Bacillus cereus TKU006所生產幾丁質分解酵素及其他抗氧化物質之研究

Abstract

The purpose of this thesis is to study the production of chitinolytic enzymes and other antioxidants from Bacillus cereus TKU006. The optimum culture conditions for chitosanase and other antioxidants production were composed of 1% squid pen powder, 0.1% K2HPO4, 0.05% MgSO4．7H2O shaken at 25℃ in 100 mL of liquid medium in an Erlenmeyer flask (250 mL) for 3 days and 25 mL of liquid medium for 2 days, respectively. The optimum culture carbon/nitrogen source for chitinase production was 2% shrimp head powder incubated for 2 days. A chitinase and a chitosanase were purified by chromatography procedures of ion exchange and gel filtration. The molecular mass of the chitinase and chitosanase determined by SDS-PAGE were approximately 39 kDa and 44 kDa, respectively. The chitinase was completely inactivated by Fe2+, and the chitosanase was completely inactivated by Fe2+ and Cu2+. The optimum temperature, optimum pH, thermal stability and pH stability of chitinase were 60℃, pH 5, ≦50℃, pH 2-8 . The optimum temperature, optimum pH, thermal stability and pH stability of chitosanase were 60℃, pH 7, ≦50℃, pH 3-10. After squid pen powder fermented, the antioxidant properties by the assays of radical scavenging, metal chelating, reducing power and total phenolic content were reached at 75%, 97%, 441 μg/mL cysteine equivalent and 815 μg/mL gallic acid equivalent, respectively. Correlation between DPPH scavenging ability and total phenolic content were r=0.92.