Bacteroides Uniformis

A Gram-negative, obligate anaerobic bacterium within the phylum Bacteroidetes and a common member of the healthy human gut microbiota. B. uniformis is a versatile polysaccharide degrader with emerging significance as an anti-inflammatory commensal whose depletion appears across multiple disease states linked to metal dyshomeostasis.

Metabolic Functions

  • Possesses an extensive repertoire of polysaccharide utilization loci (PULs) enabling degradation of complex dietary fibers, resistant starches, and host-derived glycans.
  • Produces short chain fatty acids — primarily acetate and propionate — from fiber fermentation, contributing to colonocyte energy supply and immune regulation.
  • Dietary fiber intake directly increases B. uniformis abundance. In a cohort of healthy men, higher fiber consumption correlated with enrichment of B. uniformis alongside reduced systemic inflammation markers ma 2021 dietary fiber gut microbiome inflammation men.
  • Participates in bile acid metabolism through bile salt hydrolase activity, influencing the enterohepatic circulation of bile acids.

Immune Modulation

  • B. uniformis has demonstrated anti-inflammatory properties in preclinical models, reducing pro-inflammatory cytokine production (TNF-alpha, IL-6) while promoting regulatory T cell differentiation.
  • Its polysaccharide capsule components interact with the host immune system via TLR2 and Dectin-1 pathways.
  • Unlike some Bacteroides species (e.g., bacteroides fragilis with its BFT toxin), B. uniformis lacks known virulence factors and is considered a beneficial commensal.

Depletion in Disease States

B. uniformis depletion is a recurring finding across conditions with distinct metal and inflammatory profiles:

  • Chronic kidney disease (CKD): Depleted in CKD rat models, where uremic toxin accumulation and metal dyshomeostasis reshape the gut microbiome. Fecal microbiota transplantation from healthy donors restores B. uniformis abundance alongside improvements in renal function markers liu 2022 fmt restores ckd rats.
  • Autism spectrum disorder (ASD): Reduced in young ASD children compared to neurotypical controls. The depletion correlates with altered short chain fatty acids profiles and may contribute to the GI symptoms common in ASD coretti 2018 gut microbiota young asd children.
  • Gastroesophageal reflux disease (GERD): Identified as a depleted taxon in GERD patients in systematic review findings, suggesting a role in upper GI homeostasis alageel 2025 microbiome composition gerd systematic review.

Metal Dependencies and Sensitivity

  • Like other Bacteroides, B. uniformis requires iron for respiratory chain enzymes and zinc for metalloprotease activity.
  • Its sensitivity to metal perturbation is not yet characterized at the species level, but the genus Bacteroides is known to shift in composition under heavy metal exposure, with some species expanding (e.g., B. fragilis) while commensals like B. uniformis may be outcompeted.

Ecological Role

  • Functions as a primary degrader in the gut, breaking down complex polysaccharides into simpler substrates that feed secondary fermenters including butyrate producers like faecalibacterium prausnitzii and eubacterium rectale.
  • Its loss disrupts the fiber fermentation cascade, reducing SCFA availability and potentially contributing to the pro-inflammatory environment seen in dysbiotic states.

Cross-References

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