Fig 4.

Synthesis pathways for propionic acid from glycerol, glucose, and lactate in Propionibacterium. The biosynthetic pathway from glycerol to propionic acid proceeds from glycerol to dihydroxyacetone (DHA) to dihydroxyacetone phosphate (DHAP) to phosphoenolpyruvate to pyruvate and oxaloacetate and from oxaloacetate to malate, fumarate, succinate, succinyl coenzyme A (CoA), methylmalonyl CoA, propionyl CoA, and propionate (see arrows). Acetate is the main byproduct in propionic acid production. Gray color indicates the biosynthetic pathway from glycerol to propionic acid.