Enhancing Cellulase and Hemicellulase Production in Trichoderma orientalis EU7-22 via Knockout of the creA

The role of the transcription factor creA- mediating carbon catabolite repression in Trichoderma orientalis EU7-22 was investigated for cellulase and hemicellulase production. The binary vector pUR5750G/ creA :: hph was constructed to knock out creA by homologous integration, generating the Δ creA mutant Trichoderma orientalis CF1D. For strain CF1D, the filter paper activities (FPA), endoglucanase activities (CMC), cellobiohydrolase activity(CBH), β-glucosidase activity (BG), xylanase activity (XYN), and extracellular protein concentration were 1.45-, 1.15-, 1.71-, 2.51-, 2.72, and 1.95-fold higher in inducing medium and were 6.41-, 7.50-, 10.27-, 11.79-, 9.25-, and 3.77-fold higher in glucose repressing medium, respectively, than those in the parent strain after 4 days. SDS–PAGE demonstrated that the extracellular proteins were largely secreted in the mutant CF1D. Quantitative reverse-transcription polymerase chain reaction indicated that the expressions of cbh1 , cbh2 , eg1 , eg2 , bgl1 , xyn1 , and xyn2 were significantly increasing for the mutant CF1D not only in the inducing medium but also in the repressing medium. Those results indicated that creA was a valid target gene in strain engineering for improved enzyme production in T. orientalis .