An analysis of the methane-producing microbial community in a coal bed of the Illinois Basin

Dariusz Strpo^*, Flynn W. Picardal, Courtney Turich, Irene Schaperdoth, Jennifer L. Macalady, Julius S. Lipp, Yu-Shih Lin, Tobias F. Ertefai, Florence Schubotz, Kai-Uwe Hinrichs, Maria Mastalerz, and Arndt Schimmelmann

Indiana University, Dept. of Geological Sciences, Bloomington, Indiana; Indiana University, School of Public and Environmental Affairs, Bloomington, Indiana; Penn State University, Dept. of Geosciences, University Park, Pennsylvania; Research Center Ocean Margins & Dept. of Geosciences, University of Bremen, Bremen, Germany; Indiana University, Indiana Geological Survey, Bloomington, Indiana

^* To whom correspondence should be addressed. Email: dariusz.strapoc{at}conocophillips.com.

	Abstract

A series of molecular and geochemical studies were performed to study biogenic, coalbed methane formation in the eastern Illinois Basin. Results suggest that organic matter is biodegraded to simple molecules, such as H₂ and CO₂, which fuel methanogenesis and the generation of large coalbed methane (CBM) reserves. Small subunit rRNA analysis of both the in-situ microbial community and highly-purified, methanogenic enrichments indicated that Methanocorpusculum is the dominant genus. Additionally, we characterized this methanogenic microorganism using scanning electron microscopy (SEM) and distribution of intact polar cell membrane lipids (IPLs). Phylogenetic studies of coal water samples helped us develop a model of methanogenic biodegradation of macromolecular coal and coal-derived oil by complex microbial community. Based on enrichments, phylogenetic analyses, and calculated free energies at in-situ subsurface conditions for relevant metabolisms (H₂-utilizing methanogenesis, acetoclastic methanogenesis, and homoacetogenesis), H₂-utilizing methanogenesis appears to be the dominant terminal process of biodegradation of coal organic matter at this location.