Biotechnological and Pharmaceutical Application of β-galactosidase Stabilized on Surface-modified Silica...

Nanoparticles used in enzyme immobilization offer a high surface area- to-volume ratio, high chemical and thermal stability, and resistance to microbial attack.

The present investigation demonstrates the immobilization of Aspergillus oryzae β- galactosidase on silica nanoparticles via covalent binding. A greater yield of enzyme immobilization (89%) was attained on the developed nanobiocatalyst.

It was observed that the immobilized and soluble enzymes had optimal pH and temperature values of 50°C and 4.5, respectively. It was monitored that at pH 4.0, soluble β- galactosidase (SβG) exhibited 59% activity. However, the immobilized enzyme showed 92% activity under identical conditions. Similarly, 41% enzyme activity was retained at 70 °C by the free enzyme. Conversely, immobilized β-galactosidase (IβG) retained 70% activity under similar experimental conditions. Additionally, it was observed that at 5% galactose concentration, IβG showed 55% activity under one hour of incubation. However, under comparable experimental conditions, SβG showed 24% activity.

It was observed that the immobilized enzyme was reusable, maintaining 90% of its activity even after five uses. The soluble enzyme demonstrated 62% and 70% lactose hydrolysis under the same conditions after 8 hours, while IβG demonstrated 74% and 85% lactose hydrolysis at 40°C and 50°C, respectively, in a controlled batch reactor experiment that was run for 10 hours.

Hence, owing to the greater reusability (90% after 5th repeated use) and excellent conversion of lactose at higher temperatures, the developed nanosupport may be used to produce lactose-free dairy products in continuous reactors on a large scale in biotechnology industries.