High activity cellulase production by recombinant Trichoderma reesei ZU-02 with the enhanced cellobiohydrolase production

The cbh1 strong promoter was employed to over-express the cbh2 gene for enhancing cellobiohydrolase (CBH) production in Trichoderma reesei because CBH II component has higher specific activity than CBH I and is an important component in cellulase. The recombinant plasmid pCAMBIA1300-hph-PsCT containing strong expression cassette was constructed and transformed into T. reesei via optimized Agrobacterium-mediated transformation, producing 324 positive T. reesei transformants for the two steps of screening. Ten fast-growing T. reesei transformants were selected, amongst which C10 was found to have the highest filter paper activity 28.92 ± 2.45 IU/mL, 4.3-fold higher than that of ZU-02, 6.71 ± 0.79 IU/mL. C10 also has the highest cellobiohydrolase activity 122.44 ± 7.42 U/mL, 5.4 times higher than that of ZU-02, 22.49 ± 2.27 U/mL. The cellulase from C10 performed better (93.06 ± 2.83%) than the one from ZU-02 in enzymatic hydrolysis because the exo–exo-synergism played a role.