MULTI-OMIC SEQUENCING OF THE COAL BED MICROBIOME: ACTIVE MICROBES AND PATHWAYS DURING ENHANCED METHANOGENESIS (Invited Presentation)

The recalcitrant nature of coal limits the rate of biogenic coalbed methane production, as it is difficult to biodegrade the complex structure of coal into methanogenic substrates. Beyond the identification of many organic intermediates (e.g., dissolved organic carbon), the coupling between the biological decomposition of coal and methane production remains unknown. High-throughput sequencing technologies (metagenomics and metatranscriptomics) allow for the identification of specific microbial phylogenies and the functional genes that are actively utilized in the coal bed microbiome. The USGS has an established field site (Birney test site) where organic nutrients and deuterated water were injected to attempt to enhance and isotopically label methane generated post-injection in the Flowers-Goodale coal bed, Powder River Basin, USA. To retrieve a representative coal-associated microbial community, a subsurface environmental sampler was used to collect in situ samples for metagenomic and metatranscriptomic analysis from three hydrologically connected wells at the test site before and after the injection. Initial analysis indicates the microbial community shifted following the injection and the expression of genes related to a specific acetoclastic methanogen (Methanothrix) increased. Specific hydrocarbon degradation and acetate formation metabolic pathways were investigated that could be involved in the conversion of coal to methane. Results provide insight into active metabolic strategies used by subsurface microorganisms to overcome the potential rate-limiting step in the bioconversion of complex subsurface carbon to methane.