التفاصيل البيبلوغرافية
| العنوان: |
Energetically Informed Niche Models of Hydrogenotrophs Detected in Sediments of Serpentinized Fluids of the Samail Ophiolite of Oman. |
| المؤلفون: |
Howells, Alta E. G., Leong, James A. M., Ely, Tucker, Santana, Michelle, Robinson, Kirt, Esquivel‐Elizondo, Sofia, Cox, Alysia, Poret‐Peterson, Amisha, Krajmalnik‐Brown, Rosa, Shock, Everett L. |
| المصدر: |
Journal of Geophysical Research. Biogeosciences; Mar2022, Vol. 127 Issue 3, p1-30, 30p |
| مصطلحات موضوعية: |
FLUIDS, ELECTROPHILES, THRESHOLD energy, CHEMICAL energy, SEDIMENTS, RESERVOIR sedimentation, BIOTIC communities |
| مصطلحات جغرافية: |
OMAN |
| مستخلص: |
A geochemical gradient established by mixing between reduced, hyperalkaline (pH > 11), H2‐rich fluids generated through the process of serpentinization and surrounding surface water (pH ∼ 8) in the Samail Ophiolite of Oman provides an opportunity to characterize the geochemical and biological factors that influence the distribution of H2 oxidizing chemotrophs, hydrogenotrophs. In this study, 16S rRNA gene amplicon sequencing was implemented to characterize hydrogenotrophs in sediments underlying surface expressed serpentinized fluids in Oman. Hydrogenotroph phylotype distribution was evaluated as functions of chemical energy supplies for their given metabolic redox reactions. Through this approach, it was discovered that hydrogenotrophic taxa are likely constrained to sediments with overlying fluids that have <∼60 μm O2, including microorganisms of the genus, Hydrogenophaga. Sulfate reducers of the family, Thermodesulfovibrionaceae, likely require >∼10 μm SO4−2 for survival. In sediments with fluids having >∼10 μm SO4−2, sulfate reducers likely outcompete microorganisms of the methanogen genus, Methanobacterium, for H2. Additionally, differences in distribution between Thermodesulfovibrionaceae and Methanobacterium may be driven by the availability of electron acceptors and the redox reaction that is most energy yielding in the fluid. Taken together, observations from the Oman geochemical gradient result in a hydrogenotroph niche model that can be used to evaluate global distribution patterns of hydrogenotrophs in continental serpentinized fluids. On a global scale, based on previous studies, Methanobacterium is constrained to fluids that have <∼10 μm SO4−2. Plain Language Summary: A subsurface geological process called serpentinization produces H2 as a result of reduced rock from the upper mantle reacting with water. Microbial hydrogenotrophs can tap into this geological supply of H2 and oxidize it for energy. Hydrogenotrophic community composition varies in serpentinization‐hosted ecosystems across the globe. To determine geochemical and biological factors that may influence hydrogenotroph community composition, we evaluated the correspondence between the distribution of hydrogenotrophs among pools of serpentinized fluid in Oman and the chemical energy supplies used by their metabolisms. In doing so we discovered that sulfate reducers and methanogens (that reduce CO2 to CH4 by oxidizing H2) are differentially distributed. We attribute this difference in distribution to variation in the availability of their respective electron acceptors. Additionally, we discovered that O2, known to be toxic to hydrogenotrophs like sulfate reducers and methanogens, may constrain the hydrogenotrophs of this study to systems that are relatively O2 poor (<60 μm). Finally, in comparing hydrogenotroph distribution to chemical energy supply, we were able to characterize environmental thresholds for energy and substrates, below which survival may be limited. In all, this study provides a framework for assessing factors that may influence hydrogenotroph distribution in serpentinization‐hosted systems across the globe. Key Points: Hydrogenotroph distribution indicates O2 concentrations >60 micromolality are likely toxic to serpentinized fluid hydrogenotrophsElectron acceptor availability in serpentinized fluids likely drives the lack of co‐existence between sulfate reducer and methanogensThe energy threshold of serpentinized fluid methanogens is comparable to the energy required to convert 1 mol ADP to 1 mol ATP [ABSTRACT FROM AUTHOR] |
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