Transformation of the nematode-trapping fungus Arthrobotrys oligospora

The nematode-trapping fungus Arthrobotrys oligospora was transformed to hygromycin resistance using the hygromycin-B phosphotransferase gene from Escherichia coli under the control of various heterologous fungal promoters. Plasmid DNA was introduced into fungal protoplasts by polyethylene glycol/CaCl2 treatment. Transformation frequencies varied between 1-6 transformants per microgram DNA. Seven out of 13 integration events analyzed from transformants were single copy integrations, whereas the remaining were multiple and more complex integrations. The addition of restriction enzymes during transformations increased the frequency of single copy integrations. Co-transformation, using the E. coli uidA gene encoding the beta-glucuronidase reporter gene under the control of an Aspergillus nidulans promoter, occurred at frequencies of up to 63%.