A Gram-positive, obligate anaerobic genus within the lachnospiraceae family (Firmicutes phylum). Coprococcus is one of the most important butyrate-producing commensals in the human gut and has gained particular attention as the "happiness bug" — one of very few taxa directly linked to mental health outcomes through population-level studies. Key species include C. eutactus and C. catus, both prolific short chain fatty acids producers.
Role in Gut Ecosystem
- Primary butyrate producer via the butyryl-CoA:acetate CoA-transferase pathway, generating the most potent anti-inflammatory SCFA in the colon.
- C. catus also produces significant propionate via the acrylate pathway, making it one of few organisms that produces both butyrate and propionate.
- Contributes to colonization resistance and gut barrier maintenance through butyrate-mediated upregulation of tight junction proteins and mucin production.
- Cross-feeds with acetate producers and mucin-degrading bacteria like akkermansia muciniphila in the healthy gut fermentation network.
The "Happiness Bug" -- Mental Health Link
- The landmark Valles-Colomer 2019 study identified Coprococcus (alongside faecalibacterium prausnitzii) as consistently depleted in individuals with depression, even after controlling for antidepressant use — one of the first population-scale microbiome-mental health associations.
- Coprococcus produces DOPAC (3,4-dihydroxyphenylacetic acid), a dopamine metabolite, providing a plausible mechanism for its mental health associations via the gut brain axis.
- Consistently decreased in autism spectrum disorder youth across multiple observational reviews [1].
- Depleted in schizophrenia patients alongside other SCFA producers, consistent with the dysbiosis-inflammation-neurotransmitter axis in psychotic disorders [2] [3].
Sensitivity to Heavy Metals
- Coprococcus is among the SCFA-producing taxa most sensitive to heavy metals toxicity, particularly cadmium and lead [4].
- Lead exposure depletes Coprococcus, contributing to the ASD-metal-microbiome triad where Pb-induced loss of butyrate producers may exacerbate neurodevelopmental symptoms [5].
- Its cobalt/B12-dependent metabolic pathways make it vulnerable to metal competition and displacement by heavy metals at enzyme active sites.
Disease Associations
Depression and Mental Health
- Depleted in major depressive disorder; DOPAC production links it mechanistically to dopaminergic signaling.
Multiple Sclerosis
- Reduced 3.4-fold in MS patients compared to healthy controls in the Saresella 2020 study, part of the dramatic Lachnospiraceae depletion that characterizes MS dysbiosis [6].
- Loss correlates with reduced serum butyric acid and increased gut barrier permeability (elevated LPS and I-FABP).
Inflammatory Bowel Disease
- Depleted in both Crohn's disease and ulcerative colitis, consistent with the general loss of butyrate producers in IBD.
Cardiovascular Disease
- Coprococcus (Coprococcus1) is causally protective against coronary artery disease (OR=0.867) in MR analysis [7].
Colorectal Cancer
- Depleted in CRC; part of the butyrate-producing consortium lost during tumorigenesis [8].
Ovarian Cancer
- Altered Coprococcus abundance contributes to the diagnostic gut microbiome signature distinguishing ovarian tumor patients from healthy controls, consistent with the broad depletion of butyrate producers across gynecological cancers [9].
Chronic Kidney Disease
- Depleted as part of the broader loss of butyrate-producing consortia in CKD; reduced SCFA availability contributes to uremic toxin accumulation and gut-kidney axis dysfunction [10] [11].
Key Metabolites
- Butyrate — primary product; HDAC inhibitor, anti-inflammatory, gut barrier protectant
- Propionate — produced by C. catus via acrylate pathway; metabolic regulator
- DOPAC — dopamine metabolite; potential mediator of gut-brain mental health effects
Connections
- faecalibacterium prausnitzii — fellow butyrate producer; co-depleted in depression, IBD, and MS
- short chain fatty acids — one of the most important butyrate producers in the human gut
- gut brain axis — DOPAC production links gut fermentation to dopaminergic neurotransmission
- multiple sclerosis — dramatically depleted; loss contributes to barrier dysfunction
- autism spectrum disorder — depleted in ASD; lead exposure may drive this depletion
- lead — particularly sensitive to Pb; metal-induced loss may mediate neurobehavioral effects
- cardiovascular disease — causally protective against CAD per MR evidence
- colorectal cancer — depleted; loss removes tumor-suppressive butyrate HDAC inhibition
- dorea — Lachnospiraceae relative with opposite disease pattern (enriched in disease)