Metagenomic insights into microbial structure and metabolism in alpine permafrost on the Tibetan Plateau

Permafrost, characterized by its frozen soil, serves as a unique and ecologically significant habitat for diverse microorganisms. Understanding the intricacies of their community structure and functional attributes is crucial for predicting the response of permafrost ecosystems to climate change. However, large-scale evidence regarding microbial profiles and their differences across soil strata remains limited. Here we analyze microbial structure and metabolic potential in permafrost deposits based on 16S rRNA and metagenomic data obtained from a ∼1,000 km permafrost transect on the Tibetan Plateau. We find that microbial communities exhibit apparent discrepancy in structure among soil depth, with a decline in alpha diversity and an increase in spatial variation along soil profile. Microbial assemblages are primarily governed by dispersal limitation and drift, with dispersal limitation being more pronounced in permafrost layer. We also observe that functional genes related to reduction reactions, including nitrate reduction, denitrification, polysulfide reduction, sulfide reduction, tetrathionate reduction, Fe reduction, and methanogenesis, are enriched in the permafrost layer. Taxa involving in redox reactions are more diverse in the permafrost layer and contribute highly to community-level metabolic profiles, reflecting higher redox potential and more complicated trophic strategies for microorganisms in permafrost deposits. These findings provide new insights into the large-scale stratigraphic profiles of microbial community structure and biogeochemical processes and laying the groundwork for future endeavors that elucidate microbial responses to environmental change in permafrost regions.