Assignment of Eubacterium sp VPI 12708 and related strains with high bile acid 7α-dehydroxylating activity to Clostridium scindens and proposal of Clostridium hylemonae sp nov., isolated from human faeces

Unknown Eubacterium-like organisms VPI 12708 and five strains (Y-1113, 1-10, M-18, TH-82 and 36S) had high bile acid 7 alpha-dehydroxylating activity; the unknown Clostridium-like organisms TN-271(T) and TN-272 also had the same activity, Analysis of their 16S rDNA sequences demonstrated that all strains belong to cluster XIVa of the genus Clostridium (Collins et al,, 1994), Strain VPI 12708 and five other strains (Y-1113, I-10, M-18, TH-82 and 36S) formed a single cluster and strains TN-271(T) and TN-272 formed another single cluster. Clostridium scindens JCM 6567(T) was the most closely related species for two clusters in the phylogenetic tree. Values for DNA-DNA similarities among C. scindens JCM 6567(T), strain VPI 12708 and the other five strains were greater than 70%, showing that these micro-organisms were a single species. Therefore, we identified strain VPI 12708 and the five other strains as C. scindens, In addition, DNA-DNA similarities among C. scindens JCM 6567(T), strain TN-271(T) and strain N-272 revealed that strains TN-271(T) and TN-272 were distinct from C. scindens JCM 6567(T). con the basis of phylogenetic analysis and DNA-DNA similarity data, it was concluded that strains TN-271(T) and TN-272 are members of a new species of the genus Clostridium, for which the name Clostridium hylemonae is proposed. The type strain is strain TN-271(T) (= JCM 10539(T)).