Bifidobacteria: General overview on ecology, taxonomy, and genomics

Bifidobacteria were originally identified from stool samples of breast-fed infants in 1899 by Tissier, and termed Bacillus bifidus (Tissier 1900). Thereafter different designations have been employed such as Bacteroides bifidus and Lactobacillus bifidus. From 1973 bifidobacteria have been classified as a distinct genus (i.e., Bifidobacterium), originally including 11 species (Poupard et al. 1973). Later, Scardovi updated the number of bifidobacterial species to 24, which reached the latest number of 33 taxa (Ventura et al. 2007b), with the recent description of the new species Bifidobacterium bombi (Killer et al. 2009) and Bifidobacterium crudilactis (Delcenserie et al. 2007).