Dr. Kelly Wrighton from the Ohio State University, Department of Microbiology will present a seminar titled:
Life in the deep shale biosphere: What goes down, may come up
Hydraulic fracturing, colloquially known as “fracking”, is employed for effective gas and oil recovery in deep black shales. This process injects organisms and liquids from the surface into the deep subsurface (~2500 m), exposing microorganisms to high pressures, elevated temperatures, chemical additives, and brine-level salinities. In this talk, I will discuss our use of assembly-based metagenomics to create a metabolic blueprint from energy-producing Marcellus shale over a 328-day period. Using this approach we ask the question: What abiotic and biotic factors drive microbial metabolism and thus biogeochemical cycling during natural gas extraction? We found that after 49 days, increased salinity in produced waters corresponded to a shift in the microbial community, with only organisms that encode salinity adaptations detected. We posit that organic compatible solutes produced by organisms to adapt to salinity fuels a methylamine driven ecosystem in fractured shale. This metabolic network ultimately results in biogenic methane production from members of Methanohalophilus and Methanolobus. Proton NMR validated these genomic hypotheses, with monomethylamines detected 328 days after fracking. Beyond abiotic constraints, our genomic investigations revealed that viruses can be linked to key members of the microbial community, potentially releasing methylamine substrates and impacting bacterial strain variation of the system. Collectively our genomic results indicate that adaptation to high salinity, metabolism in the absence of oxidized electron acceptors, and viral predation are controlling factors mediating microbial community metabolism during hydraulic fracturing of the deep subsurface.