Proposal of two novel species, Allocoprococcus similis gen. nov., sp. nov. and Faecalimonas hominis sp. nov., isolated from human faeces and genome-based reorganization of the genus Coprococcus

The obligately anaerobic, Gram-stain-positive coccobacilli strains OB7620^T and OB7656^T were isolated from faecal samples of healthy Japanese volunteers. Strain OB7620^T showed the highest 16S rRNA gene sequence similarity to <i>Coprococcus comes</i> ATCC 27758^T (98.4%) and <i>Clostridium nexile</i> DSM 1787^T (96.3%). Strain OB7656^T showed the highest 16S rRNA gene sequence similarity to '<i>Gluceribacter canis</i>' NATH-2371^T (97.7%), <i>C. nexile</i> DSM 1787^T (94.8%) and <i>Faecalimonas umbilicata</i> EGH7^T (94.8%). These findings indicate that the two strains represent novel species. Genomic analysis clarified the phylogenetic relationship of <i>C. comes</i> with the species cluster designated as <i>Coprococcus sensu stricto</i>, which includes the type species, <i>C. eutactus</i>. As <i>C. comes</i> is distinct from the species of <i>Coprococcus sensu stricto</i>, <i>C. comes</i> is reclassified into a novel genus, <i>Allocoprococcus</i>, as <i>Allocoprococcus comes</i> gen. nov., comb. nov. Although strain OB7620^T is closely related to <i>C. comes</i>, it is a distinct species. Therefore, we propose the name <i>Allocoprococcus similis</i> gen. nov., sp. nov. The type strain is OB7620^T (=DSM 118890^T=JCM 37173^T). Because <i>Coprococcus catus</i> differs from <i>Coprococcus sensu stricto</i>, it has been placed in a novel genus, <i>Pseudocoprococcus</i>, as <i>Pseudocoprococcus catus</i> gen. nov., comb. nov. We also concluded that <i>Coprococcus immobilis</i> and <i>Coprococcus intestinihominis</i> are the same species and belong to the new genus <i>Pseudocoprococcus</i>. As <i>C. immobilis</i> has priority, we propose the name <i>Pseudocoprococcus immobilis</i> gen. nov., comb. nov. We also concluded that <i>C. nexile</i> and <i>Clostridium phoceensis</i> are the same species in the genus <i>Faecalimonas</i>. As <i>C. nexile</i> has priority, we propose the name <i>Faecalimonas nexilis</i> comb. nov. <i>Coprococcus mobilis</i> and '<i>G. canis</i>' should also be reclassified within the genus <i>Faecalimonas</i>. Therefore, we propose the name <i>Faecalimonas mobilis</i> comb. nov. and <i>Faecalimonas canis</i> sp. nov. As strain OB7656^T is related to '<i>G. canis</i>' but is a different species, we propose the name <i>Faecalimonas hominis</i> sp. nov. The type strain is OB7656^T (=DSM 118889^T=JCM 37172^T).