Substrate specificity and enzyme recycling using chitosan immobilized laccase

Area of Science:

• Biotechnology
• Enzyme Engineering
• Biocatalysis

Background:

• Enzyme immobilization is crucial for industrial biocatalysis.
• Chitosan offers a biocompatible matrix for enzyme immobilization.
• Laccase is a versatile enzyme for oxidizing phenolic compounds.

Purpose of the Study:

• To immobilize laccase (Aspergillus sp.) onto chitosan via cross-linking.
• To evaluate the stability and efficiency of immobilized laccase in phenolic compound bioconversion.
• To investigate substrate specificity and enzyme reusability.

Main Methods:

• Enzyme immobilization using chemical cross-linking on a chitosan matrix.
• Bioconversion of eighteen phenol derivatives using immobilized laccase in batch reactors.
• Assessment of reaction yields, kinetics, operational stability, and enzyme recyclability.

Main Results:

• Chitosan-immobilized laccase demonstrated higher operational stability compared to physical adsorption.
• High reaction yields (>90% at 40 °C) were observed for specific phenols like 2,5-xylenol and 2,6-dimethoxyphenol (2,6-DMP).
• Enzyme reusability was achieved for 2,6-DMP bioconversion over eight batches, but not for syringaldazine.

Conclusions:

• Chemical cross-linking of laccase on chitosan provides a stable and efficient biocatalyst.
• The immobilized enzyme exhibits substrate-dependent reusability, with successful application in 2,6-DMP bioconversion.
• This immobilization strategy holds promise for sustainable bioconversion processes.