Microbial Community Shifts on Organic Rocks of Different Maturities Reveal potential Catabolisers of Organic Matter in Coal

Abstract

The global trend of transiting to more renewable energy sources requires transition fuels, such as coal seam gas, to supplement and secure energy needs. In order to optimise strategies and technologies for enhancing gas production, an understanding of the fundamental microbial processes and interactions would be advantageous. Models have recently begun mapping the microbial roles and interactions in coal seam environments, from direct coal degradation to methanogenesis. This study seeks to expand those models by observing community compositional shifts in the presence of differing organic matter by conducting 16S rRNA microbial surveys using formation water from the Surat and Sydney Basins grown on varying types of organic matter (black and brown coal, oil shale, humic acid, and lignin). A total of 135 microbes were observed to become enriched in the presence of added organic matter in comparison to carbon-free treatments. These surveys allowed detailed analysis of microbial compositions in order to extrapolate which taxa favour growth in the presence of differing organic matter. This study has experimentally demonstrated shifts in the microbial community composition due to differing carbon sources and, for the first time, generated a conceptual model to map putative degradation pathways regarding subsurface microbial consortia.