Drivers of Microbial Community Development and Persistence in Deep Subsurface Shales
EMSL Project ID
50132
Abstract
Hydraulic fracturing, the extraction of oil and gas from deep shale reservoirs via high-pressure injection of fluids, is now a critical part of the US energy portfolio. Microbial communities inadvertently introduced during the fracking process converge in this subsurface ecosystem to a terminal population dominated by halophilic, fermentative microorganisms. While the activity of such microorganisms is generally considered to be deleterious (e.g., corrosion, bio-clogging), our research team has previously documented the potential for new biogenic methane production by these terminal communities, offering a possibility for extending the life of these wells and increasing natural gas reserves. Despite these impacts, little is known about how different strains and taxa interact within the framework of the microbial community. We propose a series of studies to understand the environmental selection pressures that constrain microbial populations in this new subsurface ecosystem characterized by high pressures and increasing salinity. Leveraging extensive genomic and geochemical datasets developed by our research group from hydraulically fractured wells, we will initially identify mechanisms that support strain-level heterogeneity within the population, and enable microorganisms to persist in the deep subsurface. This approach will use high-resolution metabolite and proteomic analyses available at EMSL. Given that our preliminary data has indicated a highly active role for viruses in this ecosystem, we will then determine the role of viral lysis in both constraining strain-level population dynamics and releasing intracellular compounds to sustain microbial communities. We hypothesize that the viral-mediated release of intracellular contents may offer a mechanism to sustain microbial populations over extended periods of time (> 200 days). Nuclear magnetic resonance (NMR) will be used to track viral activity and metabolite pools during these experiments. Due to the genomic tractability of these systems, coupled with our extensive metadata (time-resolved geochemistry, microbial isolates), deep shale ecosystems represent an outstanding opportunity to study linked carbon cycling and controls on microbial community development. This proposed work therefore addresses key EMSL and DOE focus areas that aim to better understand geochemical and biological processes driving C dynamics in subsurface environments. Given the paucity of data related to both pristine and fractured shale environments, we posit that this proposed research is critical for informing the scientific community, industry, and the general public.
Project Details
Start Date
2018-01-22
End Date
2018-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Related Publications
Booker A.E., E.K. Eder, A.R. Wong, D.W. Hoyt, and M.J. Wilkins. 06/22/2019. "Deep Subsurface Pressure Stimulates Metabolic Versatility in Shale-Colonizing Halanaerobium." Abstract submitted to American Society for Microbiology Conference, San Francisco, California. PNNL-SA-140940.