IMPROVED CATALYTIC ACTIVITY OF ASPERGILLUS ORYZAEβ-GALACTOSIDASE BY COVALENT IMMOBILIZATION ON EUPERGIT CM
Y. Aslan1*, A. Y. Taher1 and İ. Cavidoğlu2
1Department of Food Engineering, Faculty of Engineering and Architecture, Siirt University, Kezer Campus, 56100, Siirt, Turkey; 2Department of Food Engineering, Faculty of Engineering, Van Yüzüncü Yıl University, Campus, 65080, Van, Turkey
*Corresponding Author’s email: email@example.com
In this study, Aspergillus oryzae β-Galactosidase (AOG) was immobilized onto Eupergit CM. By optimizing the immobilization conditions such as pH and molarity of immobilization buffer, enzyme/support ratio and duration of immobilization, 100.00% immobilization yield and 129.82% activity yield was achieved. The optimum temperature (55 °C) of free enzyme was not changed while optimum pH of free enzyme was shifted from 4.5 to 5.5 after immobilization. Kinetic constants for free and immobilized enzyme were also determined by using the Lineweaver-Burk plot. The Km values of the free and immobilized enzymes were determined to be 307.7 and 234.2 g / L respectively, while the Vmax values were determined to be 0.366 g D-Glucose / L.min and 0.415 g D-Glucose / L.min respectively. The operational and storage stabilities of immobilized enzyme were also studied. The activity of immobilized enzyme decreased to 99.3% after repeated twenty usage while decreased to 98.3% after fifteen days of storage. Further, the immobilized enzyme was used for the hydrolyzing the cow's milk lactose. By using the immobilized enzyme, the milk lactose was completely hydrolyzed in four hours. Consequently, immobilized AOGcan be used in the industrial production of lactose-free cow's milk.
Key words: Aspergillus oryzae; β-Galactosidase; covalent immobilization; Eupergit CM; lactose-free cow's milk; lactose intolerance