Parabacteroides johnsonii sp. nov., isolated from human faeces

Abstract

A bacterial strain isolated from human faeces, M-165T, was characterized in terms of its phenotypic and biochemical features, cellular fatty acid profile, menaquinone profile and phylogenetic position (based on 16S rRNA gene sequence analysis). A 16S rRNA gene sequence analysis showed that the isolate was a member of the genusParabacteroides. Strain M-165Twas closely related toParabacteroides merdaestrains, showing 98 % sequence similarity. The strain was obligately anaerobic, non-pigmented, non-spore-forming, non-motile, Gram-negative, rod-shaped and was able to grow on media containing 20 % bile. Although the phenotypic characteristics of the strain M-165Twere similar to those ofP. merdae, the isolate could be differentiated fromP. merdaeby means of API 20A tests forl-arabinose andl-rhamnose fermentation. DNA–DNA hybridization experiments revealed the genomic distinctiveness of the novel strain with respect toP. merdaeJCM 9497T(⩽60 % DNA–DNA relatedness). The DNA G+C content of the strain is 47.6 mol%. On the basis of these data, strain M-165Trepresents a novel species of the genusParabacteroides, for which the nameParabacteroides johnsoniisp. nov. is proposed. The type strain is M-165T(=JCM 13406T=DSM 18315T).