Immobilization of the alpha-amylase of Bacillus amyloliquifaciens TSWK1-1 for the improved biocatalytic properties and solvent tolerance

The alpha-amylase of Bacillus amyloliquifaciens TSWK1-1 (GenBank Number, GQ121033) was immobilized by various methods, including ionic binding with DEAE cellulose, covalent coupling with gelatin and entrapment in polyacrylamide and agar. The immobilization of the purified enzyme was most effective with the DEAE cellulose followed by gelatin, agar and polyacrylamide. The K (m) increased, while V (max) decreased upon immobilization on various supports. The temperature and pH profiles broadened, while thermostability and pH stability enhanced after immobilization. The immobilized enzyme exhibited greater activity in various non-ionic surfactants, such as Tween-20, Tween-80 and Triton X-100 and ionic surfactant, SDS. Similarly, the enhanced stability of the immobilized alpha-amylase in various organic solvents was among the attractive features of the study. The reusability of the immobilized enzyme in terms of operational stability was assessed. The DEAE cellulose immobilized alpha-amylase retained its initial activity even after 20 consequent cycles. The DEAE cellulose immobilized enzyme hydrolyzed starch with 27 % of efficiency. In summary, the immobilization of B. amyloliquifaciens TSWK1-1 alpha-amylase with DEAE cellulose appeared most suitable for the improved biocatalytic properties and stability.