Bifidobacterium

Abstract

The genus Bifidobacterium includes high G + C gram-positive nonspore-forming, nonmotile, and nonfilamentous polymorphic rod-shaped bacteria that can display slight bends or a large variety of branchings, the slightly bifurcated club-shaped or spatulated extremities being the most commonly found. They can be organized singly or in chains, in star-like aggregates, in "V," or in palisade arrangements when grown in vitro. They are strictly anaerobic, although some species, such as Bifidobacterium animalis and Bifidobacterium psychraerophilum, can tolerate moderately high oxygen concentrations, and they have a fermentative metabolism.1,2 Bifidobacteria were first described at the beginning of the twentieth century and were included among the family Lactobacillaceae.3 In 1924, Lactobacillus bifidum was reclassified as the new genus Bifidobacterium by Orla-Jensen.1