Bifidobacterium is a genus of Gram-positive, non-motile, often branched anaerobicbacteria. Bifidobacteria are one of the major genera of bacteria that make up the gut flora, the bacteria that reside in the colon. Bifidobacteria aid in digestion, are associated with a lower incidence of allergies (Björkstén et al., 2001) and also prevent some forms of tumor growth (Guarner and Malagelada, 2003). Some bifidobacteria are being used as probiotics.
Before the 1960s, Bifidobacterium species were collectively referred to as "Lactobacillus bifidus".
Guarner F and Malagelada JR. 2003. Gut flora in health and disease.The Lancet, Volume 361, Issue 9356, 8 February 2003, Pages 512-519. Abstract available.It helps your stomach absorb food.