P. Sancheztorres et al., DEVELOPMENT OF A TRANSFORMATION SYSTEM FOR TRICHODERMA-LONGIBRACHIATUM AND ITS USE FOR CONSTRUCTING MULTICOPY TRANSFORMANTS FOR THE EGL1 GENE, Applied microbiology and biotechnology, 41(4), 1994, pp. 440-446
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
.