Bacteroides

The genus Bacteroides includes gram-negative bacteria (rods) and belongs to the core OTUs (>47% of healthy humans) in the healthy human gut. The bacteria are primarily saccharolytic bacteria that metabolize sugar, starch, cellulose and produce the SCFAs acetate, propionate, and succinate.
Macfarlane et al. 1995 In Gastrointestinal and Oesophageal Pathology, 2nd ed., pp. 249-274 [R Whitehead, editor]. Edinburgh: Churchill Livingstone

Bacteroides sp. are prominent members of the human gut microbiota and have a notable genomic plasticity and adaptive capacity
Tawk et al. 2023 Cell Host & Microbe 31(5): 811-826

Bacteroides species play a dual role in the gut microbiota, acting as both commensals and potential pathogens. Under normal conditions, these bacteria promote homeostasis by reinforcing anaerobiosis (maintaining the gut's low-oxygen (anaerobic) environment) and fermenting fibers into short-chain fatty acids (SCFAs), such as propionate. This process not only fuels host oxygen consumption but also provides colonization resistance against pathogens like Salmonella enterica enterica serovar Typhimurium. SCFAs lower the luminal pH and disrupt the intracellular pH homeostasis of pathogens, thereby slowing their growth and metabolism.
Fansler et al. 2026 Trends Microbiol 34(3): 318-329

Human gut microbiome members, notably Bacteroides, contain numerous Polysaccharide utilization loci (PULs) that enable glycan utilization and shape ecological dynamics.
Feng et al. 2022 Cell Host & Microbe 30: 200-215

Differential fitness effects of butyrate within the Bacteroides are mediated by species-level variation in Acyl-CoA thioesterases activity and nucleotide polymorphisms regulating an Coenzyme A transferases (EC 2.8.3). Using in vivo multi-omic profiles, we demonstrate Bacteroides fitness in the human gut is associated together, but not independently, with Acyl-CoA transferase expression and butyrate.
Park et al. 2022 Cell 185: 513-529

Bacteroides strongly correlates with the beta-glucuronidase level.
Elmassry et al. 2021

Bacteroides spp. have the most antibiotic resistance mechanisms, and the highest resistance rates of all obligate anaerobic pathogens
Kim et al. 2017 Immunol Rev. 279(1): 90-105

Mainly Bacteroides eat a lot of protein and animal fats, which are typical of the western diet.
Arumugam et al. 2011 Nature 473(7346): 174-180

Bacteroides have the potential for either harmful pathogenic effects or for health-promoting functions.
Salminen et al. 1998

Bacteroides species account for approximately 20% of the normal flora of the human colon
Moore & Holdeman 1974 Appl. Microbiol. 27: 961-979
Holdeman et al. 1976 Appl. Environ. Microbiol. 31: 359-375

These species are saccharolytic and are known to ferment a variety of simple sugars
Holdeman & Moore (ed.) 1975 3rd ed. Virginia Polytechnic Institute and State University, Blacksburg, Va.

see also:
Acetate-producing bacteria
Bacteroides thetaiotaomicron
Composition & Gut microbiota
Enterotoxigenic Bacteroides fragilis (ETBF)