An overview on the biotechnological production of propionic acid: From up to downstream processes

Abstract

The increasing demand for propionic acid production and wide applications in several industries especially in food (as preservative and satiety-inducer) has led looking for biosynthesis of this acid with a low total cost. This paper gives an overview on biotechnological aspects of propionic acid production and moves on to the introducing of Propionibacterium as the most popular one. Also all process variables influencing on production yield, different simple and complex carbon sources, metabolic pathway of production, engineered mutants with increased productivity, and modified tolerance against high concentrations of acid have been described. Then possible methods of extraction and analysis of this organic acid as well as several applied bioreactors, the different culture systems and substrates have been introduced. It can be concluded maximum biomass and propionic acid production may be achieved by using metabolic engineering microorganisms, and study on the most significant factors influencing on yield. To date, the maximum reported yield for propionic acid (PA) production is 0.973 g.g^-1 obtained from cultivation of Propionibacterium acidipropionici in a three-electrode amperometric culture system with medium containing 0.4 mM cobalt sepulchrate. Also, the best promising substrate for PA bioproduction may be achieved by glycerol as a carbon source in an extractive continuous fermentation. Simultaneous production of propionic acid and vitamin B₁₂ is suggested, and finally limitations and strategies for competitive microbial production with respect to chemical process from economical view of point are proposed and presented. Finally some future trends for bioproduction of propionic acid is suggested.