Bifidobacterium
（重定向自Bifidus）
Bifidobacterium is a genus of gram-positive, nonmotile, often branched anaerobic bacteria. They are ubiquitous inhabitants of the gastrointestinal tract, vagina and mouth (B. dentium) of mammals, including humans. Bifidobacteria are one of the major genera of bacteria that make up the colon flora in mammals. Some bifidobacteria are used as probiotics.