Description of Catenibacterium mitsuokai subsp. tridentinum subsp. nov., an anaerobic bacterium isolated from human faeces, and emended description of C. mitsuokai

A recent metagenomic survey has revealed an unknown bacterial clade within the Catenibacterium mitsuokai species to be significantly more prevalent in non-urbanized populations, compared to urbanized ones. We isolated and characterized a strain of this clade from the stool of a healthy adult volunteer. Strain CMD8551T is strictly anaerobic, appears as long chains of Grampositive rods and produces acetate in the presence of glucose. The lipidomic profile showed a higher proportion of saturated lipid species amongst the detected phospholipids. The whole genome is 2,320,430 bp long and has a G+C content of 33.7 mol% with 2,239 CDSs. A phylogenetic analysis comparing the sequences of the strain CMD8551T with publicly available reference genomes from the Catenibacterium genus revealed that the CMD8551T isolate, together with other isolate genomes, forms a distinct subspecies of C. mitsuokai and has an average nucleotide identity lower than 94% with respect to the previously described C. mitsuokai subsp. mitsuokai. Given the phenotypic, chemotaxonomic and phylogenetic characteristics of the newly isolated CMD8551T (=DSM 118469T=LMG 33725T=CIP 112509T) that clearly differ from those of the C. mitsuokai subsp. mitsuokai type strain RCA14-39T, we propose it as the type strain of a novel subspecies of C. mitsuokai, with the name C. mitsuokai subsp. tridentinum subsp. nov.