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Cellulase hyperproducers of Trichoderma reesei can be constructed using autopolyploidization and haploidization techniques. To increase the efficiency of this method, the active nuclear shuffling system in a swollen conidium was effective. A dried mature green conidium of a model strain, T. reesei QM6a (IFO 31326), was swollen to make room for a larger autopolyploid nucleus. After colchicine treatment, a larger autopolyploid nucleus was produced in such a swollen conidium. Benomyl treatment of swollen conidia generated multiple smaller nuclei from one larger autopolyploid nucleus. Those smaller nuclei were transported through conidia to mycelia after germination. This system could contribute to increasing the efficiency of genetic shuffling.

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The multinucleate conidia were produced from the green mature conidia of Trichoderma reesei Rut C-30 strain by colchicine treatment. The strain with higher Filter paper degrading ability was selected among those conidia using a double layer selection medium. The selected strain, JS-2 was able to collapse the filter paper within 15 min but the original strain took 25 min to collapse it completely. Moreover, the amount of reducing sugar in the L-type glass tube of the strain, JS-2 was greater than that of the original strain. The Avicel, CMC-Na, and Salicin hydrolyzing activity of the strain, JS-2, increased 2.1 times, 1.2 times, and 3.6 times higher than that of the original strain.

The cellulolytic fungus, Trichoderma has oval and mononucleate conidia. When these conidia are incubated in a liquid medium, they begin to swell and their shape becomes spherical followed by an increase in inner space. In such swollen conidia, it is possible to produce a larger autopolyploid nucleus using a mitotic arrester compared with the case of the original conidia. In this study, polykaryon formation was attempted using these swollen conidia. Dried mature green conidia of Trichoderma reesei QM6a (IFO 31326) were incubated in Mandel's medium in order to swell. The swollen conidia were treated with a mitotic arrester, colchicine, for autopolyploidization. After autopolyploidization, polykaryon formation was carried out using the swollen conidia. After the treatment, multiple smaller nuclei whose diameter was almost the same as that of the original strain were generated from an autopolyploid nucleus in a swollen conidium. A cellulase hyperproducer without decrease in growth rate could be selected using such swollen conidia.