Bifidobacterium spp.: the pathway in the body

Bifidobacterium spp. is part of the pathway “Gut bacteria”. This page shows the whole pathway; the station of Bifidobacterium spp. is highlighted.

Where this laboratory value sits: Bifidobacterium — Bifidobacteria. Bifidobacteria break down dietary fibre with their own enzymes and ferment the building blocks via a special route, the bifid shunt. Source 2

In brief

Gut bacteria such as bifidobacteria, lactobacilli, Faecalibacterium and Akkermansia live mainly in the large intestine. They ferment dietary fibre and mucus sugars into short-chain fatty acids such as acetate, propionate and butyrate, which gut cells use as fuel and signal.

The pathway step by step

1. Dietary fibre → Lactate and acetate Glycosidases Bacterial glycosidases split the long chains into sugar units; fermentation yields lactic acid, acetate and gases. Source 1, 2
2. Lactate and acetate → Butyrate Butyryl-CoA transf. Butyrate producers use acetate and lactate from their neighbours; this handing-on is called cross-feeding. The enzyme butyryl-CoA:acetate CoA-transferase carries out the final step. Source 1, 5
3. Butyrate → Gut wall cells β-oxidation · MCT transporter The cells of the colonic lining absorb butyrate and burn it in their mitochondria. It covers a large part of their energy needs. Source 3, 1
4. Mucus (mucin) → Acetate and propionate Mucin glycosidases Breaking down the mucin sugar chains produces acetate and propionate. Other species nearby make further use of these substances. Source 4, 1
5. Acetate and propionate → FFAR2 and FFAR3 Acetate and propionate bind to the receptors FFAR2 and FFAR3 on gut, fat and immune cells. Through them they act as signalling molecules, not just as fuel. Source 3

Cofactors in this pathway

• Thiamine (vitamin B1) — As thiamine diphosphate, cofactor of phosphoketolase in the bifid shunt of bifidobacteria Source 6
• Riboflavin (vitamin B2) — As FAD, part of the enzyme pair butyryl-CoA dehydrogenase and EtfAB in butyrate formation Source 7
• Niacin (NAD⁺) — NADH supplies the electrons for the reduction steps in butyrate formation Source 5, 7
• Iron — Iron-sulphur centres in ferredoxin, which accepts electrons during butyrate formation Source 7
• Pantothenic acid (coenzyme A) — Building block of coenzyme A, which butyryl-CoA:acetate CoA-transferase acts on Source 1, 5
• Vitamin B12 (cobamides) — Pseudo-B12 formed by Eubacterium hallii allows Akkermansia to form propionate Source 8

Sources

1. Louis P, Flint HJ. Formation of propionate and butyrate by the human colonic microbiota. Environ Microbiol 2017 · PubMed 27928878
2. Rivière A, Selak M, Lantin D et al. Bifidobacteria and Butyrate-Producing Colon Bacteria: Importance and Strategies for Their Stimulation in the Human Gut. Front Microbiol 2016 · PubMed 27446020
3. Koh A, De Vadder F, Kovatcheva-Datchary P, Bäckhed F. From Dietary Fiber to Host Physiology: Short-Chain Fatty Acids as Key Bacterial Metabolites. Cell 2016 · PubMed 27259147
4. Ioannou A, Berkhout MD, Scott WT et al. Akkermansia muciniphila: biology, microbial ecology, host interactions and therapeutic potential. Nat Rev Microbiol 2025 · PubMed 39406893
5. Louis P, Flint HJ. Diversity, metabolism and microbial ecology of butyrate-producing bacteria from the human large intestine. FEMS Microbiol Lett 2009 · PubMed 19222573
6. Suzuki R, Katayama T, Kim BJ et al. Crystal structures of phosphoketolase: thiamine diphosphate-dependent dehydration mechanism. J Biol Chem 2010 · PubMed 20739284
7. Buckel W, Thauer RK. Flavin-Based Electron Bifurcation, A New Mechanism of Biological Energy Coupling. Chem Rev 2018 · PubMed 29561602
8. Belzer C, Chia LW, Aalvink S et al. Microbial Metabolic Networks at the Mucus Layer Lead to Diet-Independent Butyrate and Vitamin B12 Production by Intestinal Symbionts. mBio 2017 · PubMed 28928206
9. Zmora N, Zilberman-Schapira G, Suez J et al. Personalized Gut Mucosal Colonization Resistance to Empiric Probiotics Is Associated with Unique Host and Microbiome Features. Cell 2018 · PubMed 30193112
10. Hill C, Guarner F, Reid G et al. Expert consensus document. The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic. Nat Rev Gastroenterol Hepatol 2014 · PubMed 24912386

Whole pathway: Gut bacteria

Related pathways

• Gut microbiome — dietary fibre

As of 2026-09-16. Draft written by Claude to schema v2; sources checked in PubMed; expert review pending
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