Trichoderma reesei strains for production of cellulases for the textile industry

Trichoderma reesei is a biotechnically important filamentous fungus used commercially in enzyme production. T. reesei is also one of the best known cellulolytic organisms, producing readily and in large quantities a complete set of extracellular cellulases for the degradation of crystalline cellulose. In addition to T. reesei, a wide variety of other bacteria and fungi also produce cellulolytic enzymes. Cellulases originating from various organisms and having different characteristics are used industrially in many applications, such as in the textile industry in finishing of denim fabric to impart a stonewashed appearance (biostoning) and in biofinishing of cotton. In this work T. reesei strains producing significant amounts of homologous and heterologous cellulases and having defined cellulase profiles were constructed for specific industrial applications, i.e. biostoning and biofinishing of cotton. The production of T. reesei endoglucanase II (EGII), cellobiohydrolases I and II (CBHI and CBHII) was improved in separate strains. Strains producing high amounts of EGI and EGII without CBHs or CBHI and CBHII without the main EGs were also constructed. The cellulase genes were expressed under the powerful T. reesei cbh1 promoter; in a transformant overproducing both CBHI and CBHII, the cbh2 promoter was also used for cbh2 expression. The level of endoglucanase activity produced by the EGII-overproducing transformants correlated with the copy number of the egl2 expression cassette. Production of the major secreted cellulase CBHI was increased up to 1.5-fold and production of CBHII fourfold compared with the parent strain. In transformants overproducing both CBHI and CBHII, production of CBHI was increased up to 1.6-fold and production of CBHII up to 3.4-fold as compared with the host strain and approximately similar amounts of CBHII protein were produced by using the cbh1 or cbh2 promoters.