TAXONOMY: Bacteria -> Terrabacteria group -> Actinobacteria -> Actinobacteria -> Bifidobacteriales -> Bifidobacteriaceae -> Bifidobacterium
'Bifidobacterium' is a genus of Gram-positive, nonmotile, often branched anaerobic bacteria. They are ubiquitous inhabitants of the gastrointestinal tract, vagina and mouth (Bifidobacterium dentium 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. Before the 1960s, Bifidobacterium species were collectively referred to as 'Lactobacillus bifidus'. Soybean oligosaccharides increase the bifidobacateria population 2 to 10-fold in human subjects.More recently, members of the Bifidobacterium genus were shown to enhance the immune response to tumours in a manner that increased the efficacy of anti-programmed death ligand 1 (α-PDL1), an antibody that blocks immune inhibitory pathways.[PMID: 24264989] Lactobacillus and Bifidobacterium synthesize gamma-aminobutyric acid (GABA) from monosodium glutamate. [PMID: 26598580] An infusion of dandelion root (Taraxacum officinale) stimulated the growth of 14 strains of bifidobacteria in vitro. [PMID 15567259]
Rods of various shapes: short, regular, thin cells with pointed ends, coccoidal regular cells, or long cells with slight bends or protuberances or with a large variety of branching; pointed, with slightly bifurcated club-shaped or spatulated extremities; may occur singly or in chains of many elements; may occur in star-like aggregates or in “V” or “palisade” arrangements. Colonies are smooth, convex with entire edges, cream to white, glistening, and of soft consistency. Gram-stain-positive, non-acid-fast, nonsporeforming, and nonmotile. Cells often stain irregularly with methylene blue. Anaerobic; some species can tolerate O2, but only in the presence of CO2 and the more recently described species, such as Bifidobacterium psychraerophilum, Bifidobacterium scardovii, and Bifidobacterium tsurumiense, can grow under aerobic conditions (Okamoto et al., 2008). Optimum growth temperature is 37–41°C, except for Bifidobacterium mongoliense, which exhibits an optimal growth temperature of 30°C; minimum growth temperature is 25–28°C, with the exception of Bifidobacterium mongoliense and Bifidobacterium psychraerophilum, which can grow at 15°C and 8°C, respectively; maximum growth temperature is 43–45°C, with the exception of Bifidobacterium thermacidophilum, which exhibits a maximal growth temperature of 49.5°C. Growth at 45°C seems to discriminate between animal and human strains, since most of the animal but not the human strains are able to grow at this temperature (Gavini et al., 1991). Optimum pH for initial growth is 6.5–7.0; does not grow at pH 4.5–5.0 (except for Bifidobacterium thermacidophilum, which can grow at pH 4.5) or pH 8.0–8.5. DNA G+C content (mol%): 47–67 (Bd or Tm). Type species: Bifidobacterium bifidum
This genus contains microbial species that can reside in the human gastrointestinal tract. [PMC 4262072]
Blood group H-degrading activity; sialidase; β-galactosidase (B. bifidum) Blood group H-degrading activity; sialidase; β-galactosidase (B. longum subsp. infantis) [PMC 4365749] Decreased in metabolic disorders.
A significant association was observed between commensal microbial composition and clinical response to anti-PD-1-based immunotherapy. Bacterial species more abundant in responders included Bifidobacterium longum, Collinsella aerofaciens, and Enterococcus faecium. PMID: 29302014