Fig. 1.

Phylogenetic tree of the genus Bifidobacterium based on the concatenation of the 169 amino acid sequences representing the Bifidobacterium core genome. The phylogenetic tree was generated by the maximum-likelihood method, and COG sequences of Scardovia inopinata JCM 12537 shared with bifidobacterial species were used as an outgroup. Bootstrap percentages above 50 are shown at node points based on 1000 replicates of the phylogenetic tree. The outer circle represents the number of accessory and unique genes as well as the genome size of each bifidobacterial type strain, while the ecological origins of bifidobacteria per each phylogenetic group are reported beside the phylogenetic tree.