High-latitude environments are disproportionately impacted by anthropogenic climate change, leading to rapid permafrost thaw and increased greenhouse gas emissions. Soil microbiota have been shown to contribute significantly to increased methane and carbon dioxide emissions from these thawing permafrost ecosystems. However, in spite of large viral impacts on microbial dynamics and metabolic outputs in other environments (e.g., the oceans), viral impacts on soil microbes and ecosystems are virtually unknown. We analyzed 201 bulk soil metagenomes along an Arctic permafrost thaw gradient to identify viral populations as a basis for developing an ecological understanding of viruses in these ecosystems.
A total of 1,907 viral genomes and large genome fragments were recovered, approximately doubling known prokaryotic soil viral genera. Viral community composition differed along the thaw gradient, concomitant with shifts in host community composition and biogeochemistry. In silico host prediction linked 35% of the viruses to co-occurring host populations, including biogeochemically relevant microbes such as methanogens and methanotrophs. These linkages enabled lineage-specific virus:host abundance estimates, which revealed dynamic infections of different host lineages across the permafrost thaw gradient tied to carbon chemistry. Together, these data suggest that viruses are integral to modulating climate-critical peatland soil biogeochemistry.