Improving the stability of cellulase by immobilization on modified polyvinyl alcohol coated chitosan beads

The application of cellulases in various industries demands highly stable enzymes, able to perform at extreme pH values and temperatures. In this study, improving the stability of the acid cellulase in the neutral pH range was aimed. For this purpose, modification planned to be done on polyvinyl alcohol (PVA) by maleic anhydride in contrast to many studies in which enzyme was modified. The chitosan beads were coated with polyanionic modified PVA and cellulase was immobilized on the modified PVA coated chitosan beads. As a result of this modification, the pH optimum of enzyme shifted from pH 4.0 to 7.0 and the immobilized cellulase beads showed better pH stability than free enzyme at neutral pH range. The activity yield of the immobilized cellulase was found to be as 87%, and it was found no change of the optimum temperature after immobilization. (c) 2006 Elsevier B.V. All rights reserved.