Immobilization kinetics of CMCase and β-glucosidase from Aspergillus niger in calcium alginate beads

Carboxymethyl cellulase (CMCase) and β-glucosidase were produced by Aspergillus niger using mango peel residue as substrate and immobilized on calcium alginate beads through entrapment technique. The catalytic properties of the immobilized CMCase and β-glucosidase were compared to free enzyme. The enzyme efficiency of the immobilized CMCase and β-glucosidase were found to be 89.52 and 86.61%, respectively. Maximum immobilization efficiency was achieved on beads formed by 5% (m/v) of sodium alginate and bead size of 2 mm and 1.5 mm, for CMCase and β-glucosidase, respectively. The immobilized enzyme showed higher stability over a wider pH and temperature range. Metal ions, viz. Cu 2 +, Mo 2+ , Mn 2+ , Ca 2+ , B 3+ , Zn 2+ , Mg 2+ and Fe 2+ showed positive effect for immobilized β-glucosidase activity, while Mg 2+ on immobilized CMCase activity. The immobilized enzymes could express 20-25% relative enzyme activity even after 4 th repeated use. Immobilization improved the thermal stability over the free enzyme and affected the enzyme kinetic constants, viz. K M , V max and activation energy.