Abstract
The aim of this work was to genetically modify the carbon catabolite
repression of Trichoderma reesei to obtain mutant strains derepressed in
cellulase production. Several genes coding for regulators of cellulase
expression have been isolated and characterized from T. reesei including the
cre1 gene mediating the carbon catabolite repression in the presence of
glucose. Glucose repression has been shown to occur upon binding of CREI
protein to specific sequences in the promoter of the major cellulase gene
cbh1. CREI target sequences have also been identified in the promoter regions
of other cellulase and hemicellulase genes such as e.g. cbh2 and xyn1.
The CREI protein of T. reesei is similar to many other fungal proteins
mediating glucose repression. It was recently shown, however, that a truncated
form of CREI (cre1-1) present in the hypercellulolytic T. reesei strain
Rut-C30 is responsible for derepression of (hemi)cellulase gene expression on
glucose-containing media.
Therefore, to study the effect of cre1 on cellulase and hemicellulase
expression, the wild type cre1 gene present in the T. reesei strain QM6a was
either replaced by the "Rut-C30 -type" truncated cre1 -1 gene or completely
removed. Bioreactor cultivations on lactose and glucose media were carried out
with these cre1-1 and delta-cre1 mutant strains and analysed for cellulase
and hemicellulase production. Northern analysis indicated remarkably higher
expression levels of several (hemi)cellulase genes in both mutant strains on
lactose when compared to the non-modified parent strain. In accordance,
20-fold higher cellobiohydrolase and endoglucanase activities and almost
10-fold higher xylanase activities were detected in the lactose culture medium
of mutant strains.
Original language | English |
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Pages | 133 |
Publication status | Published - 2004 |
MoE publication type | Not Eligible |
Event | 7th European Conference on Fungal Genetics - Copenhagen, Denmark Duration: 17 Apr 2004 → 20 Apr 2004 |
Conference
Conference | 7th European Conference on Fungal Genetics |
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Country/Territory | Denmark |
City | Copenhagen |
Period | 17/04/04 → 20/04/04 |