Characterization and Application of Chitosanase from Bacillus cereus NCTU4

• Main Authors: Bor-ran Li, 李博仁
• Other Authors: Dr.Yaw-kuen Li
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/54209929239376706201

碩士 === 國立交通大學 === 應用化學系 === 89 === Although chitosanase can be produced from Bacillus NCTU4 without adding any inducers, suitable amount (500 ppm) of chitosan results in a 10 ~ 30 % higher yield of the activity. The extracellular chitosanase was purified and characterized. The monomeric enzyme is an endo-chitosanase with a molecular mass of 42 kDa, pI = 5.0. The optimal activity of the purified enzyme was at 60℃, pH = 5 ~ 6. With the presence of 5 mM divalent metal ion (Pb2+, Ba2+, Cu2+, Mn2+ and Ca2+), enzyme activity was found to enhance by a factor of 1.1 ~ 3.5-fold. Among them, Mn2+ was most effective. EDTA (5 mM) inhibited 30 % of the enzyme activity. Chitosan dimmer, trimer and tetramer were found to be the predominate end products. The catalytic reaction of the enzyme was identified as an inversion of the anomeric configuration indicating that a single step mechanism was involved. The end point of the hydrolysis depends on the temperature. Which consequently medicates the molecular structure of polysaccharide chain. Immobilization enzyme and resin-recovering system were developed to reduce chitosanase consumption. Both methods can nearly retain or recover 100 % of the activity. These processes are potentially useful in industry.