Abstract:The optimal cultural conditions for protease production by Bacillus subtilis UMN-26 with the crab shell powder as the main composition of culture medium was studied，which may lay the foundation for deproteinization of crab cells with microbiological fermentation method.Single factor tests and response surface methodology were adopted to optimize the fermentation conditions of the crab shell powder culture medium，with the proteinase activity of the fermentation supernatant as an index.The results showed that the optimized conditions were：crab shell powder concentration was 5.5%，sucrose concentration was 11.81%and initial pH 7.27.And optimized fermentation conditions were：cultural temperature was 37℃，rotational speed was 200 r/min and time was 108 h.The protease enzyme activity of fermentation supernatant reached 1 465.86 U/mL，7.86 times than the former，and the rate of deproteinization was 70.71%.