Enhanced glucose-1-phosphate production from corn stover using cellulases with reduced β-glucosidase activity via Trbgl1 gene knockout in Trichoderma reesei Rut C30

The scarcity of cellulases with low β-glucosidase activity poses a significant technological challenge in precisely controlling the partial hydrolysis of lignocellulose to cellobiose, crucial for producing high-value chemicals such as starch, inositol, and NMN. Trichoderma reesei is a primary strain in cellulase production. Therefore, this study targeted the critical β-glucosidase gene, Trbgl1, resulting in over an 86 % reduction in β-glucosidase activity. However, cellulase production decreased by 19.2 % and 20.3 % with lactose or cellulose inducers, respectively. Notably, transcript levels of cellulase genes and overall yield remained unaffected with an inducer containing sophorose. This indicates that β-glucosidase BGL1 converts lactose or cellulose to sophorose through transglycosylation activity, inducing cellulase gene transcription. The resulting enzyme cocktail, comprising recombinant cellulase and cellobiose phosphorylase, was applied for corn stover hydrolysis, resulting in a 24.3 % increase in glucose-1-phosphate yield. These findings provide valuable insights into obtaining enzymes suitable for the high-value utilization of lignocellulose.