Bifidobacterium longum

Bifidobacterium longum Reuter 1963 is the bifidobacterial species most often specified in adult supplement formulations, and the one where getting the paperwork right matters most. The species carries several validly published subspecies — subsp. longum, subsp. infantis, subsp. suis, subsp. suillum and subsp. iuvenis — and they are not interchangeable commercially. Subsp. infantis is the human-milk-oligosaccharide specialist and is documented, regulated and priced quite separately from subsp. longum. A purchase order that says only "Bifidobacterium longum" is under-specified, so we require the subspecies on the specification and confirm it on the certificate of analysis. The species reference strain is ATCC 15707 = DSM 20219 = JCM 1217 = CIP 64.62 = LMG 10497. The organism is a Gram-positive, non-motile, frequently club- or Y-shaped rod of the family Bifidobacteriaceae, phylum Actinomycetota, and a strict anaerobe. Sequenced isolates run to roughly 2.26 Mb at 59.9 to 60 mol% G+C, with about 1,730 coding sequences in the infant-derived genome first published in 2002 — a compact chromosome whose gene complement reflects adaptation to the human gastrointestinal tract. Like all bifidobacteria it ferments hexoses through the fructose-6-phosphate (bifid) shunt, giving acetate and lactate; fructose-6-phosphate phosphoketolase activity remains the classical confirmatory assay for the genus. Among the named commercial entities, B. longum subsp. longum BB536 is deposited as ATCC BAA-999 and was isolated in June 1969 from the faeces of a healthy infant. Material is supplied as a lyophilised live culture concentrate standardised on colony-forming units, either as bulk powder for your own blending or filled into HPMC or gelatin capsules at your dose, with overage set to hold label claim to the end of the stated shelf life. Being a strict anaerobe it is oxygen-, moisture- and heat-sensitive, and downstream blending, encapsulation and blistering conditions govern retained potency as much as the release count does. Every lot ships with a certificate of analysis carrying strain and subspecies identity, viable count, moisture, water activity and microbiological purity, plus antimicrobial-resistance screening — the generic qualification EFSA applies to all QPS-listed bacterial taxonomic units is that strains carry no acquired resistance to therapeutic antimicrobials. Bifidobacterial media commonly contain milk-derived peptones or whey, so allergen status is declared lot by lot and dairy-free grades are available. FSSAI requires a probiotic product to draw its organism from Schedule VII and to deliver at least 10⁸ CFU in the recommended daily serving unless a lower count is approved on evidence. We describe composition and viable count only, and make no therapeutic or disease claims.