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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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2
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Chen M, Conroy JL, Geyman EC, Sanford RA, Chee‐Sanford JC, Connor LM. Stable carbon isotope values of syndepositional carbonate spherules and micrite record spatial and temporal changes in photosynthesis intensity. GEOBIOLOGY 2022; 20:667-689. [PMID: 35851522 PMCID: PMC9543828 DOI: 10.1111/gbi.12509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 05/27/2022] [Accepted: 06/26/2022] [Indexed: 06/15/2023]
Abstract
Marine and lacustrine carbonate minerals preserve carbon cycle information, and their stable carbon isotope values (δ13 C) are frequently used to infer and reconstruct paleoenvironmental changes. However, multiple processes can influence the δ13 C values of bulk carbonates, confounding the interpretation of these values in terms of conditions at the time of mineral precipitation. Co-existing carbonate forms may represent different environmental conditions, yet few studies have analyzed δ13 C values of syndepositional carbonate grains of varying morphologies to investigate their origins. Here, we combine stable isotope analyses, metagenomics, and geochemical modeling to interpret δ13 C values of syndepositional carbonate spherules (>500 μm) and fine-grained micrite (<63 μm) from a ~1600-year-long sediment record of a hypersaline lake located on the coral atoll of Kiritimati, Republic of Kiribati (1.9°N, 157.4°W). Petrographic, mineralogic, and stable isotope results suggest that both carbonate fractions precipitate in situ with minor diagenetic alterations. The δ13 C values of spherules are high compared to the syndepositional micrite and cannot be explained by mineral differences or external perturbations, suggesting a role for local biological processes. We use geochemical modeling to test the hypothesis that the spherules form in the surface microbial mat during peak diurnal photosynthesis when the δ13 C value of dissolved inorganic carbon is elevated. In contrast, we hypothesize that the micrite may precipitate more continuously in the water as well as in sub-surface, heterotrophic layers of the microbial mat. Both metagenome and geochemical model results support a critical role for photosynthesis in influencing carbonate δ13 C values. The down-core spherule-micrite offset in δ13 C values also aligns with total organic carbon values, suggesting that the difference in the δ13 C values of spherules and micrite may be a more robust, inorganic indicator of variability in productivity and local biological processes through time than the δ13 C values of individual carbonate forms.
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Affiliation(s)
- Mingfei Chen
- Department of GeologyUniversity of Illinois at Urbana‐ChampaignUrbanaIllinoisUSA
| | - Jessica L. Conroy
- Department of GeologyUniversity of Illinois at Urbana‐ChampaignUrbanaIllinoisUSA
- Department of Plant BiologyUniversity of Illinois at Urbana‐ChampaignUrbanaIllinoisUSA
| | - Emily C. Geyman
- Division of Geological and Planetary SciencesCalifornia Institute of TechnologyPasadenaCaliforniaUSA
| | - Robert A. Sanford
- Department of GeologyUniversity of Illinois at Urbana‐ChampaignUrbanaIllinoisUSA
| | - Joanne C. Chee‐Sanford
- Department of Natural Resource and Environmental ScienceUniversity of Illinois at Urbana‐ChampaignUrbanaIllinoisUSA
- USDA‐ARSUrbanaIllinoisUSA
| | - Lynn M. Connor
- Department of Natural Resource and Environmental ScienceUniversity of Illinois at Urbana‐ChampaignUrbanaIllinoisUSA
- USDA‐ARSUrbanaIllinoisUSA
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3
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Waterworth SC, Isemonger EW, Rees ER, Dorrington RA, Kwan JC. Conserved bacterial genomes from two geographically isolated peritidal stromatolite formations shed light on potential functional guilds. ENVIRONMENTAL MICROBIOLOGY REPORTS 2021; 13:126-137. [PMID: 33369160 PMCID: PMC8408775 DOI: 10.1111/1758-2229.12916] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 11/17/2020] [Accepted: 12/06/2020] [Indexed: 05/24/2023]
Abstract
Stromatolites are complex microbial mats that form lithified layers. Fossilized stromatolites are the oldest evidence of cellular life on Earth, dating back over 3.4 billion years. Modern stromatolites are relatively rare but may provide clues about the function and evolution of their ancient counterparts. In this study, we focus on peritidal stromatolites occurring at Cape Recife and Schoenmakerskop on the southeastern South African coastline, the former being morphologically and structurally similar to fossilized phosphatic stromatolites formations. Using assembled shotgun metagenomic analysis, we obtained 183 genomic bins, of which the most dominant taxa were from the Cyanobacteria phylum. We identified functional gene sets in genomic bins conserved across two geographically isolated stromatolite formations, which included relatively high copy numbers of genes involved in the reduction of nitrates and phosphatic compounds. Additionally, we found little evidence of Archaeal species in these stromatolites, suggesting that they may not play an important role in peritidal stromatolite formations, as proposed for hypersaline formations.
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Affiliation(s)
- Samantha C. Waterworth
- Division of Pharmaceutical Sciences, University of Wisconsin, Madison, Wisconsin 53705, USA
| | - Eric W. Isemonger
- Department of Biochemistry and Microbiology, Rhodes University, Grahamstown, South Africa
| | - Evan R. Rees
- Division of Pharmaceutical Sciences, University of Wisconsin, Madison, Wisconsin 53705, USA
| | - Rosemary A. Dorrington
- Department of Biochemistry and Microbiology, Rhodes University, Grahamstown, South Africa
| | - Jason C. Kwan
- Division of Pharmaceutical Sciences, University of Wisconsin, Madison, Wisconsin 53705, USA
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4
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Depthwise microbiome and isotopic profiling of a moderately saline microbial mat in a solar saltern. Sci Rep 2020; 10:20686. [PMID: 33244085 PMCID: PMC7693307 DOI: 10.1038/s41598-020-77622-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 11/09/2020] [Indexed: 11/23/2022] Open
Abstract
The solar salterns in Tuticorin, India, are man-made, saline to hypersaline systems hosting some uniquely adapted populations of microorganisms and eukaryotic algae that have not been fully characterized. Two visually different microbial mats (termed ‘white’ and ‘green’) developing on the reservoir ponds (53 PSU) were isolated from the salterns. Firstly, archaeal and bacterial diversity in different vertical layers of the mats were analyzed. Culture-independent 16S rRNA gene analysis revealed that both bacteria and archaea were rich in their diversity. The top layers had a higher representation of halophilic archaea Halobacteriaceae, phylum Chloroflexi, and classes Anaerolineae, Delta- and Gamma- Proteobacteria than the deeper sections, indicating that a salinity gradient exists within the mats. Limited presence of Cyanobacteria and detection of algae-associated bacteria, such as Phycisphaerae, Phaeodactylibacter and Oceanicaulis likely implied that eukaryotic algae and other phototrophs could be the primary producers within the mat ecosystem. Secondly, predictive metabolic pathway analysis using the 16S rRNA gene data revealed that in addition to the regulatory microbial functions, methane and nitrogen metabolisms were prevalent. Finally, stable carbon and nitrogen isotopic compositions determined from both mat samples showed that the δ13Corg and δ15Norg values increased slightly with depth, ranging from − 16.42 to − 14.73‰, and 11.17 to 13.55‰, respectively. The isotopic signature along the microbial mat profile followed a pattern that is distinctive to the community composition and net metabolic activities, and comparable to saline mats in other salterns. The results and discussions presented here by merging culture-independent studies, predictive metabolic analyses and isotopic characterization, provide a collective strategy to understand the compositional and functional characteristics of microbial mats in saline environments.
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5
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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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6
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Buongiorno J, Gomez FJ, Fike DA, Kah LC. Mineralized microbialites as archives of environmental evolution, Laguna Negra, Catamarca Province, Argentina. GEOBIOLOGY 2019; 17:199-222. [PMID: 30548907 DOI: 10.1111/gbi.12327] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 10/16/2018] [Accepted: 10/26/2018] [Indexed: 06/09/2023]
Abstract
Environmental fluctuations are recorded in a variety of sedimentary archives of lacustrine depositional systems. Geochemical signals recovered from bottom sediments in closed-basin lakes are among the most sensitive paleoenvironmental indicators and are commonly used in reconstructing lake evolution. Microbialites (i.e., organosedimentary deposits accreted through microbial trapping and binding of detrital sediment or in situ mineral precipitation on organics [Palaios, 2, 1987, 241]), however, have been largely overlooked as paleoenvironmental repositories. Here, we investigate concentrically laminated mineralized microbialites from Laguna Negra, a high-altitude (4,100 m above sea level) hypersaline, closed-basin lake in northwestern Argentina, and explore the potential for recovery of environmental signals from these unique sedimentary archives. Spatial heterogeneity in hydrological regime helps define zones inside Laguna Negra, each with their own morphologically distinct microbialite type. Most notably, platey microbialites (in Zone 3A) are precipitated by evaporative concentration processes, while discoidal oncolites (in Zone 3C) are interpreted result from fluid mixing and biologically mediated nucleation. This spatial heterogeneity is reflected in petrographically distinct carbonate fabrics: micritic, botryoidal, and isopachous. Fabric type is interpreted to reflect a combination of physical and biological influences during mineralization, and paired C-isotope measurement of carbonate and organic matter supports ecological differences as a dominant control on C-isotopic evolution between zones. Laminae of Laguna Negra microbialites preserve a range of δ13 Ccarb from +5.75‰ to +18.25‰ and δ18 Ocarb from -2.04‰ to +9.28‰. Temporal trends of lower carbon and oxygen isotopic compositions suggest that the influence of CO2 degassing associated with evaporation has decreased over time. Combined, these results indicate that microbialite archives can provide data that aid in interpretation of both lake paleohydrology and paleoenvironmental change.
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Affiliation(s)
- Joy Buongiorno
- Department of Microbiology, The University of Tennessee, Knoxville, Tennessee
| | - Fernando J Gomez
- Centro de Investigaciones en Ciencias de la Tierra Cordoba, CONICET Cordoba, Córdoba, Argentina
| | - David A Fike
- Department of Earth & Planetary Sciences, Washington University, St. Louis, Missouri
| | - Linda C Kah
- Department of Earth & Planetary Sciences, The University of Tennessee, Knoxville, Tennessee
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7
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Farias ME, Rasuk MC, Gallagher KL, Contreras M, Kurth D, Fernandez AB, Poiré D, Novoa F, Visscher PT. Prokaryotic diversity and biogeochemical characteristics of benthic microbial ecosystems at La Brava, a hypersaline lake at Salar de Atacama, Chile. PLoS One 2017; 12:e0186867. [PMID: 29140980 PMCID: PMC5687714 DOI: 10.1371/journal.pone.0186867] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 10/09/2017] [Indexed: 11/19/2022] Open
Abstract
Benthic microbial ecosystems of Laguna La Brava, Salar de Atacama, a high altitude hypersaline lake, were characterized in terms of bacterial and archaeal diversity, biogeochemistry, (including O2 and sulfide depth profiles and mineralogy), and physicochemical characteristics. La Brava is one of several lakes in the Salar de Atacama where microbial communities are growing in extreme conditions, including high salinity, high solar insolation, and high levels of metals such as lithium, arsenic, magnesium, and calcium. Evaporation creates hypersaline conditions in these lakes and mineral precipitation is a characteristic geomicrobiological feature of these benthic ecosystems. In this study, the La Brava non-lithifying microbial mats, microbialites, and rhizome-associated concretions were compared to each other and their diversity was related to their environmental conditions. All the ecosystems revealed an unusual community where Euryarchaeota, Crenarchaeota, Acetothermia, Firmicutes and Planctomycetes were the most abundant groups, and cyanobacteria, typically an important primary producer in microbial mats, were relatively insignificant or absent. This suggests that other microorganisms, and possibly novel pathways unique to this system, are responsible for carbon fixation. Depth profiles of O2 and sulfide showed active production and respiration. The mineralogy composition was calcium carbonate (as aragonite) and increased from mats to microbialites and rhizome-associated concretions. Halite was also present. Further analyses were performed on representative microbial mats and microbialites by layer. Different taxonomic compositions were observed in the upper layers, with Archaea dominating the non-lithifying mat, and Planctomycetes the microbialite. The bottom layers were similar, with Euryarchaeota, Crenarchaeota and Planctomycetes as dominant phyla. Sequences related to Cyanobacteria were very scarce. These systems may contain previously uncharacterized community metabolisms, some of which may be contributing to net mineral precipitation. Further work on these sites might reveal novel organisms and metabolisms of biotechnological interest.
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Affiliation(s)
- Maria Eugenia Farias
- Laboratorio de Investigaciones Microbiológicas de Lagunas Andinas (LIMLA), Planta Piloto de Procesos Industriales Microbiológicos (PROIMI), CCT-Tucumán, CONICET, Tucumán, Argentina
- * E-mail:
| | - Maria Cecilia Rasuk
- Laboratorio de Investigaciones Microbiológicas de Lagunas Andinas (LIMLA), Planta Piloto de Procesos Industriales Microbiológicos (PROIMI), CCT-Tucumán, CONICET, Tucumán, Argentina
| | - Kimberley L. Gallagher
- Department of Marine Sciences, University of Connecticut, Groton, Connecticut, United States of America
| | | | - Daniel Kurth
- Laboratorio de Investigaciones Microbiológicas de Lagunas Andinas (LIMLA), Planta Piloto de Procesos Industriales Microbiológicos (PROIMI), CCT-Tucumán, CONICET, Tucumán, Argentina
| | - Ana Beatriz Fernandez
- Laboratorio de Investigaciones Microbiológicas de Lagunas Andinas (LIMLA), Planta Piloto de Procesos Industriales Microbiológicos (PROIMI), CCT-Tucumán, CONICET, Tucumán, Argentina
| | - Daniel Poiré
- Centro de Investigaciones Geológicas, Universidad Nacional de La Plata-Conicet, La Plata, Argentina
| | - Fernando Novoa
- Centro de Ecología Aplicada (CEA), Ñuñoa, Santiago, Chile
| | - Pieter T. Visscher
- Department of Marine Sciences, University of Connecticut, Groton, Connecticut, United States of America
- Australian Centre for Astrobiology, University of New South Wales, Sydney, New South Wales, Australia
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8
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Mobberley JM, Lindemann SR, Bernstein HC, Moran JJ, Renslow RS, Babauta J, Hu D, Beyenal H, Nelson WC. Organismal and spatial partitioning of energy and macronutrient transformations within a hypersaline mat. FEMS Microbiol Ecol 2017; 93:3071443. [PMID: 28334407 PMCID: PMC5812542 DOI: 10.1093/femsec/fix028] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 03/13/2017] [Indexed: 02/06/2023] Open
Abstract
Phototrophic mat communities are model ecosystems for studying energy cycling and elemental transformations because complete biogeochemical cycles occur over millimeter-to-centimeter scales. Characterization of energy and nutrient capture within hypersaline phototrophic mats has focused on specific processes and organisms; however, little is known about community-wide distribution of and linkages between these processes. To investigate energy and macronutrient capture and flow through a structured community, the spatial and organismal distribution of metabolic functions within a compact hypersaline mat community from Hot Lake have been broadly elucidated through species-resolved metagenomics and geochemical, microbial diversity and metabolic gradient measurements. Draft reconstructed genomes of 34 abundant organisms revealed three dominant cyanobacterial populations differentially distributed across the top layers of the mat suggesting niche separation along light and oxygen gradients. Many organisms contained diverse functional profiles, allowing for metabolic response to changing conditions within the mat. Organisms with partial nitrogen and sulfur metabolisms were widespread indicating dependence on metabolite exchange. In addition, changes in community spatial structure were observed over the diel. These results indicate that organisms within the mat community have adapted to the temporally dynamic environmental gradients in this hypersaline mat through metabolic flexibility and fluid syntrophic interactions, including shifts in spatial arrangements.
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Affiliation(s)
- Jennifer M Mobberley
- Biological Science Division, Earth and Environmental Science Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA
| | - Stephen R Lindemann
- Whistler Center for Carbohydrate Research, Department of Food Science, Purdue University, West Lafayette, IN 47907, USA.,Department of Nutrition Science, Purdue University, West Lafayette, IN 47907, USA
| | - Hans C Bernstein
- Biological Science Division, Earth and Environmental Science Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA.,The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164, USA
| | - James J Moran
- Chemical and Biological Signature Sciences, National Security Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA
| | - Ryan S Renslow
- Biological Science Division, Earth and Environmental Science Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA.,The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164, USA
| | - Jerome Babauta
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164, USA
| | - Dehong Hu
- Environmental Molecular Sciences Laboratory, Earth and Environmental Science Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA
| | - Haluk Beyenal
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164, USA
| | - William C Nelson
- Biological Science Division, Earth and Environmental Science Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA
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9
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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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10
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Cui H, Kaufman AJ, Xiao S, Peek S, Cao H, Min X, Cai Y, Siegel Z, Liu XM, Peng Y, Schiffbauer JD, Martin AJ. Environmental context for the terminal Ediacaran biomineralization of animals. GEOBIOLOGY 2016; 14:344-363. [PMID: 27038407 DOI: 10.1111/gbi.12178] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 01/19/2016] [Indexed: 06/05/2023]
Abstract
In terminal Ediacaran strata of South China, the onset of calcareous biomineralization is preserved in the paleontological transition from Conotubus to Cloudina in repetitious limestone facies of the Dengying Formation. Both fossils have similar size, funnel-in-funnel construction, and epibenthic lifestyle, but Cloudina is biomineralized, whereas Conotubus is not. To provide environmental context for this evolutionary milestone, we conducted a high-resolution elemental and stable isotope study of the richly fossiliferous Gaojiashan Member. Coincident with the first appearance of Cloudina is a significant positive carbonate carbon isotope excursion (up to +6‰) and an increase in the abundance and (34) S composition of pyrite. In contrast, δ(34) S values of carbonate-associated sulfate remain steady throughout the succession, resulting in anomalously large (>70‰) sulfur isotope fractionations in the lower half of the member. The fractionation trend likely relates to changes in microbial communities, with sulfur disproportionation involved in the lower interval, whereas microbial sulfate reduction was the principal metabolic pathway in the upper. We speculate that the coupled paleontological and biogeochemical anomalies may have coincided with an increase in terrestrial weathering fluxes of sulfate, alkalinity, and nutrients to the depositional basin, which stimulated primary productivity, the spread of an oxygen minimum zone, and the development of euxinic conditions in subtidal and basinal environments. Enhanced production and burial of organic matter is thus directly connected to the carbon isotope anomaly, and likely promoted pyritization as the main taphonomic pathway for Conotubus and other soft-bodied Ediacara biotas. Our studies suggest that the Ediacaran confluence of ecological pressures from predation and environmental pressures from an increase in seawater alkalinity set the stage for an unprecedented geobiological response: the evolutionary novelty of animal biomineralization.
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Affiliation(s)
- H Cui
- Department of Geology, University of Maryland, College Park, MD, USA
- Department of Geoscience and NASA Astrobiology Institute, University of Wisconsin-Madison, Madison, WI, USA
| | - A J Kaufman
- Department of Geology, University of Maryland, College Park, MD, USA
- Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD, USA
| | - S Xiao
- Department of Geosciences, Virginia Tech, Blacksburg, VA, USA
| | - S Peek
- Department of Geology, University of Maryland, College Park, MD, USA
| | - H Cao
- Department of Geology, University of Maryland, College Park, MD, USA
| | - X Min
- Department of Geology, Northwest University, Xi'an, China
| | - Y Cai
- Department of Geology, Northwest University, Xi'an, China
| | - Z Siegel
- Bethesda-Chevy Chase High School, Bethesda, MD, USA
| | - X-M Liu
- Department of Geological Sciences, University of North Carolina, Chapel Hill, NC, USA
| | - Y Peng
- Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA, USA
| | - J D Schiffbauer
- Department of Geological Sciences, University of Missouri, Columbia, MO, USA
| | - A J Martin
- División de Geociencias Aplicadas, IPICYT, San Luis Potosí, Mexico
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