Enhancement of glucose isomerase activity by immobilizing on silica/chitosan hybrid microspheres

• Immobilized GI supported by silica/chitosan hybrid microspheres was prepared in an easy approach through in situ encapsulation of GI in the support.
• The conversion of glucose to fructose could finish in 10 min catalyzed by immobilized GI due to reduced mass transfer resistance.
• The immobilized GI had much wider stability ranges of pH, temperature, ions, storage and operation in comparison with free GI.

Glucose isomerase (GI) plays a crucial role in the food industry as it serves as a catalyst for the conversion of glucose to fructose. Immobilized GI is often used due to increased stability as well as the expensive costs associated with free GI. In this study, GI was immobilized on silica/chitosan hybrid microspheres via simple process through in situ encapsulation. Enhanced rate of reaction was observed when the conversion of glucose to fructose was completed in 10 min catalyzed by immobilized GI because most GI was located on the shell of the support. Moreover, it was found that immobilized GI exhibited better pH, temperature, ions, storage and operation stability when compared to free GI. The relative enzyme activity was found to be above 90% with a wide pH range of 5.8–8.0, temperature range of 40–80 °C, storage range of 3 months and an increase in operation range of >15 times. Therefore, immobilized GI supported by silica/chitosan hybrid microspheres is an ideal candidate for biocatalysis.

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