Subsurface Microbial Communities Utilise a Wide Range of Aromatic Compounds in Anoxic Coal Seams

Abstract

Summary Coal bed methane is a key source of energy in the transition from fossil fuels to renewables. Although a large proportion of this methane is generated via subsurface biological processes, little is known about the degradation pathways and microbial communities responsible. Previous literature has identified many of the microbial communities present in methane-producing coal seams and speculated as to which of these microbes are responsible for possible coal-to-methane degradation processes in situ. Anoxic microcosms were established with a range of different monoaromatic and polyaromatic compounds as sole sources of carbon. These microcosms were inoculated with a coal seam microbial community sourced from a methane-producing well in the Surat Basin, Queensland, Australia. After incubation, community amplicon sequencing of the 16S rRNA gene revealed the identities of microbes that increased in relative abundance on each of the aromatic substrates. Putative degradation pathways for the substrates were hypothesized, along with which microbes are likely to be active in different parts of the degradation pathways, based on both these analyses and pre-existing literature on anaerobic degradation of aromatic compounds from non-coal environments. This research provides valuable insights into the catabolism of organic matter in coal in situ.