Six strains of Gram-stain-negative, obligately anaerobic, non-spore-forming, non-motile rods were isolated from human faeces. Based on phylogenetic characteristics, the six isolates were included in the family Ruminococcaceae, and divided into three groups. The six isolates showed 16S rRNA gene sequence similarity values lower than 96.2 % to the closely related species, Oscillibacter ruminantium GH1T, Oscillibacter valericigenes Sjm18-20T and Dysosmobacter welbiomis J115T. Coherently with the 16S rRNA gene sequence results, the in silico DNA-DNA hybridization and average nucleotide identity values clearly indicated that strains MM35T, MM50T and MM59T belong to different species from the closely related three species. Based on phenotypic features and phylogenetic positions, three novel species, Vescimonas coprocola gen. nov., sp. nov., Vescimonas fastidiosa gen. nov., sp. nov. and Pusillimonas faecalis gen. nov., sp. nov. are proposed. The type strain of V. coprocola is strain MM50T (=JCM 34012T=DSM 111893T). The type strain of V. fastidiosa is strain MM35T (=JCM 34016T=DSM 111899T). The type strain of P. faecalis is strain MM59T (=JCM 34011T=DSM 111669T). The DNA G+C contents estimated according to the whole genomes of strains MM35T, MM50T and MM59T were 56.4, 58.2 and 55.2 mol%, respectively.
Keywords: Oscillibacter; human faeces; human intestinal microbiota.