Genetic Engineering of Trichoderma reesei for Biomass Hydrolysis

The filamentous fungus Trichoderma reesei, a potent cellulase producer, is the most-studied cellulolytic fungus. This fungus is an efficient cell factory for the production of plant biomass-degrading enzymes, which can be used in the bioproduction of value-added substances such as bioethanol, as well as in a broad range of other applications. Therefore, many researchers have focused on developing new strains of T. reesei for improving specific capabilities, such as the production of glycosidase enzymes, and enhancing the composition of the secreted enzymes by the expression of heterologous glycosyl hydrolases. These studies have used various molecular biological techniques for strain modification, leading to several discoveries. In this chapter, various aspects involved in the advancement of genetic engineering in T. reesei, including transformation techniques, selectable markers, and gene promoters for expressing critical genes, are summarized and discussed. Especially, examples of applications of genome-editing techniques that have enabled remarkable progress in recent years in strain development have been included. In addition to genetic engineering, morphology in the cultivation of filamentous fungi and the possibility of coculture of T. reesei with other fungi for the production of effective plant biomass-degrading enzyme cocktails are explored.