Sulfur cycling in UK fractured shale microbial communities under elevated pressure
Hydraulic fracturing creates engineered subsurface environments in which microbial activity can influence geochemistry, infrastructure integrity, and hydrocarbon production. This study investigated sulfidogenic microbial communities from UK Bowland Shale flowback fluids and shale core under simulated subsurface conditions. Six high-pressure bioreactors containing sand and ground Bowland Shale were operated for 25 weeks at 30 degrees Celsius and 6.9 MPa. Three reactors were inoculated with enriched Bowland-1 flowback fluids, while three uninoculated reactors served as controls. Weekly injection of anaerobic saline medium containing thiosulfate and guar gum enabled assessment of sulfur cycling, polymer utilisation, and microbial community succession.