DEVELOPMENT OF A TRANSFORMATION SYSTEM FOR TRICHODERMA-LONGIBRACHIATUM AND ITS USE FOR CONSTRUCTING MULTICOPY TRANSFORMANTS FOR THE EGL1 GENE

An efficient transformation system for the fungus Trichoderma longibra chiatum has been developed. Transformation was obtained both by electr oporation and polyethyleneglycol treatment, using a plasmid carrying t he Escherichia coli hygromycin B phosphotransferase gene as a dominant selectable marker. The transformation frequency was 0.5 to 5 transfor mants /mu g plasmid DNA. Transformation normally occurred by tandem in tegration of the transforming DNA. A high percentage of the transforma nts were mitotically unstable. The efficiency of co-transformation was very high (around 90%), and several co-transformants containing multi ple copies of the egl1 gene encoding a P(1,4)-endoglucanase were obtai ned. Some of them secrete increased levels of endoglucanase to the cul ture medium. In addition, the E. coli lacZ gene was expressed in an ac tive form under control of the Aspergillus nidulans gpdA gene promoter .