Figure 2.

SCFA biosynthesis pathways from the dietary carbohydrate fermentation and the major SCFA-producing bacteria for each pathway

Acetate can be formed by the Wood-Ljungdahl pathway and from pyruvate via acetyl-CoA. Acetyl-CoA can be also produced from lactate by lactate-utilizing bacteria. Three pathways exist for the propionate formation, namely acrylate, succinate, and propanediol pathways. The two first use PEP and the latter utilizes deoxy sugars such as rhamnose and fucose. Butyrate can be formed through the classical pathway from the condensation of two acetyl-CoA molecules or by the butyryl-CoA: acetate CoA-transferase route, in which butyryl-CoA is converted into butyrate and acetyl-CoA using exogenously derived acetate. DHAP, dihydroxyacetone phosphate; PEP, phosphoenolpyruvate. Created with BioRender.com