Abstract: Response surface analysis was used to optimize the fermentation medium for chitosanase production by Aspergillus fumigatus K1. In the first step,fractional factorial design was adopted to screen out the important factors affecting chitosanase production,which were beef extract and CaCl2. The path of the steepest ascent was utilized to approach the optimal region of the chitosanase production. At last,the optimal composition of the fermentation medium was obtained by central composite design and response surface analysis for chitosanase production by Aspergillus fumigatus K1. The optimal culture medium (%,W/V) consisits of : chitosan 1.5,beef extract 2.1,KH2PO4 0.1,MgSO·4 7H2O 0.1,CaCl2 0.4 and Tween 0.1. After optimization,the yield of chitosanase production is 44.24 U/ml,2.4 times higher than that in the original medium.

Key words: chitosanase, response surface analysis, Aspergillus fumigatu, soptimization