關鍵字：Bacillus cereus；幾丁聚醣酶；蝦殼粉 The chitosanase producing strain, Bacillus cereus TKU018, was isolated from the soil in the northern Taiwan. The optimized condition for chitosanase production were found when the culture was shaken at 37℃for 3 days in 100mL of medium contain 0.5% shrimp shell powder (SSP), 0.1 % K2HPO4 and 0.05 % MgSO4．7H2O (pH9). Two chitosanases (C1、C2) were purified by chromatography procedures of DEAE-Sepharose, Phenyl-Sepharose. The molecular mass of the C1 and C2 determined by SDS-PAGE was approximately 44 kDa and 22 kDa, respectively. C1、C2 The optimum temperature, optimum pH, thermal stability of C1 and C2 were (60℃、pH 5、<40℃、pH 5~7), (50℃、pH 7、<50℃、pH 4~7), respectively. The C1 was inactivated by Zn²+ , while the C2 was not affected；In the presence of SDS, the C1 was inactivated. C1、C2 retained 100% and 105% of its original activity in the presence of 0.5% Tween 20, respectively.
When cultured on various different concentrations of squid pen powder (SPP), the supernatant of third day have better DPPH radical scavenging activity.
