Bacteroidales is an order of obligate anaerobic, Gram-negative bacteria within the phylum Bacteroidetes. It includes the families Bacteroidaceae (bacteroides), Prevotellaceae (prevotella), Rikenellaceae, and Porphyromonadaceae (porphyromonas). Bacteroidales are among the most abundant gut commensals, specializing in complex polysaccharide degradation via their signature polysaccharide utilization loci (PULs).
Ecological Role
- Fiber fermentation: Bacteroidales encode extensive PUL systems for degrading dietary fiber, resistant starch, and host-derived glycans (mucin) — making them the primary fiber-fermenting order in the gut.
- SCFA production: Major producers of propionate and acetate (less butyrate than Firmicutes).
- Bile acid metabolism: Bacteroidales possess bile salt hydrolases that deconjugate primary bile acids.
- Diet-responsive: Mediterranean and fiber-rich diets increase Bacteroidales abundance latorre perez 2021 spanish gut microbiome mediterranean diet ross 2024 diet gut microbiome interplay health disease.
Disease Associations
- T1D: Altered Bacteroidales in autoimmune beta-cell destruction honkanen 2020 fungal dysbiosis intestinal inflammation beta cell autoimmunity.
- CRC: Immunotherapy response (PD-1 blockade) associated with Bacteroidales abundance xu 2020 gut microbiome pd1 mss crc metabolic pathway.
- CKD: Dietary fiber modulates Bacteroidales and downstream metabolome hall 2020 ckd cats dietary fiber metabolome microbiome.
Cross-References
- bacteroides — dominant genus
- prevotella — fiber-associated genus
- bacteroidetes — phylum context
- dietary fiber — substrate for Bacteroidales PUL systems
- short chain fatty acids — metabolic output