Immobilized β-glucosidase on magnetic chitosan microspheres for hydrolysis of straw cellulose

β-Glucosidase immobilized on magnetic chitosan microspheres for potential recycling usage in hydrolysis of cellulosic biomass was investigated. The immobilized enzyme had an activity of 6.4 U/g support under optimized condition when using cellobiose as substrate. Immobilization resulted in less increase of the apparent Km, low drift of the optimal pH, as well as improved stability relative to the free enzyme. The immobilized β-glucosidase was applied to enzymatic hydrolysis of corn straw to produce 60.2 g/l reducing sugar with a conversion rate of 78.2% over the course of a 32-h reaction. This conversion rate was maintained above 76.5% after recycling the enzyme for use in eight batches (total 256 h), showing favorable operational stability of the immobilized enzyme.