1. Genetic Modification of Carbon Catabolite Repression in Trichoderma reesei for Improved Protein Production.
- Author
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Nakari-Setälä, Tuna, Paloheimo, Marja, Kallio, Jarno, Vehmaanpera, Jan, Penttilã, Merja, and Saloheimo, Markku
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GENE expression , *ENZYMES , *HEREDITY , *CARBON , *MICROFUNGI , *GENES , *GENETIC regulation , *MAMMAL reproduction , *INDUSTRIAL microbiology - Abstract
The cellulase and hemicellulase genes of the filamentous fungus Trichoderma reesei have been shown to be under carbon catabolite repression mediated by the regulatory gene crel. In this study, strains were constructed in which the crel gene was either completely removed or replaced by a truncated mutant variant, crel-1, found previously in the Rut-C30 mutant strain with enhanced enzyme production capability. The T. reesei transformants with either deletion or truncation of crel had clearly altered colony morphology compared with the parental strains, forming smaller colonies and fewer aerial hyphae and spores. Liquid cultures~ in a medium with glucose as a carbon source showed that the transformants were derepressed in cellulase and hemicellulase production. Interestingly, they also produced significantly elevated levels of these hydrolytic enzymes in fermentations carried out in a medium inducing the hydrolase genes. This suggests that crel; acts as a modulator of cellulase and hemicellulase gene expression under both noninducing and inducing cónditions. There was no phenotypic difference between the &rel and crel-1 mutant strains in any of the experiments done, indicating that the crel-1 gene is practically a null allele. The results of this work indicate that crel is a valid target gene in strain engineering for improved enzyme production in T. reesei. [ABSTRACT FROM AUTHOR]
- Published
- 2009
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