Clostridium hiranonis sp nov., a human intestinal bacterium with bile acid 7α-dehydroxylating activity

The Clostridium-like organisms TO-931(T) and HD-17, isolated from human faeces, have high levels of bile acid 7 alpha -dehydroxylating activity. Sequencing of their 16S rDNA demonstrated that they belong to cluster XI of the genus Clostridium and that they represent a new and distinct line of descent. Clostridium bifermentans and Clostridium sordellii in cluster XI also possess bile acid 7 alpha -dehydroxylating activity. DNA-DNA hybridization experiments with the isolates, TO-931(T) and HD-17, and C. bifermentans and C. sordellii revealed that the isolates are a single species distinct from C. bifermentans and C. sordellii. On the basis of phylogenetic analysis, using 16S rDNA sequences, and DNA-DNA hybridization analysis, it is concluded that strains TO-931T and HD-17 are members of a new species of the genus Clostridium, for which the name Clostridium hiranonis is proposed. The type strain is strain TO-931(T) (= JCM 10541(T) = DSM 13275(T)).