Molecular Evidence for an Active Microbial Methane Cycle in Subsurface Serpentinite-Hosted Groundwaters in the Samail Ophiolite, Oman

Serpentinization of ultramafic rock can generate conditions favorable for microbial methane (CH 4 ) cycling, including the abiotic production hydrogen (H 2 and possibly CH . Systems low-temperature serpentinization are geobiological targets due to their potential harbor life ubiquity throughout Earth’s history. Biomass in fracture waters collected from Samail Ophiolite Oman, a system undergoing modern serpentinization, yielded DNA RNA signatures indicative active methanogenesis methanotrophy. Intriguingly, transcripts proteins involved were most abundant highly reacted that have hyperalkaline pH elevated concentrations H These findings suggest biological cycling serpentinite-hosted aquifers, even under extreme high carbon limitation. observations underscore activity influence isotopic composition these systems, which is information could help identifying biosignatures on other planets.