bifidum

Bifidobacterium bifidum is a Gram-positive, anaerobic, non-spore-forming bacterium and the type species of the genus Bifidobacterium. It is part of the phylum Actinobacteria and is frequently found in the human gastrointestinal tract, especially in infants, where it contributes to the initial establishment of the gut microbiota. The species is also isolated from dairy products and is used in probiotic products.

Morphology and growth: It is a rod-shaped, non-motile bacterium. It grows best under anaerobic conditions at human body temperature and tolerates mildly acidic environments typical of the gut.

Metabolism: B. bifidum uses the bifid shunt, or fructose-6-phosphate phosphoketolase pathway, to ferment carbohydrates, producing acetate and lactate as the main end products, with occasional formate or ethanol in some strains. It can utilize a variety of carbohydrates, including lactose, galactose, and certain human milk oligosaccharides.

Genomics and ecology: The genome is typically around 2.0–2.5 million base pairs in a single circular chromosome, with strain-to-strain variation and occasional plasmids. It is a common constituent of the early-life gut microbiota and interacts with other microbes through cross-feeding and metabolic byproducts.

Health and applications: B. bifidum strains are used as probiotics in dietary supplements and infant formulas. They are studied for potential benefits in digestive health, immune modulation, and barrier function, but effects are often strain- and context-dependent. Safety is generally good for healthy individuals; rare cases of sepsis have been reported in severely immunocompromised patients.