Abstract

beta-Galactosidase from Bacillus circulans was immobilized on hierarchical macro-mesoporous silica by multipoint covalent attachment by formation of Schiff bases between enzyme and support. The enzyme was effectively immobilized with high yields (around 60-80%) and expressed activity (around 50-80%) depending on the concentration of aldehyde groups in the carrier. Immobilization of beta-galactosidase in chemically modified silica conferred excellent thermal stability to the biocatalyst and enzyme leaching was completely avoided. The effect of the concentration of functional groups in the silica surface was studied on the activity and thermal stability of the biocatalyst. The best hybrid catalyst was 370-fold more stable than the soluble enzyme at pH 6 and 55 degrees C. (c) 2012 Elsevier B.V. All rights reserved.