Cellulase hyperproducing mutants derived from the fungus Trichoderma reesei QM9414 produced large amounts of cellulase at the enzymatic and transcriptional levels.

Cellulase hyperproducing mutants derived from the fungus Trichoderma reesei QM9414 were analyzed. They exhibited higher filter-paper degrading activity and a lower growth rate than the wild-type QM9414 strain. Transcription of the cellobiohydrolase I and endoglucanase I genes in the mutants was also greater than that of QM9414, suggesting that cellulase hyperproduction by these mutants was regulated at the transcriptional level.