MICROBIAL HYDROLASES IMMOBILIZED ON POROUS MATRICES

Abstract

Starch degrading enzymes are used as feed additives to increase the digestibility of corn meal based diet in livestock and poultry. To be efficient, these enzymes have to present a good activity and stability. Immobilization by physical bonding o f enzymes on a porous support is a simple and efficient method to preserve enzyme molecules in an active form and retain their activity for a period o f time. The aim o f this study was to stabilize an enzymatic preparation with amylase activity produced by a native strain o f Bacillus amyloliquefaciens in submerged culture. The immobilization technique used was physical bonding on a porous ceramic support. The enzymatic preparation with amylase activity was used in immobilization in a liophylized form. By using the same method we immobilized also a purified Aspergillus niger amylase. For both enzymes, the optimal temperature and pH o f the native and immobilized enzymes did not vary significantly. At temperature and pH values lower than the optimum, the relative activities have been higher for the immobilized Bacillus amyloliquefaciens enzyme compared to the native one. The immobilization has led to an enzymatic compound with stability at pH 3 and 37°C and in time higher than that o f the free one.

Keywords

• feed enzymes
• amylase
• bacillus amyloliquefaciens
• aspergillus niger
• stabilization
• physical bonding