Purification and Characterization of Protease and Chitinase from Bacillus cereus TKU006 and Conversion of Marine Wastes by These Enzymes

摘要

A chitinase- and protease-producing bacterium was isolated and identified as Bacillus cereus TKU006. The better condition on our tests for protease and chitinase production was found when the culture was shaken at 25A degrees C for 2 days in 25 mL of medium containing 2% shrimp shell powder (w/v), 0.1% K2HPO4, and 0.05% MgSO4 center dot 7H(2)O. The molecular masses of TKU006 protease and chitinase determined by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis were approximately 39 and 35 kDa, respectively. The optimum pH, optimum temperature, pH stability, and thermal stability of TKU006 protease and chitinase were 9, 50A degrees C, 3-11, 50A degrees C and 5, 40A degrees C, 3-11, 60A degrees C, respectively. TKU006 protease was inhibited completely by EDTA, indicating that the TKU006 protease was a metalloprotease. The TKU006 protease and chitinase retained 61%, 60%, 73%, and 100% and 60%, 60%, 71%, and 96% of its original activity in the presence of 2% Tween 20, 2% Tween 40, 2% Triton X-100, and 1 mM SDS, respectively. The antioxidant activity of TKU006 culture supernatant was determined through the scavenging ability on DPPH with 70% per milliliter. In conclusion, the novelties of the TKU006 protease and chitinase include its high stability to the surfactants and pH. Besides, with this method, we have shown that marine wastes can be utilized to generate a high-value-added product and have revealed its hidden potential in the production of functional foods.