Improved yield and stability of amylase by multipoint covalent binding on polyglutaraldehyde activated chitosan beads: Activation of denatured enzyme molecules by calcium ions

Abstract In this study raw starch digesting amylase (RSDA) from Aspergillus carbonarius ( Bainier ) Thom IMI 366159 was stabilized by covalent binding on polyglutaraldehyde (PG), glutaraldehyde (G) activated chitosan beads or post immobilization cross linking of enzyme adsorbed on chitosan. Presence of Ca 2+ ions (0.5–1.5 mM) activated the PG and G derivatives but repressed the crosslinked enzyme. Optimum pH for cross linked derivative increased by 2 units but was unaltered for PG and G derivatives. Immobilized amylase exhibited improved thermal and storage stability. Immobilized derivatives had no loss of activity after 1 month storage and retained above 90% activity after 10 batch reactions of 60 min each. Immobilization successfully stabilized RSDA and immobilized enzyme from A . carbonarius can be applied in numerous industries for cheap, cost effective and environmentally friendly starch hydrolytic processes to simple sugars.