Abstract:

Purpose: To optimize the fermentation conditions for chitinase inhibitor production by Streptomyces sp A0901
by applying response surface analysis. Methods: Firstly, the optimum carbon source and nitrogen source were confirmed
as soluble starch and potassium nitrate respectively based on the results of single-factor experiments. Then, a two-level
Plackett-Burman factorial design was used to evaluate the influence of seven factors including medium components and
fermentation conditions on the production of chitinase inhibitor. Among them, three important factors including soluble
starch, ZnCl2 and incubation temperature were screened. Further, the steepest ascent path was utilized to determine the
optimal region for chitinase inhibitor production．Results: The optimal medium composition and fermentation conditions
were determined by central composite design and SAS regression analysis to be 3.76 g of soluble starch, 0.05 g of NaCl, 0.1 g
of KNO3, 0.05 g of K2HPO4·3H2O, 0.04 g of MgSO4?7H2O, 0.024 g of ZnCl2, and 0.001 g of FeSO4·7H2O per 100 mL of
culture medium with an initial pH of 6 and fermentation at 28.54 ℃ at a shaker speed of 250 r/min. Conclusions: Under
the optimized culture conditions, the inhibition of chitinase by fermented broth of Streptomyces sp. A0901 reached 67.58%,
36.8% higher than before the optimization.

Key words: chitinase inhibitor, food preservation, response surface methodology, fermentation conditions