Enhanced Saccharification by Trichoderma reesei Expressing a β-Glucosidase from Magnaporthe oryzae

Abstract

A his₇-tagged β-glucosidase from Magnaporthe oryzae (MoCel3A) was expressed under the control of a cellobiohydrolase I (cbh1) promoter in Trichoderma reesei. Accumulation of extracellular his₇-tagged MoCel3A and glucose production were evaluated during growth on a variety of substrates. Enzyme preparations obtained from the recombinant T. reesei strain grown in the presence of cellulose produced more his₇-tagged MoCel3A, exhibited greater hydrolytic activity towards pNPG and produced more glucose from PSC, cellulose, rice straw and laminarin than the wild type parent. These results indicate that expression of his₇-tagged MoCel3A enhanced glucose production not only from β-1,4-glucan but also from β-1,3-glucan. More his₇-tagged MoCel3A accumulated when the recombinant strain was grown in the presence of cellooligosaccharides with various degrees of polymerization. Interestingly, accumulation of his₇-tagged MoCel3A was highly enhanced by growth on laminarioligosaccharides. An active enzyme preparation was obtained from the recombinant strain grown on rice straw, an inexpensive and renewable substrate.