(200e) Enhanced Propionic Acid Production by Engineered Propionibacteria Overexpressing CoA Transferase in Extractive Fermentation

Propionic acid is an important chemical that is almost exclusively produced by the petrochemical industry. Propionic acid fermentation by Propionibacterium acidipropionici provides an alternative and green route for propionic acid production, but is limited by its low productivity. The last and key step of propionic acid biosynthesis is catalyzed by propionyl-CoA: succinate CoA transferase (CoA T). To increase propionic acid production, CoA transferase was overexpressed in propionibacteria. Compared to the wild type, the mutant showed faster growth and higher tolerance to propionic acid and acidic pH. The effects of overexpressing CoA transferase on propionic acid production were studied in batch fermentation, and the results showed propionic acid production increased ~20% as compared to the wild type. Adaptation of the mutant in a fibrous bed bioreactor (FBB) was then used to further increase its propionic acid tolerance and production. Finally, extractive fermentation with the FBB and simultaneous propionic acid recovery through a hollow-fiber membrane extractor was developed for the production of propionic acid from sugars and other renewable resources. The integrated fermentation-separation process provides an economical method to produce biobased propionic acid for industrial use.