Butyricimonas faecihominis sp. nov. and Butyricimonas paravirosa sp. nov., isolated from human faeces, and emended description of the genus Butyricimonas

Two bacterial strains, designated 180-3T and 214-4T, isolated from human faeces were characterized by using a polyphasic taxonomic approach that included analysis of their phenotypic and biochemical features, cellular fatty acid profiles, menaquinone profiles and phylogenetic positions based on 16S rRNA gene sequence analysis. 16S rRNA gene sequence analysis showed that these strains represented members of the genus Butyricimonas. These strains shared 97.9 % 16S rRNA gene sequence similarity with each other and were related to Butyricimonas virosa JCM 15149T (97 % sequence similarity) and Butyricimonas synergistica JCM 15148T (94–95 %). Although strain 180-3T was related to (but distinct from) B. virosa JCM 15149T and B. synergistica JCM 15148T, with hsp60 gene sequence similarities of 89.4 and 84.6 %, respectively, strain 214-4T exhibited high hsp60 gene sequence similarity (100 %) with B. virosa JCM 15149T and was different from B. synergistica JCM 15148T (83.5 %). DNA–DNA hybridization experiments demonstrated a genomic distinction of strains 180-3T and 214-4T from B. virosa JCM 15149T and B. synergistica JCM 15148T. The strains were obligately anaerobic, non-pigmented, non-spore-forming, non-motile, Gram-stain-negative rods. Growth of the strains was inhibited on medium containing 20 % bile. The two strains produced butyric and isobutyric acids as the end products from glucose, as has been observed in the other two species of the genus Butyricimonas. The major cellular fatty acid of strains 180-3T and 214-4T was iso-C15 : 0. The major menaquinone of the isolates was MK-10 (>50 %). Strains 180-3T and 214-4T have DNA G+C contents of 45 mol%. On the basis of these data, strains 180-3T and 214-4T represent two novel species of the genus Butyricimonas, for which the names Butyricimonas faecihominis sp. nov. and Butyricimonas paravirosa sp. nov., respectively, are proposed. The type strains of B. faecihominis and B. paravirosa are 180-3T ( = JCM 18676T = CCUG 65562T) and 214-4T ( = JCM 18677T = CCUG 65563T), respectively.