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

TL;DR

Two new bacterial species and a genome-based reorganization of the genus Coprococcus are proposed based on strains isolated from human feces.

Contribution

The paper introduces two novel bacterial species and reclassifies several species within the genus Coprococcus using genomic data.

Findings

Strains OB7620T and OB7656T represent two new species, Allocoprococcus similis and Faecalimonas hominis.

Genomic analysis led to the reclassification of Coprococcus comes into a new genus, Allocoprococcus.

Coprococcus immobilis and Coprococcus catus are reclassified into the new genus Pseudocoprococcus.

Abstract

The obligately anaerobic, Gram-stain-positive coccobacilli strains OB7620T and OB7656T were isolated from faecal samples of healthy Japanese volunteers. Strain OB7620T showed the highest 16S rRNA gene sequence similarity to Coprococcus comes ATCC 27758T (98.4%) and Clostridium nexile DSM 1787T (96.3%). Strain OB7656T showed the highest 16S rRNA gene sequence similarity to ‘Gluceribacter canis’ NATH-2371T (97.7%), C. nexile DSM 1787T (94.8%) and Faecalimonas umbilicata EGH7T (94.8%). These findings indicate that the two strains represent novel species. Genomic analysis clarified the phylogenetic relationship of C. comes with the species cluster designated as Coprococcus sensu stricto, which includes the type species, C. eutactus. As C. comes is distinct from the species of Coprococcus sensu stricto, C. comes is reclassified into a novel genus, Allocoprococcus, as Allocoprococcus comes gen. nov., comb. nov. Although strain OB7620T is closely related to C. comes, it is a distinct species. Therefore, we propose the name Allocoprococcus similis gen. nov., sp. nov. The type strain is OB7620T (=DSM 118890T=JCM 37173T). Because Coprococcus catus differs from Coprococcus sensu stricto, it has been placed in a novel genus, Pseudocoprococcus, as Pseudocoprococcus catus gen. nov., comb. nov. We also concluded that Coprococcus immobilis and Coprococcus intestinihominis are the same species and belong to the new genus Pseudocoprococcus. As C. immobilis has priority, we propose the name Pseudocoprococcus immobilis gen. nov., comb. nov. We also concluded that C. nexile and Clostridium phoceensis are the same species in the genus Faecalimonas. As C. nexile has priority, we propose the name Faecalimonas nexilis comb. nov. Coprococcus mobilis and ‘G. canis’ should also be reclassified within the genus Faecalimonas. Therefore, we propose the name Faecalimonas mobilis comb. nov. and Faecalimonas canis sp. nov. As strain OB7656T is related to ‘G. canis’ but is a different species, we propose the name Faecalimonas hominis sp. nov. The type strain is OB7656T (=DSM 118889T=JCM 37172T).

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