Induction and Optimization of Chitosanase Production by Aspergillus fumigatus YT-1 Using Response Surface Methodology

H. Zhang and W. Zhang

Abstract
With the use of a mixture of shrimp shell powder and wheat bran as carbon sources in the medium, statistical methods including Plackett-Burman design (PBD), steepest ascent method and Central composite design (CCD) were applied to optimize chitosanase production by a newly isolated Aspergillus fumigatus YT-1 under submerged fermentation. Significant factors for chitosanase production including (NH4)2SO4, shrimp shell powder and MgSO4 · 7H2O were screened. Maximum chitosanase activity (21.85 U mL–1) was achieved under the optimized conditions [(NH4)2SO4 5.05 g L–1, shrimp shell powder 23.40 g L–1, MgSO4 · 7H2O 0.88 g L–1]. According to maximum chitosanase activity (5.29 U mL–1) which was obtained under unoptimized conditions, optimization resulted in an overall 3.13–fold enhancement in chitosanase activity. The optimal temperature and pH for chitosan hydrolysis were 60 °C and pH 4.8, respectively.

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Keywords
Aspergillus fumigatus, chitosanase, optimisation, shrimp shell powder, response surface methodology