Ultrasound-Assisted Intensification of β-Glucosidase Enzyme Activity in Free and Immobilized Forms

Abstract

The focus of the current work was to enhance the productivity and activity of enzymes based on immobilization and application of ultrasound. β-Glucosidase was immobilized using a cross-linking method that was a carrier-free approach. Parameters such as the ammonium sulfate concentration (60–90%), glutaraldehyde concentration (0.5–1.5%), and use of bovine serum albumin (BSA) were optimized during the preparation of cross-linked enzyme aggregates (CLEAs). The optimum temperature (50 °C) and pH (5) were observed to be the same for both the soluble and immobilized enzymes in CLEAs. Use of 1% glutaraldehyde concentration gave a recovery of 30%, but after adding BSA (0.3 mM) the recovery enhanced to 57%. The effect of ultrasonic treatment on enzyme activity was analyzed using an ultrasonic bath with maximum activity observed at a 30% duty cycle, a 50 W power, and a treatment time of 20 min with an actual value of 9.7 U/mL, which was higher as compared to that of the untreated enzyme (8.86 U/mL). The enzyme immobilized after pretreatment with ultrasound allowed an activity recovery of 82% that was significantly higher compared to that of the untreated immobilized enzyme. The immobilized enzyme prepared with a pretreated enzyme exhibited higher reusability and thermal stability as compared to the enzyme immobilized with the untreated enzyme. Overall, an effective method for immobilization of enzymes along with the use of ultrasound for intensification was demonstrated.