Efficient hydrolysis of starch by α-amylase immobilized on cloisite 30B and modified forms of cloisite 30B by adsorption and covalent methods

In this paper, α-amylase from Bacillus subtilis was successfully immobilized on three supports. First, α-amylase was immobilized on cloisite 30B via the adsorption method. Then cloisite 30B was activated with tosyl chloride and epichlorohydrin. These activated supports were used for covalent immobilization of α-amylase, and their enzymatic activities were effectively tested in the starch hydrolysis. The results demonstrated that the specific activity of α-amylase immobilized on cloisite 30B was 2.39 ± 0.03, for α-amylase immobilized on activated cloisite 30B with epichlorohydrin was 1.96 ± 0.05 and for α-amylase immobilized on activated cloisite 30B with tosyl chloride was 2.17 ± 0.05 U mg-1. The optimum pH for the activity of free α-amylase was 7, but for α-amylase immobilized on cloisite 30B was 8, and for α-amylase immobilized on activated supports was 7.5. The immobilized enzymes had better thermal resistance and storage stability than free α-amylase, and they also showed excellent reusability.