Short-Chain Fatty Acids (SCFAs)-Producing Bacteria

Fermentation and SCFA Production

Bacteria ferment Microbiota-accessible carbohydrates (MACs) to produce Short-Chain Fatty Acids (SCFAs), which have significant effects on host health, signal transduction pathways, and immunity (Hryckowian et al. 2018). This fermentation process also reduces luminal pH (Overby & Ferguson 2021 Current Hypertension Reports 23: 8).

Short-chain fatty acids (SCFAs) are produced by anaerobic gut bacteria through saccharolytic fermentation of complex resistant carbohydrates (e.g., fructooligosaccharides , sugar alcohols , starch , inulin , and polysaccharides from plant cell walls), which escape digestion and absorption in the small intestine (Richards et al. 2016 PharmaNutrition 4:68-111).

The enzymatic processes necessary for the fermentation of fiber to SCFAs are largely dependent upon bacteria within the Clostridia class (Pryde et al. 2002 FEMS Microbiology Letters. 217: 133–139) and others.

In the caecum and right colon, fermentation is very intense, leading to high production of SCFAs, an acidic pH (5–6), and rapid bacterial growth (Cummings et al. 1987 Gut 28: 1221-1227; Macfarlane et al. 1992).

Specific Carbohydrates

Starch and non-starch polysaccharides that human enzymes cannot degrade are broken down to SCFAs by various bacterial species such as Roseburia and Faecalibacterium prausnitzii through primary bacterial butyrate synthesis pathways, including Butyryl-CoA: acetate CoA-transferase (but) and Butyrate kinase (buk)
Vital et al. 2013 Microbiome. 1(1): 8

Key Bacterial Species

Odoribacter splachnicus

Odoribacter splachnicus is involved in SCFA production. The loss of Odoribacter splachnicus results in reduced SCFA availability, leading to host inflammation (King et al. 2019).

Bifidobacterium pseudocatenulatum

Bifidobacterium pseudocatenulatum is one of the most significantly promoted SCFA producers (Zhao et al. 2018c).

Other Important Bacteria

The increase in the Bacteroidetes to Firmicutes ratio, as well as the abundance of Ruminococcaceae, Bifidobacterium / Bifidobacter, and Lactobacillus, is associated with SCFA production (Bindels et al. 2015 Nat. Rev. Gastroenterol. Hepatol. 12: 303-310; Zhang et al. 2015c Int. J. Mol. Sci.16: 7493-7519; Ohira et al. 2017 J. Atheroscler. Thromb. 24: 660-672).

see also:
Acetate & Clostridia
Bifidobacterium pseudocatenulatum & Short-Chain Fatty Acids (SCFAs)
Clostridia & Propanoate Metabolism / Propionate / Propionic acid
Short-Chain Fatty Acids (SCFAs)
SCFAs-Producing Bacteria & Examples