Kinetics of fermentative production of propionic acid on a range of carbon and nitrogen sources using Acidipropionibacterium acidipropionici

Propionic acid is a well-known organic acid with widespread applications in food, chemical, and pharmaceutical industries, mainly produced by Acidipropionibacterium and Propionibacterium genera. In this work, Acidipropionibacterium acidipropionici is used to produce propionic acid from a range of carbon, and nitrogen sources. Their organic acid distribution differed significantly depending on the carbon sources used. Glycerol almost completely converted to propionic acid, whereas glucose produced significant amount of by-products. The product distribution of lactate was in between those carbon sources. The simultaneous use of two different carbon sources can speed up fermentation by up to 50%. The fastest propionic acid production rate was 0.564 gPA L−1 h−1 with combined use of glycerol and lactic acid. This was faster than the rates achieved with lactic acid and glucose (0.256 gPA L−1 h−1) and glucose and glycerol (0.317 gPA L−1 h−1) combinations. The concentration of the carbon source affects the fermentation rate, as increased osmotic pressure results in decreased μmax. The addition of biotin and pantothenate increased the rate of fermentation, also preventing pyruvic acid accumulation. Glucose gave the highest biomass yield among carbon sources, and yeast autolysate resulted in the highest product formation among nitrogen sources. A. acidipropionici can use ammonia as a nitrogen source but to a limited extent. Overall, A. acidipropionici is a versatile organism with the potential for industrial production of propionic acid due to its flexibility to use a range of carbon sources alone or in combination which can be tailored to achieve the desired end product.