Structure and function of the global peatland microbiome

Peatlands are vital long-term carbon sinks but can also be greenhouse gas sources, with the balance largely governed by microbial processes. However, the structure and function of peatland microbial communities are currently poorly characterised at the global scale, limiting our understanding of their response to climate change. Here, we present a global analysis of the peatland microbiome by leveraging a dataset of 109 publicly available metagenomes from 20 near-natural peatland sites worldwide. We identify dominant vegetation and peatland type as the strongest predictors of peatland microbiome taxonomy and function. Different peatland types host distinct microbiomes, with implications for the main microbial processes in these ecosystems. We reveal a high metabolic potential of the northern bog microbiome for plant organic matter degradation, largely attributed to Acidobacteriota. Moreover, we show that the tropical peatland microbiome exhibits a broad metabolic potential for key peatland biogeochemical processes, including methanogenesis and denitrification, across all depths. Intriguingly, we observe an impaired potential for complete denitrification in a significant proportion of the northern fen metagenomes, providing implications for nitrous oxide emissions as a greenhouse gas. Overall, our study provides key insights into the global patterns and ecological drivers of the peatland microbiome, enhancing our understanding of their response to climate change.