Jayne E. Rattray, Anirban Chakraborty, Gretta Elizondo, Emily Ellefson, Bernie Bernard, James Brooks, Casey R. J. Hubert
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.
{"title":"Endospores associated with deep seabed geofluid features in the eastern Gulf of Mexico","authors":"Jayne E. Rattray, Anirban Chakraborty, Gretta Elizondo, Emily Ellefson, Bernie Bernard, James Brooks, 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 × 10<sup>29</sup> 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":null,"pages":null},"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}
Xiuqing Yang, Jingwen Mao, Rongxi Li, Zongsheng Jiang, Miao Yu, Lingang Xu, Tom Reershemius, Noah J. Planavsky
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 εNd(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.
{"title":"The deposition and significance of an Ediacaran non-glacial iron formation","authors":"Xiuqing Yang, Jingwen Mao, Rongxi Li, Zongsheng Jiang, Miao Yu, Lingang Xu, Tom Reershemius, 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<sub>Nd</sub>(t) values indicate that iron was sourced from mixed seawater and hydrothermal fluids. Iron isotopic values (δ<sup>56</sup>Fe = −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":null,"pages":null},"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}
C. Kevin Boyce, Daniel E. Ibarra, Matthew P. Nelsen, Michael P. D'Antonio
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.
{"title":"Nitrogen-based symbioses, phosphorus availability, and accounting for a modern world more productive than the Paleozoic","authors":"C. Kevin Boyce, Daniel E. Ibarra, Matthew P. Nelsen, 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 CO<sub>2</sub>. 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":null,"pages":null},"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}
Yi Ding, Wei Sun, Shugen Liu, Jirong Xie, Dongjie Tang, Xiqiang Zhou, Limin Zhou, Zhiwu Li, Jinmin Song, Zeqi Li, Hongyuan Xu, Pan Tang, Kang Liu, Wenjun Li, Daizhao Chen
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 (<0.5 μmol/mol) and slightly negative to no Ce anomalies (0.80 < [Ce/Ce*]SN < 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.
{"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, Wei Sun, Shugen Liu, Jirong Xie, Dongjie Tang, Xiqiang Zhou, Limin Zhou, Zhiwu Li, Jinmin Song, Zeqi Li, Hongyuan Xu, Pan Tang, Kang Liu, Wenjun Li, 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 δ<sup>13</sup>C excursion (up to ~6‰) in the lower part (~551–547 Ma) and a stable δ<sup>13</sup>C plateau (generally between 0‰ and 3‰) in the middle-upper part (~547–541 Ma). The overall low I/(Ca + Mg) ratios (<0.5 μmol/mol) and slightly negative to no Ce anomalies (0.80 < [Ce/Ce*]<sub>SN</sub> < 1.25), point to low-oxygen levels in shallow marine environments at Yangba. Moreover, four pulsed negative excursions in (Ce/Ce*)<sub>SN</sub> (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*)<sub>SN</sub> 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 δ<sup>238</sup>U 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":null,"pages":null},"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}
Stefania Venturi, Simona Crognale, Francesco Di Benedetto, Giordano Montegrossi, Barbara Casentini, Stefano Amalfitano, Tommaso Baroni, Simona Rossetti, Franco Tassi, Francesco Capecchiacci, Orlando Vaselli, Stefano Fazi
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.
{"title":"Interplay between abiotic and microbial biofilm-mediated processes for travertine formation: Insights from a thermal spring (Piscine Carletti, Viterbo, Italy)","authors":"Stefania Venturi, Simona Crognale, Francesco Di Benedetto, Giordano Montegrossi, Barbara Casentini, Stefano Amalfitano, Tommaso Baroni, Simona Rossetti, Franco Tassi, Francesco Capecchiacci, Orlando Vaselli, 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 CO<sub>2</sub> 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":null,"pages":null},"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}
Tristan C. Enzingmüller-Bleyl, Joanne S. Boden, Achim J. Herrmann, Katharina W. Ebel, Patricia Sánchez-Baracaldo, Nicole Frankenberg-Dinkel, Michelle M. Gehringer
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 found that many deeply branching Cyanobacteria, including two Gloeobacter and four Pseudanabaena 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 Pseudanabaena sp. PCC7367, an early diverging marine, benthic strain grown under simulated Archean conditions, constitutively expressed cftr1, 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.
{"title":"On the trail of iron uptake in ancestral Cyanobacteria on early Earth","authors":"Tristan C. Enzingmüller-Bleyl, Joanne S. Boden, Achim J. Herrmann, Katharina W. Ebel, Patricia Sánchez-Baracaldo, Nicole Frankenberg-Dinkel, 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":null,"pages":null},"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}
Heidi S. Aronson, Danielle R. Monteverde, Ben Davis Barnes, Brooke R. Johnson, Mike J. Zawaski, Daan R. Speth, Xingchen Tony Wang, Fenfang Wu, Samuel M. Webb, Elizabeth J. Trower, John S. Magyar, Alex L. Sessions, Victoria J. Orphan, Geobiology Course 2017, Geobiology Course 2018, Woodward W. Fischer
Biogeochemical cycling of sulfur is relatively understudied in terrestrial environments compared to marine environments. However, the comparative ease of access, observation, and sampling of terrestrial settings can expand our understanding of organisms and processes important in the modern sulfur cycle. Furthermore, these sites may allow for the discovery of useful process analogs for ancient sulfur-metabolizing microbial communities at times in Earth's past when atmospheric O2 concentrations were lower and sulfide was more prevalent in Earth surface environments. We identified a new site at Santa Paula Creek (SPC) in Ventura County, CA—a remarkable freshwater, gravel-bedded mountain stream charged with a range of oxidized and reduced sulfur species and heavy hydrocarbons from the emergence of subsurface fluids within the underlying sulfur- and organic-rich Miocene-age Monterey Formation. SPC hosts a suite of morphologically distinct microbial biofacies that form in association with the naturally occurring hydrocarbon seeps and sulfur springs. We characterized the geology, stream geochemistry, and microbial facies and diversity of the Santa Paula Creek ecosystem. Using geochemical analyses and 16S rRNA gene sequencing, we found that SPC supports a dynamic sulfur cycle that is largely driven by sulfide-oxidizing microbial taxa, with contributions from smaller populations of sulfate-reducing and sulfur-disproportionating taxa. This preliminary characterization of SPC revealed an intriguing site in which to study geological and geochemical controls on microbial community composition and to expand our understanding of sulfur cycling in terrestrial environments.
与海洋环境相比,陆地环境中硫的生物地球化学循环研究相对较少。然而,相对容易获得、观察和取样的陆地环境可以扩大我们对现代硫循环中重要的生物和过程的理解。此外,这些地点可能允许发现古代硫代谢微生物群落的有用过程类似物,在地球过去的某些时候,大气中O2浓度较低,硫化物在地球表面环境中更为普遍。我们在加州文图拉县的Santa Paula Creek (SPC)找到了一个新的地点,这是一条淡水、砾石层状的山间溪流,富含一系列氧化和还原硫物质,以及来自富含硫和有机物的中新世蒙特雷组地下流体的重碳氢化合物。SPC拥有一套形态独特的微生物相,这些微生物相与自然发生的碳氢化合物渗漏和硫泉有关。我们描述了Santa Paula Creek生态系统的地质、河流地球化学、微生物相和多样性。通过地球化学分析和16S rRNA基因测序,我们发现SPC支持一个动态硫循环,该循环主要由硫化物氧化微生物类群驱动,较小的硫酸盐还原和硫歧化类群也有贡献。SPC的初步特征揭示了一个有趣的研究地点,可以研究微生物群落组成的地质和地球化学控制,并扩大我们对陆地环境中硫循环的理解。
{"title":"Sulfur cycling at natural hydrocarbon and sulfur seeps in Santa Paula Creek, CA","authors":"Heidi S. Aronson, Danielle R. Monteverde, Ben Davis Barnes, Brooke R. Johnson, Mike J. Zawaski, Daan R. Speth, Xingchen Tony Wang, Fenfang Wu, Samuel M. Webb, Elizabeth J. Trower, John S. Magyar, Alex L. Sessions, Victoria J. Orphan, Geobiology Course 2017, Geobiology Course 2018, Woodward W. Fischer","doi":"10.1111/gbi.12512","DOIUrl":"https://doi.org/10.1111/gbi.12512","url":null,"abstract":"<p>Biogeochemical cycling of sulfur is relatively understudied in terrestrial environments compared to marine environments. However, the comparative ease of access, observation, and sampling of terrestrial settings can expand our understanding of organisms and processes important in the modern sulfur cycle. Furthermore, these sites may allow for the discovery of useful process analogs for ancient sulfur-metabolizing microbial communities at times in Earth's past when atmospheric O<sub>2</sub> concentrations were lower and sulfide was more prevalent in Earth surface environments. We identified a new site at Santa Paula Creek (SPC) in Ventura County, CA—a remarkable freshwater, gravel-bedded mountain stream charged with a range of oxidized and reduced sulfur species and heavy hydrocarbons from the emergence of subsurface fluids within the underlying sulfur- and organic-rich Miocene-age Monterey Formation. SPC hosts a suite of morphologically distinct microbial biofacies that form in association with the naturally occurring hydrocarbon seeps and sulfur springs. We characterized the geology, stream geochemistry, and microbial facies and diversity of the Santa Paula Creek ecosystem. Using geochemical analyses and 16S rRNA gene sequencing, we found that SPC supports a dynamic sulfur cycle that is largely driven by sulfide-oxidizing microbial taxa, with contributions from smaller populations of sulfate-reducing and sulfur-disproportionating taxa. This preliminary characterization of SPC revealed an intriguing site in which to study geological and geochemical controls on microbial community composition and to expand our understanding of sulfur cycling in terrestrial environments.</p>","PeriodicalId":173,"journal":{"name":"Geobiology","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2022-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5849244","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}
Mingfei Chen, Jessica L. Conroy, Emily C. Geyman, Robert A. Sanford, Joanne C. Chee-Sanford, Lynn M. Connor
Marine and lacustrine carbonate minerals preserve carbon cycle information, and their stable carbon isotope values (δ13C) are frequently used to infer and reconstruct paleoenvironmental changes. However, multiple processes can influence the δ13C 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 δ13C values of syndepositional carbonate grains of varying morphologies to investigate their origins. Here, we combine stable isotope analyses, metagenomics, and geochemical modeling to interpret δ13C 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 δ13C 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 δ13C 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 δ13C values. The down-core spherule–micrite offset in δ13C values also aligns with total organic carbon values, suggesting that the difference in the δ13C values of spherules and micrite may be a more robust, inorganic indicator of variability in productivity and local biological processes through time than the δ13C values of individual carbonate forms.
{"title":"Stable carbon isotope values of syndepositional carbonate spherules and micrite record spatial and temporal changes in photosynthesis intensity","authors":"Mingfei Chen, Jessica L. Conroy, Emily C. Geyman, Robert A. Sanford, Joanne C. Chee-Sanford, Lynn M. Connor","doi":"10.1111/gbi.12509","DOIUrl":"https://doi.org/10.1111/gbi.12509","url":null,"abstract":"<p>Marine and lacustrine carbonate minerals preserve carbon cycle information, and their stable carbon isotope values (δ<sup>13</sup>C) are frequently used to infer and reconstruct paleoenvironmental changes. However, multiple processes can influence the δ<sup>13</sup>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 δ<sup>13</sup>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 δ<sup>13</sup>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 <i>in situ</i> with minor diagenetic alterations. The δ<sup>13</sup>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 δ<sup>13</sup>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 δ<sup>13</sup>C values. The down-core spherule–micrite offset in δ<sup>13</sup>C values also aligns with total organic carbon values, suggesting that the difference in the δ<sup>13</sup>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 δ<sup>13</sup>C values of individual carbonate forms.</p>","PeriodicalId":173,"journal":{"name":"Geobiology","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2022-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/gbi.12509","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5918362","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}
Chlorine has important roles in the Earth's systems. In different forms, it helps balance the charge and osmotic potential of cells, provides energy for microorganisms, mobilizes metals in geologic fluids, alters the salinity of waters, and degrades atmospheric ozone. Despite this importance, there has not been a comprehensive summary of chlorine's geobiology. Here, we unite different areas of recent research to describe a biogeochemical cycle for chlorine. Chlorine enters the biosphere through volcanism and weathering of rocks and is sequestered by subduction and the formation of evaporite sediments from inland seas. In the biosphere, chlorine is converted between solid, dissolved, and gaseous states and in oxidation states ranging from −1 to +7, with the soluble, reduced chloride ion as its most common form. Living organisms and chemical reactions change chlorine's form through oxidation and reduction and the addition and removal of chlorine from organic molecules. Chlorine can be transported through the atmosphere, and the highest oxidation states of chlorine are produced by reactions between sunlight and trace chlorine gases. Partial oxidation of chlorine occurs across the biosphere and creates reactive chlorine species that contribute to the oxidative stress experienced by living cells. A unified view of this chlorine cycle demonstrates connections between chlorine biology, chemistry, and geology that affect life on the Earth.
{"title":"The biogeochemical cycling of chlorine","authors":"Tyler P. Barnum, John D. Coates","doi":"10.1111/gbi.12513","DOIUrl":"https://doi.org/10.1111/gbi.12513","url":null,"abstract":"<p>Chlorine has important roles in the Earth's systems. In different forms, it helps balance the charge and osmotic potential of cells, provides energy for microorganisms, mobilizes metals in geologic fluids, alters the salinity of waters, and degrades atmospheric ozone. Despite this importance, there has not been a comprehensive summary of chlorine's geobiology. Here, we unite different areas of recent research to describe a biogeochemical cycle for chlorine. Chlorine enters the biosphere through volcanism and weathering of rocks and is sequestered by subduction and the formation of evaporite sediments from inland seas. In the biosphere, chlorine is converted between solid, dissolved, and gaseous states and in oxidation states ranging from −1 to +7, with the soluble, reduced chloride ion as its most common form. Living organisms and chemical reactions change chlorine's form through oxidation and reduction and the addition and removal of chlorine from organic molecules. Chlorine can be transported through the atmosphere, and the highest oxidation states of chlorine are produced by reactions between sunlight and trace chlorine gases. Partial oxidation of chlorine occurs across the biosphere and creates reactive chlorine species that contribute to the oxidative stress experienced by living cells. A unified view of this chlorine cycle demonstrates connections between chlorine biology, chemistry, and geology that affect life on the Earth.</p>","PeriodicalId":173,"journal":{"name":"Geobiology","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2022-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5745707","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}
Protection from radiation damage is an important adaptation for phototrophic microbes. Living in surface, shallow water, and peritidal environments, cyanobacteria are especially exposed to long-wavelength ultraviolet (UVA) radiation. Several groups of cyanobacteria within these environments are protected from UVA damage by the production of the pigment scytonemin. Paleontological evidence of cyanobacteria in UVA-exposed environments from the Proterozoic, and possibly as early as the Archaean, suggests a long evolutionary history of radiation protection within this group. We show that phylogenetic analyses of enzymes in the scytonemin biosynthesis pathway support this hypothesis and reveal a deep history of vertical inheritance of this pathway within extant cyanobacterial diversity. Referencing this phylogeny to cyanobacterial molecular clocks suggests that scytonemin production likely appeared during the early Proterozoic, soon after the Great Oxygenation Event. This timing is consistent with an adaptive scenario for the evolution of scytonemin production, wherein the threat of UVA-generated reactive oxygen species becomes significantly greater once molecular oxygen is more pervasive across photosynthetic environments.
{"title":"Inferred ancestry of scytonemin biosynthesis proteins in cyanobacteria indicates a response to Paleoproterozoic oxygenation","authors":"Erik Tamre, Gregory P. Fournier","doi":"10.1111/gbi.12514","DOIUrl":"https://doi.org/10.1111/gbi.12514","url":null,"abstract":"<p>Protection from radiation damage is an important adaptation for phototrophic microbes. Living in surface, shallow water, and peritidal environments, cyanobacteria are especially exposed to long-wavelength ultraviolet (UVA) radiation. Several groups of cyanobacteria within these environments are protected from UVA damage by the production of the pigment scytonemin. Paleontological evidence of cyanobacteria in UVA-exposed environments from the Proterozoic, and possibly as early as the Archaean, suggests a long evolutionary history of radiation protection within this group. We show that phylogenetic analyses of enzymes in the scytonemin biosynthesis pathway support this hypothesis and reveal a deep history of vertical inheritance of this pathway within extant cyanobacterial diversity. Referencing this phylogeny to cyanobacterial molecular clocks suggests that scytonemin production likely appeared during the early Proterozoic, soon after the Great Oxygenation Event. This timing is consistent with an adaptive scenario for the evolution of scytonemin production, wherein the threat of UVA-generated reactive oxygen species becomes significantly greater once molecular oxygen is more pervasive across photosynthetic environments.</p>","PeriodicalId":173,"journal":{"name":"Geobiology","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2022-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/gbi.12514","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5918361","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}