The Studies on Protease and Immobilization of Bacillus cereus YQ-308

• Main Authors: Cheng Ching-Wen, 鄭景文
• Other Authors: Wang San-Lang
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/18181429269007798538

碩士 === 大葉大學 === 食品工程學系碩士班 === 91 === ABSTRACT Bacillus cereus YQ-308 was isolated from soils collected at central part in Taiwan. The culture supernatant has inhibitory activity to the growth of plant pathogens. Maximum protease activity was obtained when Bacillus cereus YQ-308 was grown aerobically at 25℃ for 1 day in a medium consisting 4% chitosan、0.3% lactose、0.2% polypeptone、0.1% K2HPO4、0.05% MgSO4 at pH 7. After concentration of the culture supernatant by precipitation with ammonium sulfate, a fungicide was purified by ion-exchange chromatography. The optimum pH and temperature were 9 and 50 ℃, respectively. The pH and temperature stability was analyzed and exhibited more stable at pH 5~9 and 50~60℃. Antifungal activity of the culture supernatant was found when using assay based upon inhibition of hyphal extension and spores germination of the fungal F. oxysporum. Make use of the marine wastes to produce antifungal substance was displayed powerfully inhibition on plant pathogens. Expect that the fungicide could apply to the agriculture in the future.