INTERNATIONAL JOURNAL OF PHARMACY & LIFE SCIENCES Activity and stability of immobilized alpha-amylase produced by Bacillus acidocaldarius

An isolated strain (from rice), Bacillus acidocaldarius was able to produce extracellular �-amylase.The enzyme was partially purified with 50% acetone and showed 4.3- fold purification. Amylase was immobilized on diffe rent carriers by different methods and its specific acti vity for starch hydrolysis studied. Immobilized � -amylase on glass beads (covalent binding) and cation exchange resin (ionic binding) had the highest immobilization yiel d (85.6 and 84.3%), respectively. It was further observed that, thermal and pH stabilities of immobilized enzymes were higher compared to free enzyme. The immobilized enzymes had higher K (Michaelis constant) and lower V (Maximum A rate of reaction) than the free enzyme. Activation energy (E ) of free enzyme was 2.37 Kcal/mol which was higher than the immobilized enzyme by covalent binding or by ionic binding (1.05 and 1/2 1.59 Kcal/mol), res pectively. Half life time (t ) of immobilized enzyme on glass beads was 83 min which was higher than that of immobilized enzyme on cation exchange resin (61 min). Immobilized enzyme on glass beads showed the highest operational stability for up to 8 reuses with 70% residual acti vity. On the other hand, �-amylase immobilized on cation exchange resin retained 66.2% of its original activity after 8 cycles.