Background While oligotrophic bacteria are known to dominate most marine microbial habitats, under certain conditions, such as during phytoplankton blooms, copiotrophs can dramatically increase in abu...

Background The candidate phyla radiation (CPR) comprises a widespread but poorly understood group of bacteria with limited cultured representatives, largely due to their metabolic dependencies on micr...

Candidatus Acidulodesulfobacterales, a formerly proposed bacterial order within the Deltaproteobacteria lineage, represents an ecologically significant group in sulfur-rich environments. Their diversity and functional potential in artificial acid mine drainage (AMD) ecosystems have been well studied; however, their distribution and ecological role in marine hydrothermal sulfides remain poorly understood. Here we integrated publicly available metagenome-assembled genomes (MAGs) with a newly reconstructed MAG from hydrothermal sulfides to perform comprehensive phylogenetic, metabolic, and host-virus interaction analyses. Phylogenomic and 16S rRNA gene analyses indicated that this lineage represents a distinct phylum-level clade, leading us to propose the designation Ca. Acidulodesulfobacteriota. Metabolic reconstructions indicated a versatile lifestyle, encompassing pathways for carbon fixation, nitrogen fixation, sulfur metabolism, iron oxidation, and hydrogen oxidation. Notably, the concatenated DsrAB protein phylogeny and the mixed enzyme types involved in Dsr-dependent dissimilatory sulfur metabolism suggest that Ca. Acidulodesulfobacteriota may represent a transitional lineage in the evolutionary shift from reductive to oxidative Dsr metabolism. Viral auxiliary metabolic genes (AMGs) associated with this phylum were predicted to modulate host metabolic pathways, including folate biosynthesis and sulfur metabolism, highlighting intricate host-virus interactions. These findings advance our understanding of the evolution, metabolic potential, and ecological roles of Ca. Acidulodesulfobacteriota in biogeochemical cycling.

In the field of public health, we conduct a variety of experiments and studies on insects, such as mosquitoes, to advance vector-borne disease research. However entomologists’ variable knowledge and a...