Northern palsa and peat ecosystem microbiomes are potentially supported by hydrogen and carbon monoxide metabolism

Abstract

Northern peatland and permafrost ecosystems are facing rapid changes, with increasing temperatures, permafrost thaw and shifts in hydrology. Characterizing microbial communities and metabolic potential from the soils and associated water bodies is crucial to understanding the changes in biogeochemical cycling in these ecosystems. For this, samples were collected and sequenced from subarctic palsa and peat soils, along with samples from associated thaw ponds and streams. Metagenomics was utilized in describing the microbiome and its metabolic potential in these environments. Palsa soils hosted microbial communities that were distinct from the peatland soils, ponds and stream waters. Soils and their adjacent ponds shared taxa, and peat soils and ponds also shared taxa with the streams, unlike palsa soils which were likely more hydrologically isolated. Based on metabolic marker gene ratio for denitrification [(nirS+nirK)/nosZ], palsa soils had the strongest potential to be a source of nitrous oxide (N2O) out of all the sample types. Marker genes for hydrogen gas (H2) and carbon monoxide (CO) utilization were abundant across soil environments and metagenome assembled genomes, suggesting that trace gas oxidation is likely one of the key energy sources for microbiomes. In the palsa ponds and peat soils pmoA, marker gene for methanotrophy, was the most abundant compared to the other sample types.