Global terrestrial distribution of N2O-reducing Acidobacteriota members.

Nitrous oxide (N2O) is a potent greenhouse gas, and soil is its largest terrestrial source. Microbial N2O reductase (NosZ) is the only known enzyme capable of reducing N2O to N2, making nosZ-harboring prokaryotes important sinks in terrestrial ecosystems. Despite being among the most abundant and ubiquitous bacterial phyla in soil, the potential role of Acidobacteriota in N2O reduction remains largely unexplored. In this study, we addressed this gap using genomic, metagenomic, and physiological analyses. We first analyzed 199,602  prokaryotic genomes, including genomes from both isolated strains and metagenome-assembled genomes (MAGs). We found that 491 Acidobacteriota genomes harbored nosZ, predominantly the Sec-dependent NosZ gene (nosZII). Global metagenomic analysis of 321 soil samples revealed that Acidobacteriota nosZII is one of the most abundant groups of nosZ and distributed across different continents. Among Acidobacteriota, nosZII from the class Vicinamibacteria was the most prevalent in the soils. Finally, we provide the physiological evidence of N2O-reducing activity in Acidobacteriota by demonstrating that the Vicinamibacteria type strain, Luteitalea pratensis KCTC52215T, can reduce N2O. Taken together, these findings highlight the previously overlooked potential role of Acidobacteriota as a global N2O sink and underscore the need to include them in future studies on soil N2O dynamics.