General Information: Common oral and gut bacterium. Representatives of this genus naturally colonize the human gastrointestinal tract (GIT) and are important for establishing and maintaining homeostasis of the intestinal ecosystem to allow for normal digestion. Their presence has been associated with beneficial health effects, such as prevention of diarrhea, amelioration of lactose intolerance, or immunomodulation. The stabilizing effect on GIT microflora is attributed to the capacity of bifidobacteria to produce bacteriocins, which are bacteriostatic agents with a broad spectrum of action, and to their pH-reducing activity. Most of the ~30 known species of bifidobacteria have been isolated from the mammalian GIT, and some from the vaginal and oral cavity. All are obligate anaerobes belonging to the Actinomycetales, branch of Gram-positive bacteria with high GC content that also includes Corynebacteria, Mycobacteria, and Streptomycetes. Bifidobacterium dentium species represents over forty strains which were isolated from human dental caries and human feces.