Enhancing Enzymatic Activity and Stability of Crude Laccase Through Encapsulation in Gelatin/Chitosan Hydrogel.

Abstract

Laccase is an environmentally friendly catalyst characterized by a wide substrate spectrum and clean reaction processes. It demonstrates the ability to efficiently oxidize various pollutants, with water being the sole by-product. Consequently, laccase holds significant potential for applications in diverse fields such as papermaking, environmental protection, food processing, and bioenergy production. In this study, crude laccase produced by Schizophyllum commune was immobilized within a composite material through chemical cross-linking to enhance the enzyme's activity and stability. Free laccase was immobilized using a gelatin/chitosan (GEL/CS) hydrogel, and the conditions for this process were optimized. Enzymatic properties of immobilized laccase (GEL/CS-laccase) were investigated to assess its potential applications. Results indicated that the maximum laccase activity by Schizophyllum commune reached 343.9 U·mL^- 1 on day 6. Following optimization, GEL/CS-laccase achieved an activity recovery of 33.9% and an activity of 113.8 U·g^- 1. Compared with free laccase, GEL/CS-laccase shows better adaptability to pH and temperature. Furthermore, GEL/CS-laccase demonstrates moderate reusability and excellent long-term storage stability: its activity remains above 34.7% after 5 cycles and exceeds 52.9% following 180 days of storage at -80 °C and vacuum. This study has developed an efficient enzyme immobilization method, enhancing its stability and operability, and laying a solid foundation for the practical application of laccase.