Mechanism for reversible inactivation of immobilized β-galactosidase from Bacillus circulans during continuous production of galacto-oligosaccharides

The specific activity-dependent stability of the immobilized β-galactosidase-2 (β-d-galactoside galactohydrolase, EC 3.2.1.23) from Bacillus circulans during the continuous production of galactooligosaccharides from lactose was studied. This was done by measuring the elution pattern of saccharides from the various immobilized Merckogel (controlled pore silica gel) columns and the amount of saccharides remaining in the gel. It was suggested that oligosaccharides produced were trapped inside the three dimensional enzyme aggregate with the immobilized enzyme having a specific activity of 240 units/g of wet gel, causing gradual inactivation, while the immobilized enzyme with 15 units/g of wet gel was stable since the oligosaccharides were not accumulated.