Disko methane-cycling microbiome

The methane-cycling microbiomes in Arctic permafrost-affected upland soils play crucial roles in the production and consumption of this important greenhouse gas. However, little is known about the distributions of Arctic methanogens and methanotrophs across the regional scale and along the vertical soil profile, respectively. Using a unique sample set from eight different locations across the pan-Arctic we screened for methanogen and methanotroph phylotypes in 621 datasets of 16S rRNA gene amplicons. Only 22 methanogen and 26 methanotroph phylotypes were identified in 621 upland soil samples. Relative abundances of both groups varied significantly between sites and soil horizons. Water content was not correlated with methanotroph abundance, but both were positively correlated with methanogen abundance. This suggested that water content might control methanogen abundance, which in turn drove methanotroph abundance by providing the substrate. Only four methanogen phylotypes were detected at all locations, with the hydrogenotrophic Methanobacterium lacus dominating. Remarkably, the methane filter was almost exclusively comprised of a few phylotypes closely related to the obligate methanotrophic bacterium Methylobacter tundripaludum SV96. This study provides first insights into the identity and intricate spatial distribution of methanotrophs and methanogens in permafrost soils at a pan-Arctic scale, and points towards a few key microbes particularly relevant for future studies due to permafrost thaw.