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York
- Department of Geoscience, University of Wisconsin, Madison, Wisconsin
| | - Ian J. Orland
- Department of Geoscience, University of Wisconsin, Madison, Wisconsin
| | - John W. Valley
- Department of Geoscience, University of Wisconsin, Madison, Wisconsin
| | - Noah J. Planavsky
- Department of Geology and Geophysics, Yale University, New Haven, Connecticut
| | - Giorgio Casaburi
- Department of Microbiology and Cell Science, University of Florida, Space Life Sciences Lab, Merritt Island, Florida
| | - Jamie S. Foster
- Department of Microbiology and Cell Science, University of Florida, Space Life Sciences Lab, Merritt Island, Florida
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28
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Kinsman-Costello LE, Sheik CS, Sheldon ND, Allen Burton G, Costello DM, Marcus D, Uyl PAD, Dick GJ. Groundwater shapes sediment biogeochemistry and microbial diversity in a submerged Great Lake sinkhole. GEOBIOLOGY 2017; 15:225-239. [PMID: 27671809 DOI: 10.1111/gbi.12215] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 08/25/2016] [Indexed: 06/06/2023]
Abstract
For a large part of earth's history, cyanobacterial mats thrived in low-oxygen conditions, yet our understanding of their ecological functioning is limited. Extant cyanobacterial mats provide windows into the putative functioning of ancient ecosystems, and they continue to mediate biogeochemical transformations and nutrient transport across the sediment-water interface in modern ecosystems. The structure and function of benthic mats are shaped by biogeochemical processes in underlying sediments. A modern cyanobacterial mat system in a submerged sinkhole of Lake Huron (LH) provides a unique opportunity to explore such sediment-mat interactions. In the Middle Island Sinkhole (MIS), seeping groundwater establishes a low-oxygen, sulfidic environment in which a microbial mat dominated by Phormidium and Planktothrix that is capable of both anoxygenic and oxygenic photosynthesis, as well as chemosynthesis, thrives. We explored the coupled microbial community composition and biogeochemical functioning of organic-rich, sulfidic sediments underlying the surface mat. Microbial communities were diverse and vertically stratified to 12 cm sediment depth. In contrast to previous studies, which used low-throughput or shotgun metagenomic approaches, our high-throughput 16S rRNA gene sequencing approach revealed extensive diversity. This diversity was present within microbial groups, including putative sulfate-reducing taxa of Deltaproteobacteria, some of which exhibited differential abundance patterns in the mats and with depth in the underlying sediments. The biological and geochemical conditions in the MIS were distinctly different from those in typical LH sediments of comparable depth. We found evidence for active cycling of sulfur, methane, and nutrients leading to high concentrations of sulfide, ammonium, and phosphorus in sediments underlying cyanobacterial mats. Indicators of nutrient availability were significantly related to MIS microbial community composition, while LH communities were also shaped by indicators of subsurface groundwater influence. These results show that interactions between the mats and sediments are crucial for sustaining this hot spot of biological diversity and biogeochemical cycling.
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Affiliation(s)
| | - C S Sheik
- Department of Biology, Large Lakes Observatory, University of Minnesota Duluth, Duluth, MN, USA
| | - N D Sheldon
- Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, USA
| | - G Allen Burton
- School of Natural Resources and the Environment, University of Michigan, Ann Arbor, MI, USA
| | - D M Costello
- Department of Biological Sciences, Kent State University, Kent, OH, USA
| | - D Marcus
- Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, USA
| | - P A Den Uyl
- Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, USA
| | - G J Dick
- Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, USA
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29
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Bernstein HC, Brislawn C, Renslow RS, Dana K, Morton B, Lindemann SR, Song HS, Atci E, Beyenal H, Fredrickson JK, Jansson JK, Moran JJ. Trade-offs between microbiome diversity and productivity in a stratified microbial mat. THE ISME JOURNAL 2017; 11:405-414. [PMID: 27801910 PMCID: PMC5270574 DOI: 10.1038/ismej.2016.133] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 07/26/2016] [Accepted: 08/05/2016] [Indexed: 11/08/2022]
Abstract
Productivity is a major determinant of ecosystem diversity. Microbial ecosystems are the most diverse on the planet yet very few relationships between diversity and productivity have been reported as compared with macro-ecological studies. Here we evaluated the spatial relationships of productivity and microbiome diversity in a laboratory-cultivated photosynthetic mat. The goal was to determine how spatial diversification of microorganisms drives localized carbon and energy acquisition rates. We measured sub-millimeter depth profiles of net primary productivity and gross oxygenic photosynthesis in the context of the localized microenvironment and community structure, and observed negative correlations between species richness and productivity within the energy-replete, photic zone. Variations between localized community structures were associated with distinct taxa as well as environmental profiles describing a continuum of biological niches. Spatial regions in the photic zone corresponding to high primary productivity and photosynthesis rates had relatively low-species richness and high evenness. Hence, this system exhibited negative species-productivity and species-energy relationships. These negative relationships may be indicative of stratified, light-driven microbial ecosystems that are able to be the most productive with a relatively smaller, even distributions of species that specialize within photic zones.
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Affiliation(s)
- Hans C Bernstein
- Chemical and Biological Signature Science, Pacific Northwest National Laboratory, Richland, WA, USA
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, USA
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, USA
| | - Colin Brislawn
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, USA
| | - Ryan S Renslow
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, USA
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, USA
| | - Karl Dana
- Chemical and Biological Signature Science, Pacific Northwest National Laboratory, Richland, WA, USA
| | - Beau Morton
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, USA
| | - Stephen R Lindemann
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, USA
| | - Hyun-Seob Song
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, USA
| | - Erhan Atci
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, USA
| | - Haluk Beyenal
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, USA
| | - James K Fredrickson
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, USA
| | - Janet K Jansson
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, USA
| | - James J Moran
- Chemical and Biological Signature Science, Pacific Northwest National Laboratory, Richland, WA, USA
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Metagenomics as a preliminary screen for antimicrobial bioprospecting. Gene 2016; 594:248-258. [DOI: 10.1016/j.gene.2016.09.021] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 09/09/2016] [Accepted: 09/14/2016] [Indexed: 11/20/2022]
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Warden JG, Casaburi G, Omelon CR, Bennett PC, Breecker DO, Foster JS. Characterization of Microbial Mat Microbiomes in the Modern Thrombolite Ecosystem of Lake Clifton, Western Australia Using Shotgun Metagenomics. Front Microbiol 2016; 7:1064. [PMID: 27458453 PMCID: PMC4933708 DOI: 10.3389/fmicb.2016.01064] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 06/24/2016] [Indexed: 12/02/2022] Open
Abstract
Microbialite-forming communities interact with the environment and influence the precipitation of calcium carbonate through their metabolic activity. The functional genes associated with these metabolic processes and their environmental interactions are therefore critical to microbialite formation. The microbiomes associated with microbialite-forming ecosystems are just now being elucidated and the extent of shared pathways and taxa across different environments is not fully known. In this study, we profiled the microbiome of microbial communities associated with lacustrine thrombolites located in Lake Clifton, Western Australia using metagenomic sequencing and compared it to the non-lithifying mats associated with surrounding sediments to determine whether differences in the mat microbiomes, particularly with respect to metabolic pathways and environmental interactions, may potentially contribute to thrombolite formation. Additionally, we used stable isotope biosignatures to delineate the dominant metabolism associated with calcium carbonate precipitation in the thrombolite build-ups. Results indicated that the microbial community associated with the Lake Clifton thrombolites was predominantly bacterial (98.4%) with Proteobacteria, Cyanobacteria, Bacteroidetes, and Actinobacteria comprising the majority of annotated reads. Thrombolite-associated mats were enriched in photoautotrophic taxa and functional genes associated with photosynthesis. Observed δ13C values of thrombolite CaCO3 were enriched by at least 3.5‰ compared to theoretical values in equilibrium with lake water DIC, which is consistent with the occurrence of photoautotrophic activity in thrombolite-associated microbial mats. In contrast, the microbiomes of microbial communities found on the sandy non-lithifying sediments of Lake Clifton represented distinct microbial communities that varied in taxa and functional capability and were enriched in heterotrophic taxa compared to the thrombolite-associated mats. This study provides new insight into the taxa and functional capabilities that differentiate potentially lithifying mats from other non-lithifying types and suggests that thrombolites are actively accreting and growing in limited areas of Lake Clifton.
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Affiliation(s)
- John G Warden
- Department of Geological Sciences, University of Texas at Austin, AustinTX, USA; Space Life Science Lab, Department of Microbiology and Cell Science, University of Florida, Merritt IslandFL, USA
| | - Giorgio Casaburi
- Space Life Science Lab, Department of Microbiology and Cell Science, University of Florida, Merritt Island FL, USA
| | - Christopher R Omelon
- Department of Geological Sciences, University of Texas at Austin, Austin TX, USA
| | - Philip C Bennett
- Department of Geological Sciences, University of Texas at Austin, Austin TX, USA
| | - Daniel O Breecker
- Department of Geological Sciences, University of Texas at Austin, Austin TX, USA
| | - Jamie S Foster
- Space Life Science Lab, Department of Microbiology and Cell Science, University of Florida, Merritt Island FL, USA
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Oxidation of Molecular Hydrogen by a Chemolithoautotrophic Beggiatoa Strain. Appl Environ Microbiol 2016; 82:2527-36. [PMID: 26896131 PMCID: PMC4959497 DOI: 10.1128/aem.03818-15] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 02/10/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED A chemolithoautotrophic strain of the family Beggiatoaceae, Beggiatoa sp. strain 35Flor, was found to oxidize molecular hydrogen when grown in a medium with diffusional gradients of oxygen, sulfide, and hydrogen. Microsensor profiles and rate measurements suggested that the strain oxidized hydrogen aerobically when oxygen was available, while hydrogen consumption under anoxic conditions was presumably driven by sulfur respiration.Beggiatoa sp. 35Flor reached significantly higher biomass in hydrogen-supplemented oxygen-sulfide gradient media, but hydrogen did not support growth of the strain in the absence of reduced sulfur compounds. Nevertheless, hydrogen oxidation can provide Beggiatoa sp. 35Flor with energy for maintenance and assimilatory purposes and may support the disposal of internally stored sulfur to prevent physical damage resulting from excessive sulfur accumulation. Our knowledge about the exposure of natural populations of Beggiatoa ceae to hydrogen is very limited, but significant amounts of hydrogen could be provided by nitrogen fixation, fermentation, and geochemical processes in several of their typical habitats such as photosynthetic microbial mats and submarine sites of hydrothermal fluid flow. IMPORTANCE Reduced sulfur compounds are certainly the main electron donors for chemolithoautotrophic Beggiatoa ceae, but the traditional focus on this topic has left other possible inorganic electron donors largely unexplored. In this paper, we provide evidence that hydrogen oxidation has the potential to strengthen the ecophysiological plasticity of Beggiatoa ceaein several ways. Moreover, we show that hydrogen oxidation by members of this family can significantly influence biogeochemical gradients and therefore should be considered in environmental studies.
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Sato Y, Civiello M, Bell SC, Willis BL, Bourne DG. Integrated approach to understanding the onset and pathogenesis of black band disease in corals. Environ Microbiol 2016; 18:752-65. [PMID: 26549807 DOI: 10.1111/1462-2920.13122] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Revised: 10/27/2015] [Accepted: 11/02/2015] [Indexed: 10/22/2022]
Abstract
Emerging infectious diseases are contributing to global declines in coral reef ecosystems, highlighting a growing need for aetiological knowledge to develop effective management strategies. In this review, we focus on black band disease (BBD), one of the most virulent diseases and the only polymicrobial disease so far known to affect corals. A multipartite microbial consortium dominated by Cyanobacteria, but also including sulfur-cycling bacteria, other bacterial groups and members of the Archaea and Eukarya, forms a sulfide-rich anaerobic mat that migrates across the surface of coral colonies, killing the underlying tissues. The polymicrobial nature of the disease challenges classic aetiological approaches to unravelling disease causation. Here, we synthesize current knowledge on the range of pathogens forming the microbial consortium with recent studies on the transmission, biogeochemistry and environmental drivers of BBD to develop a conceptual model of BBD pathogenesis. The model illustrates how the development of BBD virulence factors is linked to a cascade of microbial community shifts and associated functional roles that progressively develop the microbial consortium from comparatively benign cyanobacterial patches to virulent BBD lesions. This review showcases how an approach that integrates multiple key aspects of the disease provides insights essential to elucidating the aetiology of BBD.
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Affiliation(s)
- Yui Sato
- Australian Institute of Marine Science, PMB 3, Townsville MC, Townsville, 4810, Australia
| | - Michael Civiello
- AIMS@JCU, James Cook University, Townsville, 4811, Australia.,ARC Centre of Excellence for Coral Reef Studies and College of Marine and Environmental Sciences, James Cook University, Townsville, 4811, Australia
| | - Sara C Bell
- Australian Institute of Marine Science, PMB 3, Townsville MC, Townsville, 4810, Australia
| | - Bette L Willis
- ARC Centre of Excellence for Coral Reef Studies and College of Marine and Environmental Sciences, James Cook University, Townsville, 4811, Australia
| | - David G Bourne
- Australian Institute of Marine Science, PMB 3, Townsville MC, Townsville, 4810, Australia
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34
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Wong HL, Ahmed-Cox A, Burns BP. Molecular Ecology of Hypersaline Microbial Mats: Current Insights and New Directions. Microorganisms 2016; 4:microorganisms4010006. [PMID: 27681900 PMCID: PMC5029511 DOI: 10.3390/microorganisms4010006] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 12/08/2015] [Accepted: 12/15/2015] [Indexed: 11/17/2022] Open
Abstract
Microbial mats are unique geobiological ecosystems that form as a result of complex communities of microorganisms interacting with each other and their physical environment. Both the microorganisms present and the network of metabolic interactions govern ecosystem function therein. These systems are often found in a range of extreme environments, and those found in elevated salinity have been particularly well studied. The purpose of this review is to briefly describe the molecular ecology of select model hypersaline mat systems (Guerrero Negro, Shark Bay, S’Avall, and Kiritimati Atoll), and any potentially modulating effects caused by salinity to community structure. In addition, we discuss several emerging issues in the field (linking function to newly discovered phyla and microbial dark matter), which illustrate the changing paradigm that is seen as technology has rapidly advanced in the study of these extreme and evolutionally significant ecosystems.
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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 2052, Australia.
| | - Aria Ahmed-Cox
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney 2052, Australia.
| | - Brendan Paul 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 2052, Australia.
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Paraneeiswaran A, Shukla SK, Kumar R, Rao TS. Reduction of [Co( iii)–EDTA] −complex by a novel process using phototrophic granules: a step towards sustainable bioremediation. RSC Adv 2016. [DOI: 10.1039/c6ra01160h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
This study shows that phototrophic granules are more efficient as compared to microbial granules or monoculture bacterial culture and are a self-sustainable system to be used in bioremediation process of environmental contaminants.
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Affiliation(s)
| | - Sudhir K. Shukla
- Water and Steam Chemistry Division
- BARC
- India
- Homi Bhabha National Institute
- Mumbai 400094
| | | | - T. Subba Rao
- Water and Steam Chemistry Division
- BARC
- India
- Homi Bhabha National Institute
- Mumbai 400094
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36
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Cyanobacterial reuse of extracellular organic carbon in microbial mats. ISME JOURNAL 2015; 10:1240-51. [PMID: 26495994 PMCID: PMC5029224 DOI: 10.1038/ismej.2015.180] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Revised: 08/21/2015] [Accepted: 09/02/2015] [Indexed: 11/09/2022]
Abstract
Cyanobacterial organic matter excretion is crucial to carbon cycling in many microbial communities, but the nature and bioavailability of this C depend on unknown physiological functions. Cyanobacteria-dominated hypersaline laminated mats are a useful model ecosystem for the study of C flow in complex communities, as they use photosynthesis to sustain a more or less closed system. Although such mats have a large C reservoir in the extracellular polymeric substances (EPSs), the production and degradation of organic carbon is not well defined. To identify extracellular processes in cyanobacterial mats, we examined mats collected from Elkhorn Slough (ES) at Monterey Bay, California, for glycosyl and protein composition of the EPS. We found a prevalence of simple glucose polysaccharides containing either α or β (1,4) linkages, indicating distinct sources of glucose with differing enzymatic accessibility. Using proteomics, we identified cyanobacterial extracellular enzymes, and also detected activities that indicate a capacity for EPS degradation. In a less complex system, we characterized the EPS of a cyanobacterial isolate from ES, ESFC-1, and found the extracellular composition of biofilms produced by this unicyanobacterial culture were similar to that of natural mats. By tracing isotopically labeled EPS into single cells of ESFC-1, we demonstrated rapid incorporation of extracellular-derived carbon. Taken together, these results indicate cyanobacteria reuse excess organic carbon, constituting a dynamic pool of extracellular resources in these mats.
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Stauffert M, Cravo-Laureau C, Duran R. Dynamic of sulphate-reducing microorganisms in petroleum-contaminated marine sediments inhabited by the polychaete Hediste diversicolor. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2015; 22:15273-15284. [PMID: 25256587 DOI: 10.1007/s11356-014-3624-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 09/16/2014] [Indexed: 06/03/2023]
Abstract
The behaviour of sulphate-reducing microbial community was investigated at the oxic-anoxic interface (0-2 cm) of marine sediments when submitted to oil and enhanced bioturbation activities by the addition of Hediste diversicolor. Although total hydrocarbon removal was not improved by the addition of H. diversicolor, terminal restriction fragment length polymorphism (T-RFLP) analyses based on dsrAB (dissimilatory sulphite reductase) genes and transcripts showed different patterns according to the presence of H. diversicolor which favoured the abundance of dsrB genes during the early stages of incubation. Complementary DNA (cDNA) dsrAB libraries revealed that in presence of H. diversicolor, most dsrAB sequences belonged to hydrocarbonoclastic Desulfobacteraceae, suggesting that sulphate-reducing microorganisms (SRMs) may play an active role in hydrocarbon biodegradation in sediments where the reworking activity is enhanced. Furthermore, the presence of dsrAB sequences related to sequences found associated to environments with high dinitrogen fixation activity suggested potential N2 fixation by SRMs in bioturbated-polluted sediments.
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Affiliation(s)
- Magalie Stauffert
- Equipe Environnement et Microbiologie, Université de Pau et des Pays de l'Adour, IPREM UMR CNRS 5254, BP 1155, 64013, Pau Cedex, France
| | - Cristiana Cravo-Laureau
- Equipe Environnement et Microbiologie, Université de Pau et des Pays de l'Adour, IPREM UMR CNRS 5254, BP 1155, 64013, Pau Cedex, France.
| | - Robert Duran
- Equipe Environnement et Microbiologie, Université de Pau et des Pays de l'Adour, IPREM UMR CNRS 5254, BP 1155, 64013, Pau Cedex, France
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Pringault O, Aube J, Bouchez O, Klopp C, Mariette J, Escudie F, Senin P, Goni-Urriza M. Contrasted effects of natural complex mixtures of PAHs and metals on oxygen cycle in a microbial mat. CHEMOSPHERE 2015; 135:189-201. [PMID: 25957138 DOI: 10.1016/j.chemosphere.2015.04.037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Revised: 03/18/2015] [Accepted: 04/14/2015] [Indexed: 06/04/2023]
Abstract
The contamination of polluted environments is often due to a complex mixture of pollutants sometimes at trace levels which nevertheless may have significant effects on the diversity and functioning of organisms. The aim of this study was to assess the functional responses of a microbial mat exposed to a natural complex mixture of PAHs and metals as a function of the maturation stage of the biofilm. Microbial mats sampled in a slightly polluted environment were exposed to contaminated water of a retention basin of an oil refinery. The responses of the microbial mats differed according to season. In spring 2012, strong inhibition of both oxygen production and respiration was observed relative to the control, with rates representing less than 5% of the control after 72 h of incubation. A decrease of microbial activities was followed by a decrease of the coupling between autotrophs and heterotrophs. In contrast, in autumn 2012, no significant changes for oxygen production and respiration were observed and the coupling between autotrophs and heterotrophs was not altered. The differences observed between the spring and autumn mats might be explained by the maturity of the microbial mat with dominance of heterotrophic bacteria in spring, and diatoms and cyanobacteria in autumn, as well as by the differences in the chemical composition of the complex mixture of PAHs and metals.
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Affiliation(s)
- Olivier Pringault
- UMR 9190 MARBEC IRD-Ifremer-CNRS-Université de Montpellier, Place Eugène Bataillon, case 093, 34095 Montpellier cedex 5, France
| | - Johanne Aube
- Equipe Environnement et Microbiologie, UMR IPREM 5254, IBEAS BP 1155, Université de Pau et des Pays de l'Adour, 64013 Pau cedex, France
| | - Olivier Bouchez
- Plateforme Génomique Campus INRA, 24 chemin de borde rouge, 31326 Castanet-Tolosan Cedex, France
| | - Christophe Klopp
- Plateforme Génomique Campus INRA, 24 chemin de borde rouge, 31326 Castanet-Tolosan Cedex, France
| | - Jérome Mariette
- Plateforme Génomique Campus INRA, 24 chemin de borde rouge, 31326 Castanet-Tolosan Cedex, France
| | - Frédéric Escudie
- Plateforme Génomique Campus INRA, 24 chemin de borde rouge, 31326 Castanet-Tolosan Cedex, France
| | - Pavel Senin
- Plateforme Génomique Campus INRA, 24 chemin de borde rouge, 31326 Castanet-Tolosan Cedex, France
| | - Marisol Goni-Urriza
- Equipe Environnement et Microbiologie, UMR IPREM 5254, IBEAS BP 1155, Université de Pau et des Pays de l'Adour, 64013 Pau cedex, France
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Martins MVA, Mane MÂ, Frontalini F, Santos JF, da Silva FS, Terroso D, Miranda P, Figueira R, Laut LLM, Bernardes C, Filho JGM, Coccioni R, Dias JMA, Rocha F. Early diagenesis and clay mineral adsorption as driving factors of metal pollution in sediments: the case of Aveiro Lagoon (Portugal). ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2015; 22:10019-10033. [PMID: 25666475 DOI: 10.1007/s11356-015-4185-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 01/29/2015] [Indexed: 06/04/2023]
Abstract
This work aims to define the factors driving the accumulation of metals in the sediment of the lagoon of Aveiro (Portugal). The role of initial diagenetic processes in controlling trace metal retention in surface sediment is traced by mineralogy, magnetic susceptibility and geochemical analyses. Although several studies have focused on the metal distribution in this polihaline and anthropized coastal lagoon, most of them have been solely focused on the total metal concentrations. This study instead represents the first attempt to evaluate in a vast area of the Aveiro Lagoon the role of biogeochemical processes in metal availability and distribution in three extracted phases: exchangeable cations adsorbed by clay and elements co-precipitated with carbonates (S1), organic matter (S2) and amorphous Mn hydroxides (S3). According to the sediment guideline values, the sediment is polluted by, for instance, As and Hg in the inner area of the Murtosa Channel, Pb in the Espinheiro Channel, Aveiro City canals and Aveiro Harbour, and Zn in the northern area of the Ovar Channel. These sites are located near the source areas of pollutants and have the highest total available concentrations in each extracted phase. The total available concentrations of all toxic metals are however associated, firstly, with the production of amorphous Mn hydroxides in most of the areas and, secondly, with adsorption by organic compounds. The interplay of the different processes implies that not all of the sites near pollution sources have polluted surface sediment. The accumulation of metals depends on not only the pollution source but also the changing in the redox state of the sediments that may cause alterations in the sediment retention or releasing of redox-sensitive metals. Results of this work suggest that the biogeochemical processes may play a significant role in the increase of the pollutants in the sediment of the Aveiro Lagoon.
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Affiliation(s)
- Maria Virgínia Alves Martins
- Universidade do Estado do Rio de Janeiro, Faculdade de Geologia, Av. São Francisco Xavier, 524, Maracanã, 20550-013, Rio de Janeiro, RJ, Brazil,
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Hoffmann D, Maldonado J, Wojciechowski MF, Garcia-Pichel F. Hydrogen export from intertidal cyanobacterial mats: sources, fluxes and the influence of community composition. Environ Microbiol 2015; 17:3738-53. [DOI: 10.1111/1462-2920.12769] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 12/23/2014] [Indexed: 11/28/2022]
Affiliation(s)
- Dörte Hoffmann
- School of Life Sciences; Arizona State University; Tempe AZ 85287-4501 USA
| | - Juan Maldonado
- School of Life Sciences; Arizona State University; Tempe AZ 85287-4501 USA
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41
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Moran JJ, Doll CG, Bernstein HC, Renslow RS, Cory AB, Hutchison JR, Lindemann SR, Fredrickson JK. Spatially tracking (13) C-labelled substrate (bicarbonate) accumulation in microbial communities using laser ablation isotope ratio mass spectrometry. ENVIRONMENTAL MICROBIOLOGY REPORTS 2014; 6:786-791. [PMID: 25155264 DOI: 10.1111/1758-2229.12211] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Accepted: 08/05/2014] [Indexed: 06/03/2023]
Abstract
Microbial mats are characterized by extensive metabolic interactions, rapidly changing internal geochemical gradients, and prevalent microenvironments within tightly constrained physical structures. We present laser ablation isotope ratio mass spectrometry (LA-IRMS) as a culture-independent, spatially specific technology for tracking the accumulation of (13) C-labelled substrate into heterogeneous microbial mat communities. This study demonstrates the novel LA-IRMS approach by tracking labeled bicarbonate incorporation into a cyanobacteria-dominated microbial mat system. The spatial resolution of 50 μm was sufficient for distinguishing different mat strata and the approach effectively identified regions of greatest label incorporation. Sample preparation for LA-IRMS is straightforward and the spatial selectivity of LA-IRMS minimizes the volume of mat consumed, leaving material for complimentary analyses. We present analysis of DNA extracted from a sample post-ablation and suggest pigments, lipids or other biomarkers could similarly be extracted following ablation. LA-IRMS is well positioned to spatially resolve the accumulation of any (13) C-labelled substrate provided to a mat, making this a versatile tool for studying carbon transfer and interspecies exchanges within the limited spatial confines of such systems.
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Affiliation(s)
- James J Moran
- Signatures Science and Technology Division, National Security Directorate, Pacific Northwest National Laboratory, Richland, WA, 99352, USA
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42
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Leavitt WD, Cummins R, Schmidt ML, Sim MS, Ono S, Bradley AS, Johnston DT. Multiple sulfur isotope signatures of sulfite and thiosulfate reduction by the model dissimilatory sulfate-reducer, Desulfovibrio alaskensis str. G20. Front Microbiol 2014; 5:591. [PMID: 25505449 PMCID: PMC4243691 DOI: 10.3389/fmicb.2014.00591] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 10/20/2014] [Indexed: 11/13/2022] Open
Abstract
Dissimilatory sulfate reduction serves as a key metabolic carbon remineralization process in anoxic marine environments. Sulfate reducing microorganisms can impart a wide range in mass-dependent sulfur isotopic fractionation. As such, the presence and relative activity of these organisms is identifiable from geological materials. By extension, sulfur isotope records are used to infer the redox balance of marine sedimentary environments, and the oxidation state of Earth's oceans and atmosphere. However, recent work suggests that our understanding of microbial sulfate reduction (MSRs) may be missing complexity associated with the presence and role of key chemical intermediates in the reductive process. This study provides a test of proposed metabolic models of sulfate reduction by growing an axenic culture of the well-studied MSRs, Desulfovibrio alaskensis strain G20, under electron donor limited conditions on the terminal electron acceptors sulfate, sulfite or thiosulfate, and tracking the multiple S isotopic consequences of each condition set. The dissimilatory reduction of thiosulfate and sulfite produce unique minor isotope effects, as compared to the reduction of sulfate. Further, these experiments reveal a complex biochemistry associated with sulfite reduction. That is, under high sulfite concentrations, sulfur is shuttled to an intermediate pool of thiosulfate. Site-specific isotope fractionation (within thiosulfate) is very large ((34)ε ~ 30‰) while terminal product sulfide carries only a small fractionation from the initial sulfite ((34)ε < 10‰): a signature similar in magnitude to sulfate and thiosulfate reduction. Together these findings show that microbial sulfate reduction (MSR) is highly sensitive to the concentration of environmentally important sulfur-cycle intermediates (sulfite and thiosulfate), especially when thiosulfate and the large site-specific isotope effects are involved.
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Affiliation(s)
- William D. Leavitt
- Department of Earth and Planetary Sciences, Harvard UniversityCambridge, MA, USA
- Department of Earth and Planetary Sciences, Washington University in St. LouisSt. Louis, MO, USA
| | - Renata Cummins
- Department of Earth and Planetary Sciences, Harvard UniversityCambridge, MA, USA
| | - Marian L. Schmidt
- Department of Earth and Planetary Sciences, Harvard UniversityCambridge, MA, USA
- Department of Ecology and Evolutionary Biology, University of MichiganAnn Arbor, MI, USA
| | - Min S. Sim
- Department of Earth, Atmosphere and Planetary Science, Massachusetts Institute of TechnologyCambridge, MA, USA
- Division of Geological Sciences, California Institute of TechnologyPasadena, CA, USA
| | - Shuhei Ono
- Department of Earth, Atmosphere and Planetary Science, Massachusetts Institute of TechnologyCambridge, MA, USA
| | - Alexander S. Bradley
- Department of Earth and Planetary Sciences, Washington University in St. LouisSt. Louis, MO, USA
| | - David T. Johnston
- Department of Earth and Planetary Sciences, Harvard UniversityCambridge, MA, USA
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43
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Wilbanks EG, Jaekel U, Salman V, Humphrey PT, Eisen JA, Facciotti MT, Buckley DH, Zinder SH, Druschel GK, Fike DA, Orphan VJ. Microscale sulfur cycling in the phototrophic pink berry consortia of the Sippewissett Salt Marsh. Environ Microbiol 2014; 16:3398-415. [PMID: 24428801 PMCID: PMC4262008 DOI: 10.1111/1462-2920.12388] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Revised: 12/30/2013] [Accepted: 01/05/2014] [Indexed: 11/27/2022]
Abstract
Microbial metabolism is the engine that drives global biogeochemical cycles, yet many key transformations are carried out by microbial consortia over short spatiotemporal scales that elude detection by traditional analytical approaches. We investigate syntrophic sulfur cycling in the 'pink berry' consortia of the Sippewissett Salt Marsh through an integrative study at the microbial scale. The pink berries are macroscopic, photosynthetic microbial aggregates composed primarily of two closely associated species: sulfide-oxidizing purple sulfur bacteria (PB-PSB1) and sulfate-reducing bacteria (PB-SRB1). Using metagenomic sequencing and (34) S-enriched sulfate stable isotope probing coupled with nanoSIMS, we demonstrate interspecies transfer of reduced sulfur metabolites from PB-SRB1 to PB-PSB1. The pink berries catalyse net sulfide oxidation and maintain internal sulfide concentrations of 0-500 μm. Sulfide within the berries, captured on silver wires and analysed using secondary ion mass spectrometer, increased in abundance towards the berry interior, while δ(34) S-sulfide decreased from 6‰ to -31‰ from the exterior to interior of the berry. These values correspond to sulfate-sulfide isotopic fractionations (15-53‰) consistent with either sulfate reduction or a mixture of reductive and oxidative metabolisms. Together this combined metagenomic and high-resolution isotopic analysis demonstrates active sulfur cycling at the microscale within well-structured macroscopic consortia consisting of sulfide-oxidizing anoxygenic phototrophs and sulfate-reducing bacteria.
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Affiliation(s)
- Elizabeth G Wilbanks
- Department of Department of Microbiology Graduate Group, University of CaliforniaDavis, CA, 95616, USA
| | - Ulrike Jaekel
- Department of Evolution and Ecology, University of CaliforniaDavis, CA, 95616, USA
- Department of Microbiology and Immunology, University of CaliforniaDavis, CA, 95616, USA
| | - Verena Salman
- Department of Biomedical Engineering, University of CaliforniaDavis, CA, 95616, USA
| | - Parris T Humphrey
- UC Davis Genome Center, University of CaliforniaDavis, CA, 95616, USA
| | - Jonathan A Eisen
- Arctic Technology, Shell Technology NorwayOslo, N-0277, Norway
- Department of Organismic and Evolutionary Biology, Harvard UniversityCambridge, MA, 02138, USA
- Department of Marine Sciences, University of North Carolina at Chapel HillChapel Hill, NC, 27599, USA
| | - Marc T Facciotti
- Department of Marine Sciences, University of North Carolina at Chapel HillChapel Hill, NC, 27599, USA
- Ecology and Evolutionary Biology, University of ArizonaTucson, AZ, 85721, USA
| | - Daniel H Buckley
- Crop and Soil Sciences, Cornell UniversityIthaca, NY, 14853, USA
| | - Stephen H Zinder
- Department of Microbiology, Cornell UniversityIthaca, NY, 14853, USA
| | - Gregory K Druschel
- Department of Earth Sciences, Indiana University-Purdue UniversityIndianapolis, IN, 46202, USA
| | - David A Fike
- Department of Earth and Planetary Sciences, Washington UniversitySt. Louis, MO, 63130, USA
| | - Victoria J Orphan
- Division of Geological and Planetary Sciences, California Institute of TechnologyPasadena, CA, 91125, USA
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Houghton J, Fike D, Druschel G, Orphan V, Hoehler TM, Des Marais DJ. Spatial variability in photosynthetic and heterotrophic activity drives localized δ13C org fluctuations and carbonate precipitation in hypersaline microbial mats. GEOBIOLOGY 2014; 12:557-574. [PMID: 25312537 DOI: 10.1111/gbi.12113] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 08/30/2014] [Indexed: 06/04/2023]
Abstract
Modern laminated photosynthetic microbial mats are ideal environments to study how microbial activity creates and modifies carbon and sulfur isotopic signatures prior to lithification. Laminated microbial mats from a hypersaline lagoon (Guerrero Negro, Baja California, Mexico) maintained in a flume in a greenhouse at NASA Ames Research Center were sampled for δ(13) C of organic material and carbonate to assess the impact of carbon fixation (e.g., photosynthesis) and decomposition (e.g., bacterial respiration) on δ(13) C signatures. In the photic zone, the δ(13) C org signature records a complex relationship between the activities of cyanobacteria under variable conditions of CO2 limitation with a significant contribution from green sulfur bacteria using the reductive TCA cycle for carbon fixation. Carbonate is present in some layers of the mat, associated with high concentrations of bacteriochlorophyll e (characteristic of green sulfur bacteria) and exhibits δ(13) C signatures similar to DIC in the overlying water column (-2.0‰), with small but variable decreases consistent with localized heterotrophic activity from sulfate-reducing bacteria (SRB). Model results indicate respiration rates in the upper 12 mm of the mat alter in situ pH and HCO3- concentrations to create both phototrophic CO2 limitation and carbonate supersaturation, leading to local precipitation of carbonate minerals. The measured activity of SRB with depth suggests they variably contribute to decomposition in the mat dependent on organic substrate concentrations. Millimeter-scale variability in the δ(13) C org signature beneath the photic zone in the mat is a result of shifting dominance between cyanobacteria and green sulfur bacteria with the aggregate signature overprinted by heterotrophic reworking by SRB and methanogens. These observations highlight the impact of sedimentary microbial processes on δ(13) C org signatures; these processes need to be considered when attempting to relate observed isotopic signatures in ancient sedimentary strata to conditions in the overlying water column at the time of deposition and associated inferences about carbon cycling.
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Affiliation(s)
- J Houghton
- Department of Earth and Planetary Sciences, Washington University, St. Louis, MO, USA
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45
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Trimethylamine and Organic Matter Additions Reverse Substrate Limitation Effects on the δ13C Values of Methane Produced in Hypersaline Microbial Mats. Appl Environ Microbiol 2014; 80:7316-23. [PMID: 25239903 DOI: 10.1128/aem.02641-14] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Accepted: 09/12/2014] [Indexed: 11/20/2022] Open
Abstract
Methane production has been observed in a number of hypersaline environments, and it is generally thought that this methane is produced through the use of noncompetitive substrates, such as the methylamines, dimethylsulfide and methanol. Stable isotope measurements of the produced methane have also suggested that the methanogens are operating under conditions of substrate limitation. Here, substrate limitation in gypsum-hosted endoevaporite and soft-mat hypersaline environments was investigated by the addition of trimethylamine, a noncompetitive substrate for methanogenesis, and dried microbial mat, a source of natural organic matter. The δ(13)C values of the methane produced after amendments were compared to those in unamended control vials. At all hypersaline sites investigated, the δ(13)C values of the methane produced in the amended vials were statistically lower (by 10 to 71‰) than the unamended controls, supporting the hypothesis of substrate limitation at these sites. When substrates were added to the incubation vials, the methanogens within the vials fractionated carbon isotopes to a greater degree, resulting in the production of more (13)C-depleted methane. Trimethylamine-amended samples produced lower methane δ(13)C values than the mat-amended samples. This difference in the δ(13)C values between the two types of amendments could be due to differences in isotope fractionation associated with the dominant methane production pathway (or substrate used) within the vials, with trimethylamine being the main substrate used in the trimethylamine-amended vials. It is hypothesized that increased natural organic matter in the mat-amended vials would increase fermentation rates, leading to higher H2 concentrations and increased CO2/H2 methanogenesis.
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Pagès A, Grice K, Vacher M, Welsh DT, Teasdale PR, Bennett WW, Greenwood P. Characterizing microbial communities and processes in a modern stromatolite (Shark Bay) using lipid biomarkers and two-dimensional distributions of porewater solutes. Environ Microbiol 2014; 16:2458-74. [PMID: 24428563 DOI: 10.1111/1462-2920.12378] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2013] [Accepted: 12/31/2013] [Indexed: 11/29/2022]
Abstract
Modern microbial mats are highly complex and dynamic ecosystems. Diffusive equilibration in thin films (DET) and diffusive gradients in thin films (DGT) samplers were deployed in a modern smooth microbial mat from Shark Bay in order to observe, for the first time, two-dimensional distributions of porewater solutes during day and night time. Two-dimensional sulfide and alkalinity distributions revealed a strong spatial heterogeneity and a minor contribution of sulfide to alkalinity. Phosphate distributions were also very heterogeneous, while iron(II) distributions were quite similar during day and night with a few hotspots of mobilization. Lipid biomarkers from the three successive layers of the mat were also analysed in order to characterize the microbial communities regulating analyte distributions. The major hydrocarbon products detected in all layers included n-alkanes and isoprenoids, whilst other important biomarkers included hopanoids. Phospholipid fatty acid profiles revealed a decrease in cyanobacterial markers with depth, whereas sulfate-reducing bacteria markers increased in abundance in accordance with rising sulfide concentrations with depth. Despite the general depth trends in community structure and physiochemical conditions within the mat, two-dimensional solute distributions showed considerable small-scale lateral variability, indicating that the distributions and activities of the microbial communities regulating these solute distributions were equally heterogeneous and complex.
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Affiliation(s)
- Anais Pagès
- WA Organic & Isotope Geochemistry Centre, Department of Chemistry, Curtin University, GPO Box U1987, Perth, WA, 6845, Australia
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Hydrodynamics and collective behavior of the tethered bacterium Thiovulum majus. Proc Natl Acad Sci U S A 2014; 111:E537-45. [PMID: 24459183 DOI: 10.1073/pnas.1322092111] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The ecology and dynamics of many microbial systems, particularly in mats and soils, are shaped by how bacteria respond to evolving nutrient gradients and microenvironments. Here we show how the response of the sulfur-oxidizing bacterium Thiovulum majus to changing oxygen gradients causes cells to organize into large-scale fronts. To study this phenomenon, we develop a technique to isolate and enrich these bacteria from the environment. Using this enrichment culture, we observe the formation and dynamics of T. majus fronts in oxygen gradients. We show that these dynamics can be understood as occurring in two steps. First, chemotactic cells moving up the oxygen gradient form a front that propagates with constant velocity. We then show, through observation and mathematical analysis, that this front becomes unstable to changes in cell density. Random perturbations in cell density create oxygen gradients. The response of cells magnifies these gradients and leads to the formation of millimeter-scale fluid flows that actively pull oxygenated water through the front. We argue that this flow results from a nonlinear instability excited by stochastic fluctuations in the density of cells. Finally, we show that the dynamics by which these modes interact can be understood from the chemotactic response of cells. These results provide a mathematically tractable example of how collective phenomena in ecological systems can arise from the individual response of cells to a shared resource.
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48
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Cuomo C, Cochran JK, Turekian KK. Geochemistry of the Long Island Sound Estuary. SPRINGER SERIES ON ENVIRONMENTAL MANAGEMENT 2014. [DOI: 10.1007/978-1-4614-6126-5_4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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49
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Brady AL, Druschel G, Leoni L, Lim DSS, Slater GF. Isotopic biosignatures in carbonate-rich, cyanobacteria-dominated microbial mats of the Cariboo Plateau, B.C. GEOBIOLOGY 2013; 11:437-456. [PMID: 23941467 DOI: 10.1111/gbi.12050] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 07/09/2013] [Indexed: 06/02/2023]
Abstract
Photosynthetic activity in carbonate-rich benthic microbial mats located in saline, alkaline lakes on the Cariboo Plateau, B.C. resulted in pCO2 below equilibrium and δ(13) CDIC values up to +6.0‰ above predicted carbon dioxide (CO2 ) equilibrium values, representing a biosignature of photosynthesis. Mat-associated δ(13) Ccarb values ranged from ~4 to 8‰ within any individual lake, with observations of both enrichments (up to 3.8‰) and depletions (up to 11.6‰) relative to the concurrent dissolved inorganic carbon (DIC). Seasonal and annual variations in δ(13) C values reflected the balance between photosynthetic (13) C-enrichment and heterotrophic inputs of (13) C-depleted DIC. Mat microelectrode profiles identified oxic zones where δ(13) Ccarb was within 0.2‰ of surface DIC overlying anoxic zones associated with sulphate reduction where δ(13) Ccarb was depleted by up to 5‰ relative to surface DIC reflecting inputs of (13) C-depleted DIC. δ(13) C values of sulphate reducing bacteria biomarker phospholipid fatty acids (PLFA) were depleted relative to the bulk organic matter by ~4‰, consistent with heterotrophic synthesis, while the majority of PLFA had larger offsets consistent with autotrophy. Mean δ(13) Corg values ranged from -18.7 ± 0.1 to -25.3 ± 1.0‰ with mean Δ(13) Cinorg-org values ranging from 21.1 to 24.2‰, consistent with non-CO2 -limited photosynthesis, suggesting that Precambrian δ(13) Corg values of ~-26‰ do not necessitate higher atmospheric CO2 concentrations. Rather, it is likely that the high DIC and carbonate content of these systems provide a non-limiting carbon source allowing for expression of large photosynthetic offsets, in contrast to the smaller offsets observed in saline, organic-rich and hot spring microbial mats.
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Affiliation(s)
- A L Brady
- School of Geography and Earth Sciences, McMaster University, Hamilton, ON, Canada
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Al-Bader D, Kansour MK, Rayan R, Radwan SS. Biofilm comprising phototrophic, diazotrophic, and hydrocarbon-utilizing bacteria: a promising consortium in the bioremediation of aquatic hydrocarbon pollutants. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2013; 20:3252-3262. [PMID: 23089957 DOI: 10.1007/s11356-012-1251-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Accepted: 10/06/2012] [Indexed: 06/01/2023]
Abstract
Biofilms harboring simultaneously anoxygenic and oxygenic phototrophic bacteria, diazotrophic bacteria, and hydrocarbon-utilizing bacteria were established on glass slides suspended in pristine and oily seawater. Via denaturing gradient gel electrophoresis analysis on PCR-amplified rRNA gene sequence fragments from the extracted DNA from biofilms, followed by band amplification, biofilm composition was determined. The biofilms contained anoxygenic phototrophs belonging to alphaproteobacteria; pico- and filamentous cyanobacteria (oxygenic phototrophs); two species of the diazotroph Azospirillum; and two hydrocarbon-utilizing gammaproteobacterial genera, Cycloclasticus and Oleibacter. The coexistence of all these microbial taxa with different physiologies in the biofilm makes the whole community nutritionally self-sufficient and adequately aerated, a condition quite suitable for the microbial biodegradation of aquatic pollutant hydrocarbons.
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Affiliation(s)
- Dhia Al-Bader
- Department of Biological Sciences, Faculty of Science, Kuwait University, PO Box 5969, Safat 13060, Kuwait
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