Cellulase productivity of Trichoderma reesei mutants developed in Japan varies with varying pH conditions.

The ascomycete Trichoderma reesei is known to produce a variety of cellulases and hemicellulases and the hyper-cellulolytic mutants of this fungus are useful as industrial cellulase producers. In Japan, PC-3-7, derived from the early mutant QM9414, is well-known as a cellulase hyperproducing mutant. In addition to the productivity of enzymes, the composition of secreted enzymes greatly influences biomass saccharification.

Engineering of the Trichoderma reesei xylanase3 promoter for efficient enzyme expression.

The GH10 xylanase XYNIII is expressed in the hyper-cellulase-producing mutant PC-3-7, but not in the standard strain QM9414 of Trichoderma reesei. The GH11 xylanase gene xyn1 is induced by cellulosic and xylanosic carbon sources while xyn3 is induced only by cellulosic carbon sources in the PC-3-7 strain. In this study, we constructed a modified xyn3 promoter in which we replaced the cis-acting region of the xyn3 promoter by the cis-acting region of the xyn1 promoter.