Rapid transformation of high cellulase-producing mutant strains of Trichoderma reesei by microprojectile bombardment

Intact conidia of three industrially relevant strains of Trichoderma reesei were effectively transformed by particle bombardment. Transformations were carried out individually with plasmids carrying either the fungal amdS or bacterial hph gene as a selectable marker and by cotransformation with both plasmids. Transformant yields with single plasmids were up to 11 stable tr ansformants per mu g DNA at the bombardment distance of 6 cm. Mitotic stabi lity of the transformants was 75-100% and the cotransformation efficiency a veraged 92% when the first selection was performed on hygromycin B plates. The entire procedure could be completed in 1 week with the hph marker.