Abstract: Response surface methodology was employed to find optimal fermentation conditions for immobilized Acetobacter pasteurianus cells obtained by using sodium alginate as the carrier. One-factor-at-a-time experiments were conducted to identify inoculum amount, initial alcohol concentration and temperature as main affecting factors of acid production. On the basis of a three-level, seventeen-run Box-Behnken experimental design, a quadratic regression model equation describing acid production as a function of the three selected variables was established. The results indicated that the optimal conditions for acetic acid fermentation were inoculum amount of 7.88 g/100 mL, initial alcohol concentration of 4.63%, and fermentation temperature of 32 ℃. Under the optimized fermentation conditions, the yield of total acids was 3.51 g/100 mL, which was close to the theoretical yield of 3.56 g/100 mL. Therefore, response surface methodology can provide the optimal fermentation condition of immobilized Acetobacter aceti for practical applications due to its reliability.

Key words: immobilization, Acetobacter aceti, response surface methodology, Box-Behnken design, optimization