Geobiology最新文献

{"title":"Production of diverse brGDGTs by Acidobacterium Solibacter usitatus in response to temperature, pH, and O2 provides a culturing perspective on brGDGT proxies and biosynthesis","authors":"Toby A. Halamka,&nbsp;Jonathan H. Raberg,&nbsp;Jamie M. McFarlin,&nbsp;Adam D. Younkin,&nbsp;Christopher Mulligan,&nbsp;Xiao-Lei Liu,&nbsp;Sebastian H. Kopf","doi":"10.1111/gbi.12525","DOIUrl":"https://doi.org/10.1111/gbi.12525","url":null,"abstract":"<p>Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are bacterial membrane lipids that are frequently employed as paleoenvironmental proxies because of the strong empirical correlations between their relative abundances and environmental temperature and pH. Despite the ubiquity of brGDGTs in modern and paleoenvironments, the source organisms of these enigmatic compounds have remained elusive, requiring paleoenvironmental applications to rely solely on observed environmental correlations. Previous laboratory and environmental studies have suggested that the globally abundant bacterial phylum of the Acidobacteria may be an important brGDGT producer in nature. Here, we report on experiments with a cultured Acidobacterium, <i>Solibacter usitatus</i>, that makes a large portion of its cellular membrane (24 ± 9% across all experiments) out of a structurally diverse set of tetraethers including the common brGDGTs Ia, IIa, IIIa, Ib, and IIb. <i>Solibacter usitatus</i> was grown across a range of conditions including temperatures from 15 to 30°C, pH from 5.0 to 6.5, and O₂ from 1% to 21%, and demonstrated pronounced shifts in the degree of brGDGT methylation across these growth conditions. The temperature response in culture was in close agreement with trends observed in published environmental datasets, supporting a physiological basis for the empirical relationship between brGDGT methylation number and temperature. However, brGDGT methylation at lower temperatures (15 and 20°C) was modulated by culture pH with higher pH systematically increasing the degree of methylation. In contrast, pH had little effect on brGDGT cyclization, supporting the hypothesis that changes in bacterial community composition may underlie the link between cyclization number and pH observed in environmental samples. Oxygen concentration likewise affected brGDGT methylation highlighting the potential for this environmental parameter to impact paleotemperature reconstruction. Low O₂ culture conditions further resulted in the production of uncommon brGDGT isomers that could be indicators of O₂ limitation. Finally, the production of brGTGTs (trialkyl tetraethers) in addition to the previously discovered iso-C15-based mono- and diethers in <i>S. usitatus</i> suggests a potential biosynthetic pathway for brGDGTs that uses homologs of the archaeal tetraether synthase (Tes) enzyme for tetraether synthesis from diethers.</p>","PeriodicalId":173,"journal":{"name":"Geobiology","volume":"21 1","pages":"102-118"},"PeriodicalIF":3.7,"publicationDate":"2022-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/gbi.12525","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"6012816","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":"Exploring the secondary mineral products generated by microbial iron respiration in Archean ocean simulations","authors":"Christine Nims,&nbsp;Jena E. Johnson","doi":"10.1111/gbi.12523","DOIUrl":"https://doi.org/10.1111/gbi.12523","url":null,"abstract":"<p>Marine chemical sedimentary deposits known as Banded Iron Formations (BIFs) archive Archean ocean chemistry and, potentially, signs of ancient microbial life. BIFs contain a diversity of iron- and silica-rich minerals in disequilibrium, and thus many interpretations of these phases suggest they formed secondarily during early diagenetic processes. One such hypothesis posits that the early diagenetic microbial respiration of primary iron(III) oxides in BIFs resulted in the formation of other iron phases, including the iron-rich silicates, carbonates, and magnetite common in BIF assemblages. Here, we simulated this proposed pathway in laboratory incubations combining a model dissimilatory iron-reducing (DIR) bacterium, <i>Shewanella putrefaciens</i> CN32, and the ferric oxyhydroxide mineral ferrihydrite under conditions mimicking the predicted Archean seawater geochemistry. We assessed the impact of dissolved silica, calcium, and magnesium on the bioreduced precipitates. After harvesting the solid products from these experiments, we analyzed the reduced mineral phases using Raman spectroscopy, electron microscopy, powder x-ray diffraction, and spectrophotometric techniques to identify mineral precipitates and track the bulk distributions of Fe(II) and Fe(III). These techniques detected a diverse range of calcium carbonate morphologies and polymorphism in incubations with calcium, as well as secondary ferric oxide phases like goethite in silica-free experiments. We also identified aggregates of curling, iron- and silica-rich amorphous precipitates in all incubations amended with silica. Although ferric oxides persist even in our electron acceptor-limited incubations, our observations indicate that microbial iron reduction of ferrihydrite is a viable pathway for the formation of early iron silicate phases. This finding allows us to draw parallels between our experimental proto-silicates and the recently characterized iron silicate nanoinclusions in BIF chert deposits, suggesting that early iron silicates could possibly be signatures of iron-reducing metabolisms on early Earth.</p>","PeriodicalId":173,"journal":{"name":"Geobiology","volume":"20 6","pages":"743-763"},"PeriodicalIF":3.7,"publicationDate":"2022-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/gbi.12523","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"6182599","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":"Physiological and metabolic responses of chemolithoautotrophic \u0000 \u0000 \u0000 \u0000 NO\u0000 3\u0000 −\u0000 \u0000 \u0000 reducers to high hydrostatic pressure","authors":"Ileana Pérez-Rodríguez,&nbsp;Stefan M. Sievert,&nbsp;Marilyn L. Fogel,&nbsp;Dionysis I. Foustoukos","doi":"10.1111/gbi.12522","DOIUrl":"https://doi.org/10.1111/gbi.12522","url":null,"abstract":"&lt;p&gt;We investigated the impact of pressure on thermophilic, chemolithoautotrophic &lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msubsup&gt;\u0000 &lt;mi&gt;NO&lt;/mi&gt;\u0000 &lt;mn&gt;3&lt;/mn&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;/msubsup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; reducing bacteria of the phyla &lt;i&gt;Campylobacterota&lt;/i&gt; and &lt;i&gt;Aquificota&lt;/i&gt; isolated from deep-sea hydrothermal vents. Batch incubations at 5 and 20 MPa resulted in decreased &lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msubsup&gt;\u0000 &lt;mi&gt;NO&lt;/mi&gt;\u0000 &lt;mn&gt;3&lt;/mn&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;/msubsup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; consumption, lower cell concentrations, and overall slower growth in &lt;i&gt;Caminibacter mediatlanticus&lt;/i&gt; (&lt;i&gt;Campylobacterota&lt;/i&gt;) and &lt;i&gt;Thermovibrio ammonificans&lt;/i&gt; (&lt;i&gt;Aquificota&lt;/i&gt;), relative to batch incubations near standard pressure (0.2 MPa) conditions. Nitrogen isotope fractionation effects from chemolithoautotrophic &lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msubsup&gt;\u0000 &lt;mi&gt;NO&lt;/mi&gt;\u0000 &lt;mn&gt;3&lt;/mn&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;/msubsup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; reduction by both microorganisms were, on the contrary, maintained under all pressure conditions. Comparable chemolithoautotrophic &lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msubsup&gt;\u0000 &lt;mi&gt;NO&lt;/mi&gt;\u0000 &lt;mn&gt;3&lt;/mn&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;/msubsup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; reducing activities between previously reported natural hydrothermal vent fluid microbial communities dominated by &lt;i&gt;Campylobacterota&lt;/i&gt; at 25 MPa and &lt;i&gt;Campylobacterota&lt;/i&gt; laboratory isolates at 0.2 MPa, suggest robust similarities in cell-specific &lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msubsup&gt;\u0000 &lt;mi&gt;NO&lt;/mi&gt;\u0000 &lt;mn&gt;3&lt;/mn&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;/msubsup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; reduction rates and doubling times between microbial populations and communities growing maximally under similar temperature conditions. Physiological and metabolic comparisons of our results with other studies of pressure effects on anaerobic chemolithoautotrophic processes (i.e., microbial S&lt;sup&gt;0&lt;/sup&gt;-oxidation coupled to Fe(III) reduction and hydrogenotrophic methanogenesis) suggest that anaerobic chemolithoautotrophs relying on oxidation–reduction (redox) reactions that yield higher Gibbs energies experience larger shifts in cell-specific respiration rates and doubling times at increased pressures. Overall, our results advance understanding of the role of pressure, its relationship with temperature and r","PeriodicalId":173,"journal":{"name":"Geobiology","volume":"20 6","pages":"857-869"},"PeriodicalIF":3.7,"publicationDate":"2022-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5768156","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":"Branching archaeocyaths as ecosystem engineers during the Cambrian radiation","authors":"Ryan A. Manzuk,&nbsp;Adam C. Maloof,&nbsp;Jaap A. Kaandorp,&nbsp;Mark Webster","doi":"10.1111/gbi.12521","DOIUrl":"https://doi.org/10.1111/gbi.12521","url":null,"abstract":"<p>The rapid origination and diversification of major animal body plans during the early Cambrian coincide with the rise of Earth's first animal-built framework reefs. Given the importance of scleractinian coral reefs as ecological facilitators in modern oceans, we investigate the impact of archaeocyathan (Class Archaeocyatha) reefs as engineered ecosystems during the Cambrian radiation. In this study, we present the first high-resolution, three-dimensional (3D) reconstructions of branching archaeocyathide (Order Archaeocyathida) individuals from three localities on the Laurentian paleocontinent. Because branched forms in sponges and corals display phenotypic plasticity that preserve the characteristics of the surrounding growth environment, we compare morphological measurements from our fossil specimens to those of modern corals to infer the surface conditions of Earth's first reefs. These data demonstrate that archaeocyaths could withstand and influence the flow of water, accommodate photosymbionts, and build topographically complex and stable structures much like corals today. We also recognize a stepwise increase in the roughness of reef environments in the lower Cambrian, which would have laid a foundation for more abundant and diverse coevolving fauna.</p>","PeriodicalId":173,"journal":{"name":"Geobiology","volume":"21 1","pages":"66-85"},"PeriodicalIF":3.7,"publicationDate":"2022-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5813419","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":"Endospores associated with deep seabed geofluid features in the eastern Gulf of Mexico","authors":"Jayne E. Rattray,&nbsp;Anirban Chakraborty,&nbsp;Gretta Elizondo,&nbsp;Emily Ellefson,&nbsp;Bernie Bernard,&nbsp;James Brooks,&nbsp;Casey R. J. Hubert","doi":"10.1111/gbi.12517","DOIUrl":"https://doi.org/10.1111/gbi.12517","url":null,"abstract":"<p>Recent studies have reported up to 1.9 × 10²⁹ bacterial endospores in the upper kilometre of deep subseafloor marine sediments, however, little is understood about their origin and dispersal. In cold ocean environments, the presence of thermospores (endospores produced by thermophilic bacteria) suggests that distribution is governed by passive migration from warm anoxic sources possibly facilitated by geofluid flow, such as advective hydrocarbon seepage sourced from petroleum deposits deeper in the subsurface. This study assesses this hypothesis by measuring endospore abundance and distribution across 60 sites in Eastern Gulf of Mexico (EGM) sediments using a combination of the endospore biomarker 2,6-pyridine dicarboxylic acid or ‘dipicolinic acid’ (DPA), sequencing 16S rRNA genes of thermospores germinated in 50°C sediment incubations, petroleum geochemistry in the sediments and acoustic seabed data from sub-bottom profiling. High endospore abundance is associated with geologically active conduit features (mud volcanoes, pockmarks, escarpments and fault systems), consistent with subsurface fluid flow dispersing endospores from deep warm sources up into the cold ocean. Thermospores identified at conduit sites were most closely related to bacteria associated with the deep biosphere habitats including hydrocarbon systems. The high endospore abundance at geological seep features demonstrated here suggests that recalcitrant endospores and their chemical components (such as DPA) can be used in concert with geochemical and geophysical analyses to locate discharging seafloor features. This multiproxy approach can be used to better understand patterns of advective fluid flow in regions with complex geology like the EGM basin.</p>","PeriodicalId":173,"journal":{"name":"Geobiology","volume":"20 6","pages":"823-836"},"PeriodicalIF":3.7,"publicationDate":"2022-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/gbi.12517","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5979732","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":"The deposition and significance of an Ediacaran non-glacial iron formation","authors":"Xiuqing Yang,&nbsp;Jingwen Mao,&nbsp;Rongxi Li,&nbsp;Zongsheng Jiang,&nbsp;Miao Yu,&nbsp;Lingang Xu,&nbsp;Tom Reershemius,&nbsp;Noah J. Planavsky","doi":"10.1111/gbi.12518","DOIUrl":"https://doi.org/10.1111/gbi.12518","url":null,"abstract":"<p>Most Neoproterozoic iron formations (NIF) are closely associated with global or near-global “Snowball Earth” glaciations. Increasingly, however, studies indicate that some NIFs show no robust evidence of glacial association. Many aspects of non-glacial NIF genesis, including the paleo-environmental setting, Fe(II) source, and oxidation mechanisms, are poorly understood. Here, we present a detailed case study of the Jiapigou NIF, a major non-glacial NIF within a Neoproterozoic volcano-sedimentary sequence in North Qilian, northwestern China. New U–Pb geochronological data place the depositional age of the Jiapigou NIF at ~600 Ma. Petrographic and geochemical evidence supports its identification as a primary chemical sediment with significant detrital input. Major and trace element concentrations, REE + Y systematics, and ε_Nd(t) values indicate that iron was sourced from mixed seawater and hydrothermal fluids. Iron isotopic values (δ⁵⁶Fe = −0.04‰–1.43‰) are indicative of partial oxidation of an Fe(II) reservoir. We infer that the Jiapigou NIF was deposited in a redox stratified water column, where hydrothermally sourced Fe(II)-rich fluids underwent oxidation under suboxic conditions. Lastly, the Jiapigou NIF has strong phosphorous enrichments, which in other iron formations are typically interpreted as signals for high marine phosphate concentrations. This suggests that oceanic phosphorus concentrations could have been enriched throughout the Neoproterozoic, as opposed to simply during glacial intervals.</p>","PeriodicalId":173,"journal":{"name":"Geobiology","volume":"21 1","pages":"44-65"},"PeriodicalIF":3.7,"publicationDate":"2022-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"6217269","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":"Nitrogen-based symbioses, phosphorus availability, and accounting for a modern world more productive than the Paleozoic","authors":"C. Kevin Boyce,&nbsp;Daniel E. Ibarra,&nbsp;Matthew P. Nelsen,&nbsp;Michael P. D'Antonio","doi":"10.1111/gbi.12519","DOIUrl":"https://doi.org/10.1111/gbi.12519","url":null,"abstract":"<p>Evolution of high-productivity angiosperms has been regarded as a driver of Mesozoic ecosystem restructuring. However, terrestrial productivity is limited by availability of rock-derived nutrients such as phosphorus for which permanent increases in weathering would violate mass balance requirements of the long-term carbon cycle. The potential reality of productivity increases sustained since the Mesozoic is supported here with documentation of a dramatic increase in the evolution of nitrogen-fixing or nitrogen-scavenging symbioses, including more than 100 lineages of ectomycorrhizal and lichen-forming fungi and plants with specialized microbial associations. Given this evidence of broadly increased nitrogen availability, we explore via carbon cycle modeling how enhanced phosphorus availability might be sustained without violating mass balance requirements. Volcanism is the dominant carbon input, dictating peaks in weathering outputs up to twice modern values. However, times of weathering rate suppression may be more important for setting system behavior, and the late Paleozoic was the only extended period over which rates are expected to have remained lower than modern. Modeling results are consistent with terrestrial organic matter deposition that accompanied Paleozoic vascular plant evolution having suppressed weathering fluxes by providing an alternative sink of atmospheric CO₂. Suppression would have then been progressively lifted as the crustal reservoir's holding capacity for terrestrial organic matter saturated back toward steady state with deposition of new organic matter balanced by erosion of older organic deposits. Although not an absolute increase, weathering fluxes returning to early Paleozoic conditions would represent a novel regime for the complex land biota that evolved in the interim. Volcanism-based peaks in Mesozoic weathering far surpass the modern rates that sustain a complex diversity of nitrogen-based symbioses; only in the late Paleozoic might these ecologies have been suppressed by significantly lower rates. Thus, angiosperms are posited to be another effect rather than proximal cause of Mesozoic upheaval.</p>","PeriodicalId":173,"journal":{"name":"Geobiology","volume":"21 1","pages":"86-101"},"PeriodicalIF":3.7,"publicationDate":"2022-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"6167147","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":"Low oxygen levels with high redox heterogeneity in the late Ediacaran shallow ocean: Constraints from I/(Ca + Mg) and Ce/Ce* of the Dengying Formation, South China","authors":"Yi Ding,&nbsp;Wei Sun,&nbsp;Shugen Liu,&nbsp;Jirong Xie,&nbsp;Dongjie Tang,&nbsp;Xiqiang Zhou,&nbsp;Limin Zhou,&nbsp;Zhiwu Li,&nbsp;Jinmin Song,&nbsp;Zeqi Li,&nbsp;Hongyuan Xu,&nbsp;Pan Tang,&nbsp;Kang Liu,&nbsp;Wenjun Li,&nbsp;Daizhao Chen","doi":"10.1111/gbi.12520","DOIUrl":"https://doi.org/10.1111/gbi.12520","url":null,"abstract":"<p>Most previous studies focused on the redox state of the deep water, leading to an incomplete understanding of the spatiotemporal evolution of the redox-stratified ocean during the Ediacaran–Cambrian transition. In order to decode the redox condition of shallow marine environments during the late Ediacaran, this study presents I/(Ca + Mg), carbon and oxygen isotope, major, trace, and rare earth element data of subtidal to peritidal dolomite from the Dengying Formation at Yangba, South China. In combination with the reported radiometric and biostratigraphic data, the Dengying Formation and coeval successions worldwide are subdivided into a positive δ¹³C excursion (up to ~6‰) in the lower part (~551–547 Ma) and a stable δ¹³C plateau (generally between 0‰ and 3‰) in the middle-upper part (~547–541 Ma). The overall low I/(Ca + Mg) ratios (&lt;0.5 μmol/mol) and slightly negative to no Ce anomalies (0.80 &lt; [Ce/Ce*]_SN &lt; 1.25), point to low-oxygen levels in shallow marine environments at Yangba. Moreover, four pulsed negative excursions in (Ce/Ce*)_SN (between 0.62 and 0.8) and the associated two positive excursions in I/(Ca + Mg) ratios (up to 2.02 μmol/mol) are observed, indicative of weak oxygenations in the shallow marine environments. The comparison with other upper Ediacaran shallow water successions worldwide reveals that the (Ce/Ce*)_SN and I/(Ca + Mg) values generally fall in the Precambrian range but their temporal trends differ among these successions (e.g., Ce anomaly profiles significantly different between Yangba and the Yangtze Gorge sections), which point to low oxygen levels with high redox heterogeneity in the surface ocean. This is consistent with the widespread anoxia as revealed by low δ²³⁸U values reported by previous studies. Thus, the atmospheric oxygen concentrations during the late Ediacaran are estimated to be very low, similar to the case during the most Mesoproterozoic to early Neoproterozoic period.</p>","PeriodicalId":173,"journal":{"name":"Geobiology","volume":"20 6","pages":"790-809"},"PeriodicalIF":3.7,"publicationDate":"2022-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"6162676","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":"Interplay between abiotic and microbial biofilm-mediated processes for travertine formation: Insights from a thermal spring (Piscine Carletti, Viterbo, Italy)","authors":"Stefania Venturi,&nbsp;Simona Crognale,&nbsp;Francesco Di Benedetto,&nbsp;Giordano Montegrossi,&nbsp;Barbara Casentini,&nbsp;Stefano Amalfitano,&nbsp;Tommaso Baroni,&nbsp;Simona Rossetti,&nbsp;Franco Tassi,&nbsp;Francesco Capecchiacci,&nbsp;Orlando Vaselli,&nbsp;Stefano Fazi","doi":"10.1111/gbi.12516","DOIUrl":"https://doi.org/10.1111/gbi.12516","url":null,"abstract":"<p>Active hydrothermal travertine systems are ideal environments to investigate how abiotic and biotic processes affect mineralization mechanisms and mineral fabric formation. In this study, a biogeochemical characterization of waters, dissolved gases, and microbial mats was performed together with a mineralogical investigation on travertine encrustations occurring at the outflow channel of a thermal spring. The comprehensive model, compiled by means of TOUGHREACT computational tool from measured parameters, revealed that mineral phases were differently influenced by either abiotic conditions or microbially driven processes. Microbial mats are shaped by light availability and temperature gradient of waters flowing along the channel. Mineralogical features were homogeneous throughout the system, with euhedral calcite crystals, related to inorganic precipitation induced by CO₂ degassing, and calcite shrubs associated with organomineralization processes, thus indicating an indirect microbial participation to the mineral deposition (microbially influenced calcite). The microbial activity played a role in driving calcite redissolution processes, resulting in circular pits on calcite crystal surfaces possibly related to the metabolic activity of sulfur-oxidizing bacteria found at a high relative abundance within the biofilm community. Sulfur oxidation might also explain the occurrence of gypsum crystals embedded in microbial mats, since gypsum precipitation could be induced by a local increase in sulfate concentration mediated by S-oxidizing bacteria, regardless of the overall undersaturated environmental conditions. Moreover, the absence of gypsum dissolution suggested the capability of microbial biofilm in modulating the mobility of chemical species by providing a protective envelope on gypsum crystals.</p>","PeriodicalId":173,"journal":{"name":"Geobiology","volume":"20 6","pages":"837-856"},"PeriodicalIF":3.7,"publicationDate":"2022-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"6039390","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":"On the trail of iron uptake in ancestral Cyanobacteria on early Earth","authors":"Tristan C. Enzingmüller-Bleyl,&nbsp;Joanne S. Boden,&nbsp;Achim J. Herrmann,&nbsp;Katharina W. Ebel,&nbsp;Patricia Sánchez-Baracaldo,&nbsp;Nicole Frankenberg-Dinkel,&nbsp;Michelle M. Gehringer","doi":"10.1111/gbi.12515","DOIUrl":"https://doi.org/10.1111/gbi.12515","url":null,"abstract":"<p>Cyanobacteria oxygenated Earth's atmosphere ~2.4 billion years ago, during the Great Oxygenation Event (GOE), through oxygenic photosynthesis. Their high iron requirement was presumably met by high levels of Fe(II) in the anoxic Archean environment. We <i>found that</i> many deeply branching Cyanobacteria, including two <i>Gloeobacter</i> and four <i>Pseudanabaena</i> spp., cannot synthesize the Fe(II) specific transporter, FeoB. Phylogenetic and relaxed molecular clock analyses find evidence that FeoB and the Fe(III) transporters, cFTR1 and FutB, were present in Proterozoic, but not earlier Archaean lineages of Cyanobacteria. Furthermore <i>Pseudanabaena</i> sp. PCC7367, an early diverging marine, benthic strain grown under simulated Archean conditions, constitutively expressed <i>cftr1</i>, even after the addition of Fe(II). Our genetic profiling suggests that, prior to the GOE, ancestral Cyanobacteria may have utilized alternative metal iron transporters such as ZIP, NRAMP, or FicI, and possibly also scavenged exogenous siderophore bound Fe(III), as they only acquired the necessary Fe(II) and Fe(III) transporters during the Proterozoic. Given that Cyanobacteria arose 3.3–3.6 billion years ago, it is possible that limitations in iron uptake may have contributed to the delay in their expansion during the Archean, and hence the oxygenation of the early Earth.</p>","PeriodicalId":173,"journal":{"name":"Geobiology","volume":"20 6","pages":"776-789"},"PeriodicalIF":3.7,"publicationDate":"2022-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/gbi.12515","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5926108","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}