Bifidobacterium kashiwanohense sp. nov., isolated from healthy infant faeces

Abstract

Strains HM2-1 and HM2-2T were isolated from the faeces of a healthy infant and were characterized by determining their phenotypic and biochemical features and phylogenetic positions based on partial 16S rRNA gene sequence analysis. They were Gram-positive, obligately anaerobic, non-spore-forming, non-gas-producing, and catalase-negative non-motile rods. They did not grow at 15 or 45 °C in anaerobic bacterial culture medium, and their DNA G+C content was in the range 56–59 mol%. In enzyme activity tests, strains HM2-1 and HM2-2T were positive for α/β-galactosidases and α/β-glucosidases but negative for β-glucuronidase and cystine arylamidase. An analysis of the cell-wall composition of strains HM2-1 and HM2-2T revealed the presence of glutamic acid, alanine and lysine. The presence of fructose-6-phosphate phosphoketolase shows that isolates HM2-1 and HM2-2T are members of the genus Bifidobacterium. These two isolates belong to the same species of the genus Bifidobacterium. Strain HM2-2T was found to be related to Bifidobacterium catenulatum JCM 1194T (97.4 % 16S rRNA gene sequence identity: 1480/1520 bp), Bifidobacterium pseudocatenulatum JCM 1200T (97.2 %: 1472/1514 bp), Bifidobacterium dentium ATCC 27534T (96.7 %: 1459/1509 bp) and Bifidobacterium angulatum ATCC 27535T (96.5 %: 1462/1515 bp). The predominant cellular fatty acids of strains HM2-1 and HM2-2T were 16 : 0 and 18 : 1ω9c, with proportions greater than 18 % of the total. Phylogenetic analyses involving phenotypic characterization, DNA–DNA hybridization and partial 16S rRNA gene sequencing proves that the strains represent a novel species of the genus Bifidobacterium, for which the name Bifidobacterium kashiwanohense sp. nov. is proposed. The type strain is HM2-2T ( = JCM 15439T  = DSM 21854T).