New species (and genus) belonging to Cloacimonadota

Bacteria associated with this genus belong to the Cloacimonadota phylum and have been found mainly in anaerobic digestion systems so far.

Cloacimonas fortuita was co-isolated from an enrichment culture of a methanogenic reactor containing anaerobic wastewater sludge, alongside its archaeal syntrophic partner Methanothrix and other minor bacterial species. The genome of this species is 1.98 Mb in length, with a GC content of 36.6%, and encodes 1591 genes, including 1529 protein-coding genes. Based on the functional annotation, it is presumed to perform syntrophic propionate oxidation via an alternative pathway. Genome of this species and its relative C. acidaminovorans have an Average Nucleotide Identity of 78.3%, which is below the species-level cut-off (95%) but above the genus-level threshold (>70%). Therefore, we would like to claim a new species within the known Cloacimonas genus.

The genome of Digestoria delfossei in OTU_1 is complete and closed, 2.3 Mbp long, with a GC content of 54.3%, and it contains two rRNA operons. The species represents a distinct lineage defined by ANI ≥ 95% to its known relatives. Therefore, only the novel genus and species are formally established, while all higher‑level ranks remain unnamed pending further phylogenomic resolution of the phylum. D. delfossei encodes a complete glycolysis pathway with exception for pyruvate kinase, previously shown to be replaced by pyruvate orthophosphate dikinase in Cloacimonadota genomes, and the microorganism can oxidize pyruvate further to acetyl-CoA and acetate. It is capable of beta-oxidation and protein degradation (i.e., encoding multiple peptidases) with a complete metabolism of histidine to glutamate.