Methanotroph-derived bacteriohopanepolyol signatures in sediments covering Miocene brown coal deposits

Methanotrophic bacteria (MB) are an important group of microorganisms, involved in the greenhouse gas (GHG) cycles. They are responsible for the utilization of methane, one of the main GHGs, which is released in large amounts (via biogenic and abiogenic processes) during coal formation. This study aimed to determine the main factors affecting the distribution of the MB in two lignite-bearing series of the Tur ' ow and Belchat ' ow coal basins. Distribution of MB in the lignite profiles was studied using methanotroph-specific lipid biomarkers such as amino-bacteriohopanepolyols (NH-BHPs) and C-3 methylated BHPs. BHP results were combined with physical and chemical properties of the studied sediments. In general, lignites were richer in BHPs than the mineral samples, which points to the important role of the intrinsic methane cycling. NH-BHP speciation confirmed that the methanotrophic community of the studied sediments was a combination of both type I and, especially, type II methanotrophs. Based on geological data, it was suggested that elevated temperature during diagenesis intensifies decomposition of methanotroph-specific biomarkers (aminopentol and 3-Me BHT). It was found that the tested BHPs can derive from both fossil and living MB. The presence of metabolically active methanotrophs should therefore be accounted for during studies aimed at using lignite deposits as a source of methane.

Automated summary

Methanotrophic bacteria play a crucial role in methane utilization and are influenced by factors like temperature during diagenesis. The study used lipid biomarkers to examine the distribution of MB in lignite-bearing series and identified both fossil and living MB contributing to methane cycling. The presence of a diverse methanotrophic community in sediments suggests the need to consider active methanotrophs when utilizing lignite deposits for methane extraction.