Construction of cellulase hyperproducing strains derived from polyploids of Trichoderma reesei

The mycelial mat of Trichoderma reesei strain OM 6a was treated with 0.1% ( w/v) colchicine solution for 14 days and designated M14. The cellulase prod uctivity of strain M14 was not much higher than that of the original strain . When conidia of M14 were treated with ethylmethane sulphonate (EMS) solut ion, the cellulase hyperproducers, M14-1 and M14-2, were isolated using a s election medium containing Avicel. The DNA content of M14-1 and M14-2 was h igher than that of the original strain. Cellulase productivity per mycelium of these strains increased and was higher than that of the original strain . The cellulase productivity did not change through ten generations when th ese strains were cultivated successively on a medium containing Avicel. It was concluded that cellulase hyperproducers, whose cellulase productivity p er mycelium increased, could be obtained when the conidia of strain M14 wer e treated with EMS.