Replacement of the carbon catabolite regulator (cre1) and fed-batch cultivation as strategies to enhance cellulase production in Trichoderma harzianum

Abstract This work focused on mitigating carbon catabolic repression (CCR) and increasing cellulase production in Trichoderma harzianum based on the cre1 deletion. The CRE1 protein (encoded by cre1) has been described as a cellulase transcriptional repressor in various cellulotic fungi, but has not been investigated in T. harzianum. We constructed ∆cre1 T. harzianum by replacing the cre1 gene with the amdS gene from Aspergillus nidulans. Quantitative PCR analysis of some Cazymes genes showed that CRE1 acts positively on gh61, bgl1 and xyn2. The fed-batch strategy using hydrothermal sugarcane bagasse by the ∆cre1_Th15 produced a constant rate of FPase under glucose influence, suggesting that the knockout of the carbon catabolite regulator improved the glycoside hydrolases (FPase 1.96 ± 0.32 IU/mL; β-glucosidase 5.67 ± 0.28 IU/mL and xylanase 327. 26 ± 14.25 IU/mL), so that this strain can be used for biorefinery purposes.