Covalent Immobilization of α-Amylase from Thermophilic Geobacillus sp. TF14 on Chitosan Beads

Abstract

In this study, α-amylase formerly purified from Geobacillus sp. TF14 strain was covalently immobilizedonto chitosan beads. Chitosan beads were prepared by dissolving chitosan powder in 5% acetic acid solutionand by addition dropwise to 1 M NaOH solution. The consisted beads were washed to remove excessiveamount of NaOH. Immobilization was carried out in two steps. Firstly, chitosan beads were activated byreacting with 2.5% Glutaraldehyde solution. Next, activated chitosan beads were mixed with enzymesolution to complete immobilization. Biochemical characterization of immobilized α-amylase was alsocarried out. It was found that immobilized α-amylase achieved maximum activity at pH 9.00 and theenzyme was quite stable at this pH over a period of 48 h. Temperature optimum of the enzyme wasdetermined as 95 °C. It was also determined that the enzyme protected 50% of its initial activity afterincubation of 48 h at this temperature. While Mn2+, Co2+ and EDTA almost completely inhibited theenzyme, other metal ions showed inhibitory effects at different ratio. In the presence of some detergentsthe enzyme conserved its initial activity. It can be concluded that the immobilized α-amylase may findapplication in many fields of starch based industries.