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Fig. 6 | Biotechnology for Biofuels

Fig. 6

From: Upgrading of efficient and scalable CRISPR–Cas-mediated technology for genetic engineering in thermophilic fungus Myceliophthora thermophila

Fig. 6

Cellulolytic phenotype analysis of eight deletion mutants and wild-type strain (WT). a Schematic model illustrating the coordinated action of cellulolytic factors under cellulose induction. Under cellulose conditions, the positive regulators CLR-1, CLR-2, and XYR-1 have been identified as key transcription factors regulating cellulose degradation. Preferred carbon sources such as glucose activate the essential transcription factor CRE-1, which represses the expression of cellulase genes, a phenomenon called carbon catabolite repression (CCR). Lack of the major intracellular β-glucosidase GH1-1 facilitates the accumulation of intracellular cellobiose, which can trigger signaling cascades that include expression of cellulase genes repressed by CRE-1 and activated by CLR-1/2 and XYR-1. The newly identified regulators RES-1, HCR-1, RCA-1, AP-3, the major secreted protease ALP-1, and protein kinase PRK-6 were shown to negatively affect cellulase production. b Secreted protein production of all strains after 6-days cultivation in 2% Avicel medium supplemented with 0.75% yeast extract. Genotype of the eight deletion mutants as compared to the WT strain. The 11 target genes edited by our CRISPR–Cas12a system included cre-1, res-1, gh1-1, neo, alp-1, rca-1, xyr-1, hcr-1, bar, ap-3 and prk-6. The symbol of +, or − or OE indicated the target gene is present, or deleted or overexpressed. c, d Assays for CMCase and xylanase activity in the eight deletion mutants and WT strains in 2% Avicel plus 0.75% yeast extract after 6 days culture. Bars marked by asterisks in each group differ significantly from the unmarked bars (Tukey’s HSD, p < 0.001). Error bars represent SD from three replicates

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