Immobilization of dextranase by Aspergillus penicillioides NRC 39 and its properties

Dextranase from Aspergillus penicillioides NRC 39 was immobilized using different carriers by various techniques including physical adsorption, covalent binding, ionic binding and entrapment. Immobilization of dextranase by covalent binding using 2% glutaraldehyde on prawn shell as carrier produced a high immobilization yield 87.4%. Comparison between the free and immobilized enzyme showed that immobilized enzyme on prawn shell produce highest immobilization yield at pH 6.0 and 40°C after 30 min of the reaction. Immobilized enzyme loses its activity when heated at 70°C for 40 min. The Km of free and immobilized enzyme was 15.8 and 17.4 mg/ml, respectively while V max of the free and immobilized enzyme was 28.5 and 23.8 U/mg protein, respectively.