Blautia

SCFA Production and Bile Acid Metabolism#

Produces acetate as its primary fermentation end-product, with some species also generating Butyrate and propionate.

B. hydrogenotrophica is a unique acetogen that converts H2 and CO2 into acetate via the Wood-Ljungdahl pathway, providing a critical hydrogen sink in the gut ecosystem.

Active in bile acid transformation: deconjugation via bile salt hydrolase (BSH) activity and downstream secondary bile acid modifications. This places Blautia at the intersection of lipid metabolism and gut-liver axis signaling.

Bile acid metabolism by Blautia affects FXR and TGR5 receptor signaling, influencing cholesterol homeostasis, glucose metabolism, and Metal-Driven Inflammation.

Depleted in Disease#

IBD: B. obeum depleted in Crohn's disease and ulcerative colitis; its loss reduces SCFA-mediated mucosal protection. Colorectal cancer: reduced in CRC patients alongside other Lachnospiraceae members. Carotid atherosclerosis: part of the depleted SCFA-producing network in subclinical CVD.^{[1]Network of Interactions Between Gut Microbiome, Host Biomarkers, and Urine Metabolome in Carotid AtherosclerosisRui-Jun Li, Zhu-Ye Jie, Qiang Feng et al. · 2021Open reference 1 ↓}

Enriched in Disease (Context-Dependent)#

Multiple sclerosis: some Blautia species are paradoxically increased in MS patients, potentially reflecting a compensatory shift or pro-inflammatory capacity in the neuroinflammatory context.^{[2]Feeding the gut microbiome: impact on multiple sclerosisMatteo Bronzini, Alessandro Maglione, Rachele Rosso et al. · 2023Open reference 2 ↓}

Endometriosis: Blautia abundance altered by hormonal treatment in endometriosis patients, suggesting sensitivity to estrogen-modulating therapies.^{[3]Associations Between Endometriosis and Gut MicrobiotaSvensson A, Brunkwall L, Roth B et al. · 2021Open reference 3 ↓}

Role in Gut Ecosystem#

Functions as a metabolic hub connecting fiber fermentation, bile acid cycling, and gas metabolism. Hydrogen consumption by B. hydrogenotrophica prevents H2 accumulation that would thermodynamically inhibit fiber fermentation by other bacteria.

Cross-feeds with butyrate producers: acetate from Blautia serves as a substrate for butyryl-CoA:acetate CoA-transferase in Roseburia and Faecalibacterium prausnitzii, enabling butyrate production. The genus occupies a middle trophic level in the colonic food web, connecting primary fiber degraders (Ruminococcus R. bromii) to terminal butyrate producers.

Metal Sensitivity#

As a Lachnospiraceae member, Blautia shares the family-wide sensitivity to heavy metal stress. Iron-sulfur cluster enzymes in the Wood-Ljungdahl pathway of acetogenic species are particularly vulnerable to metal disruption. Cadmium and Lead exposure depletes Blautia alongside other SCFA producers in the Gut-Metal-Microbiome Interactions framework.

Key Metabolites#

Acetate—primary fermentation product; substrate for butyrate producers. Bile acid derivatives—BSH-mediated deconjugation and secondary bile acid production. Hydrogen consumption—acetogenic species convert H2/CO2 to acetate, regulating gut gas homeostasis.