(191f) Economical Production of Propionic Acid from Renewable Feedstocks by Propionibacteria in a Fibrous-bed Bioreactor

Propionic acid is an important chemical with various industrial applications. Propionibacterium freudenreichii subsp. shermanii, typically used as ripening culture for Swiss-type cheese, has been studied for its ability to produce propionic acid and vitamin B₁₂. A P. shermanii strain with high propionic acid yield was used for propionic acid production by cells immobilized in a fibrous-bed bioreactor (FBB). Batch and fed-batch fermentations with glycerol and glucose as carbon sources were investigated first. The results showed that the strain was able to convert both glucose and glycerol simultaneously to propionic acid at a high rate and with a high propionic acid yield.  Then, the fermentation was studied using cassava bagasse hydrolysate and crude glycerol from biodiesel wastes to demonstrate the feasibility of using low-cost feedstocks to economically produce propionic acid.