Dataset Information

Versatile cyanobacteria control the timing and extent of sulfide production in a Proterozoic analog microbial mat.

ABSTRACT: Cyanobacterial mats were hotspots of biogeochemical cycling during the Precambrian. However, mechanisms that controlled O₂ release by these ecosystems are poorly understood. In an analog to Proterozoic coastal ecosystems, the Frasassi sulfidic springs mats, we studied the regulation of oxygenic and sulfide-driven anoxygenic photosynthesis (OP and AP) in versatile cyanobacteria, and interactions with sulfur reducing bacteria (SRB). Using microsensors and stable isotope probing we found that dissolved organic carbon (DOC) released by OP fuels sulfide production, likely by a specialized SRB population. Increased sulfide fluxes were only stimulated after the cyanobacteria switched from AP to OP. O₂ production triggered migration of large sulfur-oxidizing bacteria from the surface to underneath the cyanobacterial layer. The resultant sulfide shield tempered AP and allowed OP to occur for a longer duration over a diel cycle. The lack of cyanobacterial DOC supply to SRB during AP therefore maximized O₂ export. This mechanism is unique to benthic ecosystems because transitions between metabolisms occur on the same time scale as solute transport to functionally distinct layers, with the rearrangement of the system by migration of microorganisms exaggerating the effect. Overall, cyanobacterial versatility disrupts the synergistic relationship between sulfide production and AP, and thus enhances diel O₂ production.

SUBMITTER: Klatt JM

PROVIDER: S-EPMC7784965 | biostudies-literature | 2020 Dec

REPOSITORIES: biostudies-literature

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Versatile cyanobacteria control the timing and extent of sulfide production in a Proterozoic analog microbial mat.

Klatt Judith M JM Gomez-Saez Gonzalo V GV Meyer Steffi S Ristova Petra Pop PP Yilmaz Pelin P Granitsiotis Michael S MS Macalady Jennifer L JL Lavik Gaute G Polerecky Lubos L Bühring Solveig I SI

The ISME journal 20200807 12

Cyanobacterial mats were hotspots of biogeochemical cycling during the Precambrian. However, mechanisms that controlled O<sub>2</sub> release by these ecosystems are poorly understood. In an analog to Proterozoic coastal ecosystems, the Frasassi sulfidic springs mats, we studied the regulation of oxygenic and sulfide-driven anoxygenic photosynthesis (OP and AP) in versatile cyanobacteria, and interactions with sulfur reducing bacteria (SRB). Using microsensors and stable isotope probing we found ...[more]

PMID: 32770117

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Project description:Shale gas production fluids offer a window into the engineered deep biosphere. Here, for the first time, we report on the geochemistry and microbiology of production fluids from a UK shale gas well in the Bowland shale formation. The composition of input fluids used to fracture this well were comparatively lean, consisting only of water, sand, and polyacrylamide. This formation therefore represents an interesting comparison to previously explored fractured shales in which more additives were used in the input fluids. Here, we combine cultivation and molecular ecology techniques to explore the microbial community composition of hydraulic fracturing production fluids, with a focus on the potential for common viscosity modifiers to stimulate microbial growth and biogenic sulfide production. Production fluids from a Bowland Shale exploratory well were used as inocula in substrate utilization experiments to test the potential for polyacrylamide and guar gum to stimulate microbial metabolism. We identified a consortium of thiosulfate-reducing bacteria capable of utilizing guar gum (but not polyacrylamide), resulting in the production of corrosive and toxic hydrogen sulfide. Results from this study indicate polyacrylamide is less likely than guar gum to stimulate biogenic sulfide production during shale gas extraction and may guide planning of future hydraulic fracturing operations. IMPORTANCE Shale gas exploitation relies on hydraulic fracturing, which often involves a range of chemical additives in the injection fluid. However, relatively little is known about how these additives influence fractured shale microbial communities. This work offers a first look into the microbial community composition of shale gas production fluids obtained from an exploratory well in the Bowland Shale, United Kingdom. It also seeks to establish the impact of two commonly used viscosity modifiers, polyacrylamide and guar gum, on microbial community dynamics and the potential for microbial sulfide production. Not only does this work offer fascinating insights into the engineered deep biosphere, it could also help guide future hydraulic fracturing operations that seek to minimize the risk of biogenic sulfide production, which could reduce efficiency and increase environmental impacts of shale gas extraction.

Dataset Information

Versatile cyanobacteria control the timing and extent of sulfide production in a Proterozoic analog microbial mat.

Publications

Versatile cyanobacteria control the timing and extent of sulfide production in a Proterozoic analog microbial mat.

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