The invention relates to methods for obtaining improved strains of filamentous ascomycete fungus, such as Trichoderma reesei, and the product of said method. The method includes contacting ascomycete cells comprising a reporter gene construct with a mutagen, wherein said reporter gene construct comprises a promoter operably linked with a reporter gene; culturing said ascomycete cells under conditions that repress activity of the promoter; and isolating said ascomycete cells that produce the reporter in amounts detectably higher than ascomycete cells which have not been contacted with the mutagen.
1. GOVERNMENT SUPPORT
 Portions of this work were funded by Subcontract No. ZCO-30017-01 with the National Renewable Energy Laboratory under Prime Contract No. DE-AC36-99GO10337 with the U.S. Department of Energy. Accordingly, the United States Government may have certain rights in this invention.