Abstract: Globally, the Acidobacteriota phylum is both extraordinarily widespread and abundant, serving indispensable roles in carbon, sulfur, and nutrient cycling. However, our comprehension is marked by a significant culture-based bias. Many of the newly reconstructed metagenome-assembled genomes (MAGs) represent uncultured lineages that remain substantially understudied, highlighting this gap. Concurrently, research on Acidobacteriota has been predominantly focused on soil environments, with a scarcity of studies in other environments. Here, we bridged this gap by compiling a genomic catalog of 4317 genomes. Protein content analysis, in conjunction with large-scale metabolic reconstructions, delineates seven genomic clusters of Acidobacteriota with unique metabolic profiles. Clusters 1 and 2 are soil-preferring, and clusters 3, 4, and 6 from various environments, exhibit diverse energy metabolism, including aerobic, facultatively anaerobic, anaerobic, and fermentative processes, and utilize a wide range of carbon substrates. Conversely, aquatic-preferring cluster 5 and various environments derived cluster 7 are strictly anaerobic, relying on nitrate/nitrite reduction or fermentation, and cluster 5 have a limited carbon utilization range. Our analyses have also identified previously unrecognized roles in C1 metabolic pathways, Calvin cycle, dissimilatory nitrate reduction to ammonium (DNRA), and denitrification among the uncultured Acidobacteriota, indicating that Acidobacteriota represent overlooked important function involved in methylotrophy, CO oxidation, carbon fixation and nitrogen cycling. These findings provide new insights into the metabolic diversity of Acidobacteriota, emphasizing their functional importance across diverse taxa and environments, and significantly expanding our understanding of these dominant yet understudied bacteria.

Key words: Acidobacteriota, carbon fixation, C1 metabolism, denitrification, dissimilatory nitrate reduction to ammonium, metabolic diversity