The potential of immobilized bacterial α-amylase on coconut coir, a smart carrier for biocatalysts

Abstract

Purified α-amylase from a soil bacterium Bacillus sp. SKB4 was immobilized on coconut coir, an inexpensive cellulosic fiber, with the cross-linking agent glutaraldehyde. The catalytic properties and stability of the immobilized enzyme were compared with those of its soluble form. The enzyme retained 97.2% of its activity and its catalytic properties were not drastically altered after immobilization. The pH optimum and stability of the immobilized enzyme were shifted towards the alkaline range compared to the free enzyme. The optimum temperature for enzymatic activity was 90°C in both forms of the enzyme. The soluble and immobilized enzyme retained 19% and 70% of original activity, respectively, after pre-incubation for 1 h at 90°C. Immobilized amylase was less susceptible to attack by heavy metal ions and showed higher K_m and V_max values than its free form. The bound enzyme showed significant activity and stability after 6 months of storage at 4°C. All of these characteristics make the new carrier system suitable for use in the bioprocess and food industries.

• α-Amylase
• immobilization
• coconut coir