Immobilization of Aspergillus oryzae tannase and properties of the immobilized enzyme

摘要

Tannase enzyme from Aspergillus oryzae was immobilized on various carriers by different methods. The immobilized enzyme on chitosan with a bifunctional agent (glutaraldehyde) had the highest activity. The catalytic properties and stability of the immobilized tannase were compared with the corresponding free enzyme. The bound enzyme retained 20.3% of the original specific activity exhibited by the free enzyme. The optimum pH of the immobilized enzyme was shifted to a more acidic range compared with the free enzyme. The optimum temperature of the reaction was determined to be 40 deg C for the free' enzyme and 55 deg C for the immobilized form. The stability at low pH, as well as thermal stability, were significantly improved by the immobilization process. The immobilized enzyme exhibited mass transfer limitation as reflected by. a higher apparent K_m value and a lower energy- of activation. The immobilized enzyme retained about 85% of the initial catalytic activity, even after being used 17 times.