Global production of propionic acid is increasing year by year through petroleum routes and the market is demanding for biologically and sustainably produced propionic acid.
Propionic acid fermentation is reported by several Propionibacterium species under anaerobic conditions. However, propionic acid fermentation is currently facing a number of challenges including:
low growth rate, product inhibition, and expensive downstream processing for high quality products. Recently progress has been made in optimising fermentation conditions and
in developing genetically-engineered microbes to increase yields and reduce by-product formation.