Study on Synthesis of Propionic Acid by Microorganism Oxidation of Propanol

【Objective】This paper discussed a method for the synthesis of propionic acid by microbial oxidation of propanol, using propanol as substrate.By comparing the acid production of the Gluconobacter oxydans, Acetobacter pasteurianus and Vinegar bacteria ,the three strains rich in alcohol oxidase and aldehyde oxidase system,select the strain with higher acid production and optimize fermentation conditions to obtain ideal fermentation results.【Methods】All three strains used different substrate concentrations for the initial fed-batch fermentation ,Select Vinegar bacteria for Fermentation and optimized fermentation conditions，The optimization method is to adjust the substrate ratio of 1:2 (glucose:propanol) to 2:1 (glucose:propanol), and add 60% concentration of glucose in the fed-batch process, and the ratio of the feed (glucose:propanol) is also 2:1.【Results】The fermentation period of Gluconobacter oxydans was 60h, the conversion rate was 14.84%, the propionic acid yield was 7.55 g/L, and the yield was 0.126 g/L/h; The fermentation period of Acetobacter pasteurianus is 98h, the conversion rate can reach 42.13 % at 30h, the yield of propionic acid can reach 18.09 g/L, and the yield is 0.185 g/L/h; The fermentation period of Vinegar bacteria is 102h, the propionic acid yield can reach 21.13g/L at 78h, the conversion rate is 26.42%, and the yield is 0.271 g/L/h, but when the fermentation period was 42h, the yield was only 1.3 g/L, and the rate was only 0.03 g/L/h. In the optimized scheme, in the same fermentation period, the yield was 16.13 g/L, and the rate was 0.38 g/L/h, an increase of 11.67 times.【Conclusion】All three strains can use propanol as a substrate to produce propionic acid, and 1 has the highest yield. When the initial fermentation substrate of 1 increases the glucose concentration and when glucose is fed during the fermentation process, Glucose provides NADH for the conversion of propanol and propionic acid, and propionic acid production is increased.