Efficient preparation of soluble inducer for cellulase production and saccharification of corn stover using in-house generated crude enzymes

Abstract

Although high-level cellulase production by Trichoderma reesei from lignocellulosic biomass in biorefinery has been widely studied, more efficient and economic hydrolysis is required to reduce the production cost. In this study, the recombinant T. reesei PB-3 strain overexpressing the β-glucosidase gene was used to achieve a high cellobiase activity of 78.09 CBU/mL using glucose as the sole substrate using fed‑batch fermentation. The obtained crude cellobiase was then used for transglycosylation, and kinetic studies showed that high concentration of glucose as the substrate is required for the reaction. We found that remarkably shorter transglycosylation time (2 h) than that was commonly reported (72 h), was sufficient when using the optimised conditions. Subsequently, the crude cellobiase from T. reesei PB-3 strain was also used to blend with the crude cellulase produced by T. reesei Rut C30 for hydrolysing corn stover, and a high glucose yield (97.08%) was achieved. The strategy developed in this work benefits reduction of cellulase production cost through in-house cellulase production for both inducer preparation and hydrolysis of the biomass.