A genus of Gram-positive, obligate anaerobic bacteria within the Firmicutes phylum that includes several of the most important butyrate producers in the human colon. Key species are E. rectale, E. hallii (now reclassified as Anaerobutyricum hallii), and E. limosum. Consistently depleted in inflammatory and cardiometabolic diseases, Eubacterium species are part of the core SCFA-producing guild alongside faecalibacterium prausnitzii and roseburia.
Butyrate Production
E. rectale
- One of the most abundant butyrate producers in the healthy human colon, often ranking alongside F. prausnitzii in absolute abundance.
- Ferments dietary fiber (resistant starch, xylan) via the butyryl-CoA:acetate CoA-transferase pathway.
- Butyrate output supports colonocyte energy metabolism, tight junction integrity, and anti-inflammatory HDAC inhibition.
- Depleted in cardiovascular disease: part of the butyrate-producing guild lost in CVD patients [almeida 2023 gut microbiota cardiovascular axis].
E. hallii (Anaerobutyricum hallii)
- Reclassified but still widely referenced by its original name.
- Unique metabolic versatility: converts lactate, acetate, and 1,2-propanediol to butyrate and propionate, acting as a metabolic cross-feeder that recycles fermentation intermediates.
- This lactate-to-butyrate conversion is critical during rapid fermentation when lactate accumulates and could otherwise acidify the colonic environment to harmful levels.
- Produces vitamin B12 (cobalamin), linking its metabolism to cobalt availability.
E. limosum
- Converts dietary fiber to butyrate; also metabolizes methanol and betaine.
- Possesses demethylating activity that may affect epigenetic regulation in the colonic epithelium.
Disease Associations
- Cardiovascular disease: E. rectale depleted in CVD patients; its loss reduces butyrate-mediated cardioprotective effects [almeida 2023 gut microbiota cardiovascular axis, liu 2019 gut microbiome metabolism cad severity].
- IBD: consistently reduced in both Crohn's disease and ulcerative colitis; inversely correlated with inflammatory markers. Polyphenol interventions can partially restore Eubacterium abundance [li 2020 polyphenols gut microbiota ibd synergy].
- Colorectal cancer: depleted in CRC; butyrate loss diminishes HDAC-mediated tumor suppression [zou 2024 multi omic microbiome genome transcriptome crc].
- Type 2 diabetes: reduced; metformin treatment partially restores abundance.
Metal Dependencies
- Iron-sulfur clusters in ferredoxins and butyrate synthesis enzymes are essential for anaerobic metabolism.
- Butyrate production pathway depends on intact Fe-S cluster function, making Eubacterium vulnerable to iron perturbation and heavy metal displacement.
- Cobalt is required for B12 synthesis in E. hallii, linking its metabolic capacity to trace metal availability in the gut metal microbiome.
- Heavy metal exposure (cadmium, lead) depletes Eubacterium alongside other SCFA producers, reducing the colonic butyrate pool.
Key Metabolites
- Butyrate -- primary output from E. rectale and E. hallii; HDAC inhibitor, anti-inflammatory, colonocyte fuel.
- Propionate -- produced by E. hallii from 1,2-propanediol; improves insulin sensitivity and reduces hepatic lipogenesis.
- Vitamin B12 -- synthesized by E. hallii; essential coenzyme for methylation reactions.
- Lactate recycling -- E. hallii prevents harmful lactate accumulation by converting it to butyrate.
Connections
- faecalibacterium prausnitzii -- co-dominant butyrate producer; co-depleted across disease states
- roseburia -- complementary SCFA producer within the butyrate-producing guild
- lachnospiraceae -- taxonomic relationship; shares depletion pattern
- cardiovascular disease -- E. rectale depletion reduces cardioprotective butyrate
- colorectal cancer -- butyrate loss diminishes anti-tumorigenic HDAC inhibition
- crohns disease -- depleted; polyphenol interventions may partially restore
- iron -- Fe-S clusters essential for butyrate synthesis enzymes
- cobalt -- B12 synthesis in E. hallii depends on cobalt availability
- dysbiosis -- depletion is a consistent feature of disease-associated dysbiosis
- inflammation -- butyrate/HDAC/GPR109A anti-inflammatory axis
- gut metal microbiome -- metal sensitivity links environmental exposure to SCFA production loss