Single Mutation in Transcriptional Activator Xyr1 Enhances Cellulase and Xylanase Production in Trichoderma reesei on Glucose.

To achieve cost-effective production of lignocellulolytic enzymes for biorefinery processes, engineering transcription factors represents a powerful strategy to boost cellulase and xylanase in . In this study, a novel mutation (R434L) in xylanase regulator 1 (Xyr1) was identified based on the yeast one-hybrid screening system. The point mutation was located in the middle homology region of Xyr1 with unclear functions, indicating a significant role for this domain in tuning Xyr1 transactivation. When constitutively expressed in Δ (OEX), Xyr1 led to highly improved production of both cellulases and xylanases on glucose compared with a strain similarly expressing Xyr1 (OEX). The respective 0.8- and 0.7-fold increases in extracellular pNPCase and xylanolytic activity were further verified to result from the greatly elevated transcription of major cellulase and xylanase genes in OEX. Moreover, the saccharification efficiency of corn stover with OEX enzyme cocktails was enhanced by 21% compared with that of OEX.