(191ab) Semi-Continuous Fermentation of Acetic Acid By Mutant of Acetobacter Pasteurianus

Acetic acid, as the main component of vinegar, is used as acidifying agent, flavoring agent and spice in the food industry. It is widely used in the production of anhydride acetic acid, vinyl acetate, acetate fiber, metal acetate, acetic ester and other chemicals. Although there are many methods of producing acetic acid, the biological method is the only method to produce acetic acid used in the food industry. Acetobacter pasteurianus is the main species used in vinegar fermentation in China. However, the yield by them is not high, and the stain is unstable. In order to improve the yield of acetic acid, in this study, a mutant Acetobacter pasteurianus YHL3 screened by UV from Acetobacter pasteurianus CICC 20001 was selected. Its semi-continuous fermentation process was optimized. With the optimized medium, the highest acetic acid production of 75.24 g/L was obtained in a 7-L bioreactor in four repeated batches.

The mutagenic mechanism of Acetobacter pasteurianus YHL3 was also analyzed. The tolerance test results with YHL3 and CICC 20001 showed that with the high alcohol content, ADH and ALDH with YHL3 were 5.96±0.26 U/mg and 4.82±0.22 U/mg, respectively, which were significantly higher than those of CICC 20001 (4.78±0.28 U/mg and 4.12±0.24 U/mg, respectively). With the high acid, ADH and ALDH with YHL3 were 6.08±0.18 U/mg and 5.47±0.16 U/mg, respectively. Which were also higher than those of CICC 20001 (5.66±0.16 U/mg and 4.87±0.12 U/mg, respectively). According to the metabolic pathway network analysis of Acetobacter pasteuriens, it was found that the enzyme system of YHL3 in ethanol oxidative respiratory chain was better than that of CICC 20001. The above results demonstrated the feasibility of industrial production of high-concentration acetic acid in vinegar fermentation.