Indigenous life in extreme environments: Characterizing pristine shale rock hosted biomass

Abstract

The terrestrial subsurface is estimated to be the largest global reservoir of bacterial and archaeal biomass, but few studies have been performed in this environment due to technical challenges and costs associated with sample recovery. This study seeks to characterize the diversity and distribution of microbial life in the Marcellus shale formation and their associated interfaces within the Appalachian Basin, and to investigate the potential impact of these organisms on hydrocarbon reservoirs and extraction techniques. Pristine sidewall cores from the Marcellus shale and associated formations were collected as part of the Marcellus Shale Energy and Environment Laboratory (MSEEL) research effort. We decontaminated the outer surfaces of the cores and used the resulting ground material to inoculate a variety of cultivation experiments. These assays, operated under atmospheric and high-pressure conditions, were designed to enrich for metabolisms potentially occurring in deep subsurface shale. Due to the low biomass within these formations, single-cell genomics are being utilized to characterize the cultivated microorganisms from pristine shale. Through previous preliminary experimentation with a Halanaerobium isolate obtained from hydraulic fracturing produced fluids, we have optimized methods for desorbing biomass from shale surfaces. Microbial populations enriched in the presence of sulfate and methylamines in pristine shales have been submitted for single cell genomic analyses. Future tasks include quantification and sorting of the shale derived cells using flow cytometry, followed by genomic DNA sequencing from individual cells. Data from these investigations will reveal adaptations and new metabolisms of these indigenous organisms persisting in this extreme shale environment. This study is the first of its kind to investigate the role of indigenous microbial life in the Appalachian basin, and will provide insight into the role of deep subsurface organisms and how they may influence hydrocarbon extraction techniques.

AAPG Datapages/Search and Discovery Article #90258 © 2016 AAPG Eastern Section Meeting, Lexington, Kentucky, September 25-27, 2016