Geobiology最新文献

{"title":"Evaluating Serpentinization as a Source of Phosphite to Microbial Communities in Hydrothermal Vents","authors":"Joanne S. Boden,&nbsp;Sanjoy M. Som,&nbsp;William J. Brazelton,&nbsp;Rika E. Anderson,&nbsp;Eva E. Stüeken","doi":"10.1111/gbi.70016","DOIUrl":"https://doi.org/10.1111/gbi.70016","url":null,"abstract":"<p>Previous studies have documented the presence of phosphite, a reduced and highly soluble form of phosphorus, in serpentinites, which has led to the hypothesis that serpentinizing hydrothermal vents could have been an important source of bioavailable phosphorus for early microbial communities in the Archean. Here, we test this hypothesis by evaluating the genomic hallmarks of phosphorus usage in microbial communities living in modern hydrothermal vents with and without influence from serpentinization. These genomic analyses are combined with results from a geochemical model that calculates phosphorus speciation during serpentinization as a function of temperature, water:rock ratio, and lithology at thermodynamic equilibrium. We find little to no genomic evidence of phosphite use in serpentinizing environments at the Voltri Massif or the Von Damm hydrothermal field at the Mid Cayman Rise, but relatively more in the Lost City hydrothermal field, Coast Range Ophiolite Microbial Observatory, The Cedars, and chimney samples from Old City hydrothermal field and Prony Bay hydrothermal field, as well as in the non-serpentinizing hydrothermal vents at Axial Seamount. Geochemical modeling shows that phosphite production is favored at ca 275°C–325°C and low water:rock ratios, which may explain previous observations of phosphite in serpentinite rocks; however, most of the initial phosphate is trapped in apatite during serpentinization, suppressing the absolute phosphite yield. As a result, phosphite from serpentinizing vents could have supported microbial growth around olivine minerals in chimney walls and suspended aggregates, but it is unlikely to have fueled substantial primary productivity in diffusely venting fluids during life's origin and evolution in the Archean unless substrates equivalent to dunites (composed of &gt; 90 wt% olivine) were more common.</p>","PeriodicalId":173,"journal":{"name":"Geobiology","volume":"23 2","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/gbi.70016","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143690138","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental Mineralisation of a Filamentous Hydrogenotrophic Methanogen in Carbonate, Phosphate, and Silicate","authors":"Sigrid Huld,&nbsp;Sean McMahon,&nbsp;Sebastian Willman,&nbsp;Anna Neubeck","doi":"10.1111/gbi.70014","DOIUrl":"https://doi.org/10.1111/gbi.70014","url":null,"abstract":"<p>Methanogenic archaea were likely among the earliest organisms to populate the Earth, perhaps contributing to the Archaean greenhouse effect; they are also widely discussed as analogues to any potential life on Mars. However, fossil evidence of archaea has been difficult to identify in the rock record, perhaps because their preservation potential is intrinsically low or because they are particularly small and difficult to identify. Here, we examined the preservation potential of a methanogen of the genus <i>Methanobacterium</i>, recently isolated from a low-temperature serpentinizing system, an environment somewhat analogous to habitats on the early Earth and Mars. Notably, this organism has a cell wall composed of peptidoglycan-like pseudomurein, which may imply a mineralisation potential similar to that of gram-positive bacteria. <i>Methanobacterium</i> cells were placed in carbonate, phosphate, and silicate solutions for up to 3 months in order to assess the relative tendency of these minerals to encrust and preserve cellular morphology. Cells readily acquired a thick, uniform coating of silica, enhancing their potential for long-term preservation while also increasing overall filament size, an effect that may aid the discovery of fossil archaea while hindering their interpretation. Phosphates precipitated from the medium in all experimental setups and even in parallel experiments set up with low-phosphate medium, suggesting a hitherto unknown biomineralisation capacity of methanogens. Carbonate precipitates did not form in close association with cells.</p>","PeriodicalId":173,"journal":{"name":"Geobiology","volume":"23 2","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/gbi.70014","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143629878","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An Anaerobic Microbial Community Mediates Epigenetic Native Sulfur and Carbonate Formation During Replacement of Messinian Gypsum at Monte Palco, Sicily","authors":"Simon E. Rouwendaal,&nbsp;Daniel Birgel,&nbsp;Marcello Natalicchio,&nbsp;Francesco Dela Pierre,&nbsp;Laetitia Guibourdenche,&nbsp;Thorsten Bauersachs,&nbsp;Giovanni Aloisi,&nbsp;Amanda L. Labrado,&nbsp;Benjamin Brunner,&nbsp;Jörn Peckmann","doi":"10.1111/gbi.70015","DOIUrl":"https://doi.org/10.1111/gbi.70015","url":null,"abstract":"<p>The microbially mediated replacement of sulfate-bearing evaporites by authigenic carbonate and native sulfur under anoxic conditions is poorly understood. Sulfur-bearing carbonates from the Monte Palco ridge (Sicily) replacing Messinian gypsum were therefore studied to better characterize the involved microorganisms. The lack of (1) sedimentary bedding, (2) lamination, and (3) significant water-column-derived lipid biomarkers in the secondary carbonates implies replacement after gypsum deposition (epigenesis). Allochthonous clasts from the older Calcare di Base and the younger Trubi Formation within these carbonates further evidence epigenetic formation. The sulfur-bearing carbonates are significantly ¹³C-depleted (δ¹³C as low as −51‰), identifying methane as a major carbon source. The ¹⁸O-enrichment of the carbonates (δ¹⁸O as high as 5.4‰) probably reflects precipitation from ¹⁸O-enriched fluids transported along adjacent faults or precipitation in a closed system with very little water. Native sulfur with variable ³⁴S-enrichment (δ³⁴S as high as 18.9‰), a relatively small maximum offset (12.3‰) between the sulfate source (gypsum) and native sulfur, and high δ³⁴S values of carbonate-associated sulfate (as high as 61.1‰) suggest a high conversion to native sulfur in a (semi-)closed system, with insignificant sulfate removal. Anaerobic methanotrophic archaea (ANME) apparently affiliated with the ANME-1 clade mediated secondary mineral formation as evidenced by the biomarker inventory, which contains abundant ¹³C-depleted isoprenoids including <i>sn3</i>-hydroxyarchaeol as the sole hydroxyarchaeol isomer and glycerol dibiphytanyl glycerol tetraethers (GDGTs). A series of various, tentatively identified ¹³C-depleted non-isoprenoidal dialkyl glycerol diethers (DAGEs), 10me-C₁₆ fatty acid, hydroxy C₁₆ fatty acids, and cyclopropyl-C_17:0ω7,8 fatty acid agree with sulfate-reducing bacteria participating in the anaerobic oxidation of methane. Specific conditions during gypsum replacement, unlike those at marine methane seeps, are reflected by the occurrence of ¹³C-depleted lipids such as lycopane, 9me-C₁₇ fatty acid, and novel DAGEs. As a response to a confined environment probably characterized by high sulfate concentrations, sulfidic conditions, and elevated salinity, ANMEs and sulfate-reducing bacteria apparently adapted their membrane compositions to cope with such stressors.</p>","PeriodicalId":173,"journal":{"name":"Geobiology","volume":"23 2","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/gbi.70015","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143555086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microbial Cycling of Sulfur and Other Redox-Sensitive Elements in Porewaters of San Clemente Basin, California, and Cocos Ridge, Costa Rica","authors":"Daniela Osorio-Rodriguez,&nbsp;Frank J. Pavia,&nbsp;Daniel R. Utter,&nbsp;Matthew Quinan,&nbsp;Kameko Landry,&nbsp;Maya Gomes,&nbsp;Nathan D. Dalleska,&nbsp;Victoria J. Orphan,&nbsp;William M. Berelson,&nbsp;Jess F. Adkins","doi":"10.1111/gbi.70013","DOIUrl":"https://doi.org/10.1111/gbi.70013","url":null,"abstract":"<div>\u0000 \u0000 <p>The microbial recycling of organic matter in marine sediments depends upon electron acceptors that are utilized based on availability and energetic yield. Since sulfate is the most abundant oxidant once oxygen has been depleted, the sulfide produced after sulfate reduction becomes an important electron donor for autotrophic microbes. The ability of sulfide to be re-oxidized through multiple metabolic pathways and intermediates with variable oxidation states prompts investigation into which species are preferentially utilized and what are the factors that determine the fate of reduced sulfur species. Quantifying these sulfur intermediates in porewaters is a critical first step towards achieving a more complete understanding of the oxidative sulfur cycle, yet this has been accomplished in very few studies, none of which include oligotrophic sedimentary environments in the open ocean. Here we present profiles of porewater sulfur intermediates from sediments underlying oligotrophic regions of the ocean, which encompass about 75% of the ocean's surface and are characterized by low nutrient levels and productivity. Aiming at addressing uncertainties about if and how sulfide produced by the degradation of scarce sedimentary organic matter plays a role in carbon fixation in the sediment, we determine depth profiles of redox-sensitive metals and sulfate isotope compositions and integrate these datasets with 16S rRNA microbial community composition data and solid-phase sulfur concentrations. We did not find significant correlations between sulfur species or trace metals and specific sulfur cycling taxa, which suggests that microorganisms in pelagic and oxic sediments may be generalists utilizing flexible metabolisms to oxidize organic matter through different electron acceptors.</p>\u0000 </div>","PeriodicalId":173,"journal":{"name":"Geobiology","volume":"23 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143446821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Untangling the Primary Biotic and Abiotic Controls on Oxygen, Inorganic and Organic Carbon Isotope Signals in Modern Microbialites","authors":"Robin Havas,&nbsp;Christophe Thomazo,&nbsp;Jeanne Caumartin,&nbsp;Miguel Iniesto,&nbsp;Hugo Bert,&nbsp;Didier Jézéquel,&nbsp;David Moreira,&nbsp;Rosaluz Tavera,&nbsp;Vladimir Bettencourt,&nbsp;Purificación López-García,&nbsp;Emmanuelle Vennin,&nbsp;Karim Benzerara","doi":"10.1111/gbi.70012","DOIUrl":"https://doi.org/10.1111/gbi.70012","url":null,"abstract":"<p>Microbialites are organo-sedimentary structures formed throughout most of the Earth history, over a wide range of geological contexts, and under a multitude of environmental conditions affecting their composition. The carbon and oxygen isotope records of carbonates, which are most often their main constituents, have been used as a widespread tool for paleoenvironmental reconstructions. However, the multiplicity of factors that influence microbialites formation is not always properly distinguished in their isotopic record, in both ancient and modern settings. It is therefore crucial to refine our understanding of the processes controlling microbialites isotopic signal. Here, we analyzed the carbon and oxygen isotope compositions from bulk and micro-drilled carbonates as well as bulk organic carbon isotope compositions in microbialites from four Mexican volcanic crater lakes of increasing alkalinity. The survey of four lakes allows comparing microbialite formation processes and their geochemical record within distinct physico-chemical contexts. The geochemical analyses were performed in parallel to petrographic and mineralogical characterization and interpreted in light of the known microbial community composition for microbialites of the same lakes. Combining these data, we show that the potential for isotopic biosignature preservation primarily depends on physico-chemical conditions. Carbon isotope biosignatures pointing out to an autotrophic influence on carbonate precipitation are preserved in the lowest alkalinity lakes. By contrast, higher alkalinity lakes, where microbialites are more massive, favor carbonate precipitation in isotopic equilibrium with the lake water, with secondary influence of heterotrophic organic carbon degradation. From these results, we suggest that microbialite carbonate C isotope records can be interpreted as the balance between the microbialite net primary productivity and the amount of precipitation that relates to physico-chemical forcing. The signals of microbialite oxygen isotope compositions highlight a lack of understanding in the oxygen isotope records of relatively rare carbonate phases such as hydromagnesite. Nonetheless, we show that these signals are primarily influenced by the basins' hydrology, though biological effects may also play a (minor) role. Overall, both carbon and oxygen isotopic signals may record a mixture of different local/global and biotic/abiotic phenomena, making microbialites intricate archives of their growth environment, which should thus be interpreted with cautions and in the light of their surrounding sediments.</p>","PeriodicalId":173,"journal":{"name":"Geobiology","volume":"23 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/gbi.70012","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143423638","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"How to Make a Rock in 150 Days: Observations of Biofilms Promoting Rapid Beachrock Formation","authors":"Brianna M. Hibner,&nbsp;Marjorie D. Cantine,&nbsp;Elizabeth J. Trower,&nbsp;Jacqueline E. Dodd,&nbsp;Maya L. Gomes","doi":"10.1111/gbi.70009","DOIUrl":"https://doi.org/10.1111/gbi.70009","url":null,"abstract":"<div>\u0000 \u0000 <p>Beachrock is a type of carbonate-cemented rock that forms via rapid cementation in the intertidal zone. Beachrock is a valuable geological tool as an indicator of paleoshorelines and may protect shorelines from erosion. Previous studies present a range of hypotheses about the processes enabling rapid beachrock formation, which span purely physicochemical mechanisms to a significant role for microbially mediated carbonate precipitation. We designed a set of in situ field experiments to explore the rates and mechanisms of beachrock formation on Little Ambergris Cay (Turks and Caicos Islands). Our field site has evidence for rapid beachrock cementation, including the incorporation of 20th century anthropogenic detritus into beachrock. We deployed pouches of sterilized ooid sand in the upper intertidal zone and assessed the extent of cementation and biofilm development after durations of 4 days, 2.5 months, and 5 months. We observed incipient meniscus cements after only 4 days of incubation in the field, suggesting that physicochemical processes are important in driving initial cementation. After 2.5 months, we observed substantial biofilm colonization on our experimental substrates, with interwoven networks of <i>Halomicronema</i> filaments binding clusters of ooids to the nylon pouches. After 5 months, we observed incipient beachrock formation in the form of coherent aggregates of ooids up to 1 cm in diameter, bound together by both networks of microbial filaments and incipient cements. We interpret that the cyanobacteria-dominated beachrock biofilm community on Little Ambergris Cay plays an important role in beachrock formation through the physical stabilization of sediment as cementation proceeds. Together, this combination of physicochemical and microbial mechanisms enables fresh rock to form in as little as 150 days.</p>\u0000 </div>","PeriodicalId":173,"journal":{"name":"Geobiology","volume":"23 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143362586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Growth of Microbial Mats on Hard Nuclei in Shallow Sandy Environments","authors":"Kendall Valentine,&nbsp;Tanja Bosak,&nbsp;Maria Kondrat'yev,&nbsp;Vanja Klepac-Ceraj,&nbsp;Ashley S. Kleinman,&nbsp;Rebecca Rubinstein,&nbsp;Giulio Mariotti","doi":"10.1111/gbi.70011","DOIUrl":"https://doi.org/10.1111/gbi.70011","url":null,"abstract":"<div>\u0000 \u0000 <p>The growth of most stromatolites is a result of interactions among the growth of microbial mats, mineral precipitation, water flow, and sediment movement. Here, we ask how oxygenic photosynthetic microbes colonize surfaces and interact with sediments in high-energy environments that contain constantly moving sand. For this, we investigate cyanobacterial growth on centimeter-scale concrete spheres in a continuously agitated wave tank. Cyanobacteria are unable to colonize moving sand, but establish biofilms on spheres within 5–6 weeks. These biofilms trap up to 0.5 g/cm² of sand on the top and 0.3 g/cm² on the sides within 25 weeks. The colonization does not depend on the size of the spheres, but instead depends on their surface roughness. Cyanobacteria easily colonize spheres with a surface roughness that matches the bed grain size (0.3 mm), but cannot colonize the initial topographic highs with a roughness of ~0.001 mm. In both cases, recesses on the surfaces of the spheres protect cyanobacteria from sandblasting. Thus, microbial biofilms can become established even in high-energy environments, if topographic highs are large enough not to be rolled around by the flow and rough enough to provide attachment loci. If cementation occurs within biofilms, the interplay among biofilm growth, sediment trapping, and cementation can lead to the upward as well as lateral growth of stromatolites. These experimental observations can explain the preferential upward growth of stromatolites on topographic highs in areas with frequently mobilized sediment grains, including modern stromatolites in the intertidal zone in Shark Bay and the subtidal zone in The Bahamas.</p>\u0000 </div>","PeriodicalId":173,"journal":{"name":"Geobiology","volume":"23 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143362587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microbially Enhanced Growth and Metal Capture by Ferromanganese Concretions in a Laboratory Experiment","authors":"Renata Majamäki,&nbsp;Joonas Wasiljeff,&nbsp;Lotta Purkamo,&nbsp;Jenni Hultman,&nbsp;Eero Asmala,&nbsp;Pirjo Yli-Hemminki,&nbsp;Kirsten S. Jørgensen,&nbsp;Karoliina Koho,&nbsp;Jukka Kuva,&nbsp;Joonas J. Virtasalo","doi":"10.1111/gbi.70010","DOIUrl":"10.1111/gbi.70010","url":null,"abstract":"<div>\u0000 \u0000 <p>The growth and metal enrichment of ferromanganese minerals on the seafloor have intrigued many studies, yet the role of microbes in the process has remained elusive. Here, we assessed the microbial influence on the growth and trace metal accumulation and release of ferromanganese concretions from the Baltic Sea using 12-week microcosm incubation experiments. We studied three concretion morphotypes: Crust, discoidal, and spheroidal, with biotic and abiotic treatments. The concretion samples were collected into bottles containing artificial brackish seawater from the Gulf of Finland, incubated in in-situ simulating conditions, and sampled at the beginning and end of the experiment. Microscale X-ray-computed tomography confirmed the local growth of up to 10 μm thick patches on the concretion surface during the 12-week incubation period, corresponding to a growth rate of 0.04 mm/year. Scanning electron microscopy of glass slides in the microcosms revealed freshly precipitated cauliflower-like grains, typical of freshly formed Fe- and Mn-hydroxides. Decreased concentrations of dissolved trace metals (Mn, Fe Co, V, Ni, Zn, and Mo) in the incubation solutions indicated the accumulation of these elements into concretions in the biotic microcosms. In contrast, the dissolution of concretions was observed in abiotic microcosms, confirming that microbial activity enhanced the ferromanganese precipitation and the associated accumulation and release of P and trace metals into the ambient solution. The microbial contribution was confirmed by a strong decrease in headspace methane concentrations in biotic microcosms, further indicating the presence of active methanotrophs in the concretion communities.</p>\u0000 </div>","PeriodicalId":173,"journal":{"name":"Geobiology","volume":"23 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143078262","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cyanobacteria Boring Limestones in Freshwater Settings—Their Pioneering Role in Sculpturing Pebbles and Carbonate Dissolution","authors":"Andreas Wetzel,&nbsp;Jakob Zopfi,&nbsp;Alfred Uchman","doi":"10.1111/gbi.70006","DOIUrl":"10.1111/gbi.70006","url":null,"abstract":"<div>\u0000 \u0000 <p>In freshwater lakes and rivers, cyanobacteria belonging to the family Leptolyngbyaceae bore &gt; 1 mm deep into limestone pebbles by dissolving carbonate at the tip of their 3–8 μm-thick filaments. The abundance of these borings decreases downward while it is so high at the rock surface that micrometric debris is formed. Moreover, the disintegrated material on the pebbles' surface can be easily removed, for instance, when pebbles are grinding against each other due to wave or current action or when insect larvae settle and scratch loosened grains from the surface while constructing their cases. After a larvae case has been abandoned, it decays with time and the surface benath it is colonized again by boring cyanobacteria. These processes can alternate repeatedly and lead to a sculptured appearance of the pebbles, especially because insect larvae tend to colonize already existing depressions where they are better protected from predation and where they can access suspended food more easily. In the sculptures entrenched by insect larvae, larvae of byssate bivalves like <i>Dreissena polymorpha</i> may settle. When growing, these bivalves also remove loosened carbonate from the bored surface. Thus, boring cyanobacteria play a pioneering, preconditioning role in the morphological evolution of limestone (pebble) surfaces by transforming an initially hard substrate into a firm- to softground that is subsequently colonized and structured by animals. Consequently, sculptured pebbles are the product of multiphase, preconditioned bioerosion. Ultimately, the synergistic effects of these bioerosive processes result in the dissolution of carbonate leading to a maximum take-up of approximately 0.5–0.8 kg CO₂ per square meter and year, as a preliminary estimate indicates.</p>\u0000 </div>","PeriodicalId":173,"journal":{"name":"Geobiology","volume":"23 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142890713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Early-Branching Cyanobacteria Grow Faster and Upregulate Superoxide Dismutase Activity Under a Simulated Early Earth Anoxic Atmosphere","authors":"Sadia S. Tamanna,&nbsp;Joanne S. Boden,&nbsp;Kimberly M. Kaiser,&nbsp;Nicola Wannicke,&nbsp;Jonas Höring,&nbsp;Patricia Sánchez-Baracaldo,&nbsp;Marcel Deponte,&nbsp;Nicole Frankenberg-Dinkel,&nbsp;Michelle M. Gehringer","doi":"10.1111/gbi.70005","DOIUrl":"10.1111/gbi.70005","url":null,"abstract":"<p>The evolution of oxygenic photosynthesis during the Archean (4–2.5 Ga) required the presence of complementary reducing pathways to maintain the cellular redox balance. While the timing of the evolution of superoxide dismutases (SODs), enzymes that convert superoxide to hydrogen peroxide and O₂, within bacteria and archaea is not resolved, the first SODs appearing in cyanobacteria contained copper and zinc in the reaction center (CuZnSOD). Here, we analyse growth characteristics, SOD gene expression (qRT-PCR) and cellular enzyme activity in the deep branching strain, <i>Pseudanabaena</i> sp. PCC7367, previously demonstrated to release significantly more O₂ under anoxic conditions. The observed significantly higher growth rates (<i>p</i> &lt; 0.001) and protein and glycogen contents (<i>p</i> &lt; 0.05) in anoxically cultured <i>Pseudanabaena</i> PCC7367 compared to control cultures grown under present-day oxygen-rich conditions prompted the following question: Is the growth of <i>Pseudanabaena</i> sp. PCC7367 correlated to atmospheric <i>p</i>O₂ and cellular SOD activity? Expression of <i>sodB</i> (encoding FeSOD) and <i>sodC</i> (encoding CuZnSOD) strongly correlated with medium O₂ levels (<i>p</i> &lt; 0.001). Expression of <i>sodA</i> (encoding MnSOD) correlated significantly to SOD activity during the day (<i>p</i> = 0.019) when medium O₂ concentrations were the highest. The cellular SOD enzyme activity of anoxically grown cultures was significantly higher (<i>p</i> &lt; 0.001) 2 h before the onset of the dark phase compared to O₂-rich growth conditions. The expression of SOD encoding genes was significantly reduced (<i>p</i> &lt; 0.05) under anoxic conditions in stirred cultures, as were medium O₂ levels (<i>p</i> ≤ 0.001), compared to oxic-grown cultures, whereas total cellular SOD activity remained comparable. Our data suggest that increasing <i>p</i>O₂ negatively impacts the viability of early cyanobacteria, possibly by increasing photorespiration. Additionally, the increased expression of superoxide-inactivating genes during the dark phase suggests the increased replacement rates of SODs under modern-day conditions compared to those on early Earth.</p>","PeriodicalId":173,"journal":{"name":"Geobiology","volume":"22 6","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11636452/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142811690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}