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Alonso-Reyes DG, Galván FS, Irazoqui JM, Amadio A, Tschoeke D, Thompson F, Albarracín VH, Farias ME. Dissecting Light Sensing and Metabolic Pathways on the Millimeter Scale in High-Altitude Modern Stromatolites. MICROBIAL ECOLOGY 2022:10.1007/s00248-022-02112-7. [PMID: 36161499 DOI: 10.1007/s00248-022-02112-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 09/13/2022] [Indexed: 06/16/2023]
Abstract
Modern non-lithifying stromatolites on the shore of the volcanic lake Socompa (SST) in the Puna are affected by several extreme conditions. The present study assesses for the first time light utilization and functional metabolic stratification of SST on a millimeter scale through shotgun metagenomics. In addition, a scanning-electron-microscopy approach was used to explore the community. The analysis on SST unveiled the profile of a photosynthetic mat, with cyanobacteria not directly exposed to light, but placed just below a high-UV-resistant community. Calvin-Benson and 3-hydroxypropinate cycles for carbon fixation were abundant in upper, oxic layers, while the Wood-Ljungdahl pathway was dominant in the deeper anoxic strata. The high abundance of genes for UV-screening and oxidant-quenching pigments and CPF (photoreactivation) in the UV-stressed layers could indicate that the zone itself works as a UV shield. There is a remarkable density of sequences associated with photoreceptors in the first two layers. Also, genetic evidence of photosynthesis split in eukaryotic (layer 1) and prokaryotic (layer 2). Photoheterotrophic bacteria, aerobic photoautotrophic bacteria, and anaerobic photoautotrophic bacteria coexist by selectively absorbing different parts of the light spectrum (blue, red, and IR respectively) at different positions of the mat. Genes for oxygen, nitrogen, and sulfur metabolism account for the microelectrode chemical data and pigment measurements performed in previous publications. We also provide here an explanation for the vertical microbial mobility within the SST described previously. Finally, our study points to SST as ideal modern analogues of ancient ST.
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Affiliation(s)
- Daniel Gonzalo Alonso-Reyes
- Laboratorio de Microbiología Ultraestructural Y Molecular, Centro Integral de Microscopía Electrónica (CIME,), CONICET-Universidad Nacional de Tucumán, Camino de Sirga s/n, Finca El Manantial, Yerba Buena (4107), San Miguel de Tucumán, Tucumán, Argentina
- Laboratorio de Investigaciones Microbiológicas de Lagunas Andinas (LIMLA), Planta Piloto de Procesos Industriales y Microbiológicos (PROIMI), CCT, CONICET, Tucumán, Argentina
| | - Fátima Silvina Galván
- Laboratorio de Microbiología Ultraestructural Y Molecular, Centro Integral de Microscopía Electrónica (CIME,), CONICET-Universidad Nacional de Tucumán, Camino de Sirga s/n, Finca El Manantial, Yerba Buena (4107), San Miguel de Tucumán, Tucumán, Argentina
| | - José Matías Irazoqui
- Instituto de Investigación de La Cadena Láctea (INTA-CONICET), Rafaela, Argentina
| | - Ariel Amadio
- Instituto de Investigación de La Cadena Láctea (INTA-CONICET), Rafaela, Argentina
| | - Diogo Tschoeke
- Institute of Biology and Coppe, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Fabiano Thompson
- Institute of Biology and Coppe, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Virginia Helena Albarracín
- Laboratorio de Microbiología Ultraestructural Y Molecular, Centro Integral de Microscopía Electrónica (CIME,), CONICET-Universidad Nacional de Tucumán, Camino de Sirga s/n, Finca El Manantial, Yerba Buena (4107), San Miguel de Tucumán, Tucumán, Argentina.
- Facultad de Ciencias Naturales e Instituto Miguel Lillo, Universidad Nacional de Tucumán, Tucumán, Argentina.
| | - María Eugenia Farias
- Laboratorio de Investigaciones Microbiológicas de Lagunas Andinas (LIMLA), Planta Piloto de Procesos Industriales y Microbiológicos (PROIMI), CCT, CONICET, Tucumán, Argentina
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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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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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