Transformation of Aspergillus oryzae with a dominant selectable marker

Abstract Aspergillus oryzae strain U1638 has been transformed to phleomycin resistance using a phleomycin based vector. Protoplasts were generated using Novozyme 234 and regenerated on sucrose-stabilized minimal medium containing 200 μg ml −1 phleomycin. A frequency of 3 to 7 transformants per 10 6 viable protoplasts was obtained. All transformants tested showed increased resistance to phleomycin when subcultured onto selective medium and the mitotic stability of the transformants was 100% after growth without selective pressure. The vector sequences appeared to be integrated into the A. oryzae U1638 genome at multiple sites.