Immobilization of β-glucosidase on Eupergit C for Lignocellulose Hydrolysis

Abstract

β-Glucosidase is frequently used to supplement cellulase preparations for hydrolysis of cellulosic and lignocellulosic substrates in order to accelerate the conversion of cellobiose to glucose. Typically, commercial cellulase preparations are deficient in this enzyme and accumulation of cellobiose leads to product inhibition. This study evaluates the potential for recycling β-glucosidase by immobilization on a methacrylamide polymer carrier, Eupergit C. The immobilized β-glucosidase had improved stability at 65 °C, relative to the free enzyme, while the profile of activity versus pH was unchanged. Immobilization resulted in an increase in the apparent K_m from 1.1 to 11 mm and an increase in V_max from 296 to 2430 μmol mg⁻¹ min⁻¹. The effect of immobilized β-glucosidase on the hydrolysis of cellulosic and lignocellulosic substrates was comparable to that of the free enzyme when used at the same level of protein. Operational stability of the immobilized β-glucosidase was demonstrated during six rounds of lignocellulose hydrolysis.