Bilophila wadsworthia is a Gram-negative, obligate anaerobic, sulfite-reducing bacterium that has emerged as a key pathobiont linking high-fat diets, taurine metabolism, hydrogen sulfide production, and inflammatory disease. Its unique metabolic niche -- using taurine-conjugated bile acids as an electron acceptor -- positions it at the intersection of dietary fat intake, bile acids, and gut inflammation.
Metabolic Specialization
Taurine to H2S Pathway
- B. wadsworthia metabolizes taurine (from taurine-conjugated bile acids) via taurine dehydrogenase, producing hydrogen sulfide (H2S) as an end product.
- H2S is genotoxic, inhibits butyrate oxidation in colonocytes, and disrupts the mucus barrier.
- Taurine-conjugated bile acids increase with high-saturated-fat diets, providing the metabolic substrate that fuels B. wadsworthia expansion.
Hydrogen Utilization
- Uses H2 as an energy source via hydrogenase enzymes, positioning it within the gut hydrogen economy.
- H2 consumption by B. wadsworthia can shift the thermodynamics of fermentation by other gut bacteria, influencing overall community metabolism.
Iron and Molybdenum Dependencies
- The dissimilatory sulfite reductase (DsrAB) that generates H2S contains iron-sulfur clusters, making B. wadsworthia dependent on iron availability.
- Taurine dehydrogenase requires a molybdenum cofactor, linking its pathogenic metabolism to trace metal availability.
Disease Associations
Colorectal Cancer
- Significantly more abundant in uninvolved colonic mucosa of CRC cases versus controls among African American/Black individuals [mcleod 2023 bridge crc mediterranean diet trial].
- H2S production dampens butyrate metabolism in colonocytes, creating a pro-tumorigenic environment.
- Mediterranean diet intervention aims to reduce B. wadsworthia abundance by shifting bile acid conjugation patterns away from taurine.
Multiple Sclerosis
- Enriched in MS progressors (patients with worsening disability) and significantly stratifies disease progression risk in Kaplan-Meier analysis [montgomery 2024 microbiota signatures ms progression].
- As a sulfate-reducing bacterium producing H2S, it may drive oxidative stress and inflammation in the gut brain axis.
- May thrive in metal-rich environments, connecting MS progression to environmental metal exposure.
Cardiovascular Disease
- Correlated with altered lipid metabolites (traumatic acid) in viral myocarditis models [xue 2024 colonic microflora metabolic viral myocarditis cvb3].
- Hypertension MR studies show decreased Bilophila in hypertensive individuals [li 2023 gut microbiome hypertension bidirectional mr].
IBD
- Enriched in inflammatory bowel disease, where its H2S production exacerbates mucosal inflammation.
- Taurine-rich diets (high in animal protein) promote B. wadsworthia expansion and colitis in susceptible hosts.
Other Conditions
- Arsenic exposure increases Bilophila abundance and perturbs bile acid homeostasis [zhu 2024 toxic essential metals gut microbiota].
- Altered in autism spectrum disorder gut mycobiome-bacteriome interaction studies [strati 2017 altered gut microbiota mycobiota asd].
- Decreased in Huntington's disease [khatoon 2023 gut microbiota neurodegenerative].
Dietary Modulation
The abundance of B. wadsworthia is highly responsive to diet:
- Increased by: high-saturated-fat diets, high-taurine diets (animal protein), Western-style diets.
- Decreased by: Mediterranean diet, plant-based diets, high-fiber diets that shift bile acid profiles toward glycine conjugation.
Connections
- bile acids -- metabolizes taurine-conjugated bile acids to H2S
- iron -- Fe-S cluster dependency in sulfite reductase
- colorectal cancer -- enriched in CRC; H2S impairs colonocyte butyrate oxidation
- multiple sclerosis -- enriched in MS progressors; stratifies disease progression risk
- inflammatory bowel disease -- H2S-mediated mucosal damage exacerbates colitis
- cardiovascular disease -- altered in CVD and hypertension contexts
- oxidative stress -- H2S and sulfide-mediated oxidative damage
- arsenic -- As exposure increases Bilophila abundance
- hydrogenase -- uses H2 as energy source via hydrogenase enzymes