Occurrence of methane-oxidizing bacteria and methanogenic archaea in earth’s cave systems—A metagenomic analysis

Karst ecosystems represent up to 25% of the land surface and recent studies highlight their potential role as a sink for atmospheric methane. Despite this, there is limited knowledge diversity distribution methane-oxidizing bacteria (MOB) or methanogens in karst caves sub-surface environment general. Here, we performed survey 14 shotgun metagenomes from cave covering broad set environmental conditions, compare relative abundance phylogenetic MOB methanogens, targeting biomarker genes methane monooxygenase ( pmoA mmoX ) methyl-coenzyme M reductase mcrA ). Taxonomic analysis showed 0.02–1.28% classified reads were related known MOB, which Gammaproteobacterial most abundant making on average 70% surveyed caves’ community. Potential biogenic production was also observed, with 0.008–0.39% dominated by sequences Methanosarcina . We have generated protein database (CEPD) based level assembly that can be used profile interest.