Performance of β-galactosidase pretreated with lactose to prevent activity loss during the enzyme immobilisation process

In this study, Kluyveromyces lactis beta-galactosidase was pretreated with lactose to prevent loss of activity during the immobilisation process, and glutaraldehyde was used as a linker to immobilise beta-galactosidase on the surface of a silica gel. The pretreatment of beta-galactosidase strongly improved its activity after immobilisation. Specifically, the activity of pretreated immobilised beta-galactosidase was 2.6 times greater than that of non-pretreated immobilised beta-galactosidase. The optimal temperature, pH and ionic strength of buffer for pretreated immobilised beta-galactosidase were 37 degrees C, pH 7.5 and 20 mM potassium phosphate buffer, respectively. These values were shifted by 5 degrees C and pH by 0.5 when compared to the soluble beta-galactosidase. Moreover, the pretreated immobilised beta-galactosidase showed a better reusability than did non-pretreated immobilised beta-galactosidase, with 63.9% of its original activity being retained after 10 reuses. (C) 2010 Elsevier Ltd. All rights reserved.