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number of the egl2 expression cassette. One copy of the egl2 expression cassette in which the egl2 was under the cbh1 promoter increased production of endoglucanase activity 2.3-fold, and two copies increased production about 3-fold above that of the parent strain. When the enzyme with elevated EGII content was used, an improved stonewashing effect on denim fabric was achieved. A T. reesei strain producing high amounts of EGI and -II activities without CBHI and -II was constructed by replacing the cbh2 locus with the coding region of the egl2 gene in the EGI-overproducing CBHI-negative strain. Production of endoglucanase activity by the EG-transformant strain was increased fourfold above that of the host strain. The filter paper-degrading activity of the endoglucanase-overproducing strain was lowered to below detection, presumably because of the lack of cellobiohydrolases.The filamentous fungus Trichoderma reesei is known as an efficient producer of cellulases. The cellulolytic system of T. reesei is composed of two cellobiohydrolases (CBHI and CBHII) and at least five endoglucanases (EGI, EGII, EGIII, EGIV, and EGV) (19,20). Lack of EGII (originally called EGIII [18]) production reduces the endoglucanase activity in the culture supernatant by as much as 55%, whereas lack of EGI reduces it by only 25% (21). Thus, EGII is proposed to account for most of the endoglucanase activity produced by T. reesei (21). T. reesei EGI represents 5 to 10% of the secreted protein (16). The production of EGI has been improved in T. reesei by placing the egl1 gene under the control of the strong promoter of the Trichoderma CBHI (cbh1) gene and by increasing the copy number of the egl1 gene (8).Cellulases are used widely in the textile industry in treatments of cellulose-containing textile materials during their manufacture and finishing (5). The most well-known application is the use of cellulases in biostoning. Biostoning of fabric means the use of cellulases in place of, or in addition to, the use of pumice stones for the treatment of denim fabric to impart a stonewashed effect. Heikinheimo et al. (7) showed that T. reesei-purified cellulase EGII was the most effective at removing color from denim, producing a good stonewashing effect with the lowest hydrolysis level. Endoglucanases are important also for degradation of ␤-glucan in feed. Degradation of ␤-glucan lowers the viscosity of the intestinal contents and this improves the quality of the feed (3).In this study we have constructed T. reesei strains that produce elevated amounts of endoglucanase activity. The aim of our work was to construct different tailored high endoglucanase activity-producing strains for specific applications. We have improved the production of the EGII enzyme in T. reesei and we have constructed a T. reesei strain that produces high amounts of EGI and -II without any cellobiohydrolases. Cellulase preparations derived from these T. reesei overproduction strains were tested on the biostoning application. MATERIALS AND METHODSMicrobial strains and plasmi...

Cellulases are widely used to age denim fabrics. In this work the effects of three purified monocomponent cellulases, EG I, EG II, and CBH I, and two different cellulase mixtures produced by genetically modified strains of Trichoderma reesei are compared for stone washing denim fabrics. Stone washing effects are evaluated by analyzing the soluble reducing sugars, absorbance, and lightness values of the treatment solutions. The prop erties of denim swatches are evaluated by reflectance units and by a panel. Purified cellulase EG II is most effective at removing color from denim, producing a good stone washing effect with the lowest hydrolysis level. Treatment with CBH I does not produce any stone washing effect, even at high enzyme dosages. The commercial cellulase Ecostone® L produces a good stone washing effect, but the experimental cellulase mixture Cellulase B removes color only with the highest enzyme dosage, i.e., when the amount of EGS in the mixture is high enough.

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