Highly enhanced activity and stability via affinity induced immobilization β-glucosidase from Aspergillus niger onto amino-based silica for the biotransformation of ginsenoside Rb1

In this study, an enzyme immobilization method for the effective biotransformation of ginsenoside Rb1 to impart activity and stability was developed. Using a hydrolase enzyme model, beta-glucosidase from Aspergillus niger, immobilization within chemically affinity-linked amino-based silica provided an immobilization efficiency 5.86-fold higher than that of free enzyme. Compared with the free enzyme, the immobilized enzyme functioned optimally at a wider pH range and had higher thermostability. The optimum pH for the free and immobilized enzymes was 5.5. The optimal reaction temperature of the immobilized enzyme was 45 degrees C, which was 5 degrees C higher than that of the free enzyme. The Michaelis constant (K-m) values before and after immobilization were 0.482 mmol.L-1 and 0.387 mmol.L-1, respectively. The catalytic rate (K-cat) for the immobilized and free enzymes was 22.269 mmol.L-1 and 8.800 mmol.L-1, respectively, and the catalytic efficiency (K-cat/K-m) activity of the immobilized enzyme was 3.30-fold higher than that of the free enzyme. The immobilized enzyme could preserve 97 % of the activity after 45 cycles of repeated use. The high catalytic activity and significant operational stability are beneficial for industrial applications. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study developed an enzyme immobilization method for the efficient biotransformation of ginsenoside Rb1, resulting in increased activity and stability. The immobilized enzyme showed higher immobilization efficiency, a wider optimal pH range, higher thermostability, and greater catalytic efficiency compared to the free enzyme.