Immobilization of β-glucosidase and β-xylosidase on inorganic nanoparticles for glycosylated substances conversion.

There are abundant glycosylated substances such as cellulose, hemicellulose, and phytochemical glycosides in plants, which could be converted into functional chemicals such as monosaccharides, oligosaccharides, and bioactive aglycones by cleavage of glycosidic bonds using glycoside hydrolases (GHs). Among those GHs, β-glucosidase and β-xylosidase are the rate-limiting enzymes for degrading cellulose and hemicellulose, respectively, and can convert a variety of glycosylated substances. These two enzymes play important roles in the high value use of plant resources and have great potential applications. However, the fragility of enzymes suggests there is an urgent need to improve the activity, stability and reusability of GHs under industrial conditions. Enzyme immobilization is an efficient approach to meet the need. Inorganic materials are preferred carriers for enzyme immobilization, since they possess high surface area, pore size, stability and long service life. Recently, many reports have showed that GHs immobilized on inorganic materials exhibit potential applications on industry and will benefit the process economy. The present review provides an overview of these reports from the perspectives of materials, strategies, activities, stability and reusability, as well as an insight into the related mechanisms, with a view to providing a reference for the GHs immobilization and their applications.