Journal of Biotechnology, 19 (1991) 117-122 0 1991 Elsevier Science Publishers B.V. 0168-1656/91/$03.50 ADONIS 0168165691000991 BIOTEC 00614 Short Communication Transformation of Aspergillw oryzae with a dominant selectable marker S. Cheevadhanarak ‘* *, G. Saunders ‘, D.V. Renno I, T.W. Flegel 2 and G. Holt t ’ School of Biological and Health Sciences, The Polytechnic of Central London, London, U.K. and ’ Department of Biotechnology Faculty of Science, Mahidol University. Bangkok, Thailand (Received 12 October 1990; revision accepted 5 December 1990) 117 Summary Aspergillus orytae 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 pg ml-’ phleomycin. A frequency of 3 to 7 transformants per lo6 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. ovzae U1638 genome at multiple sites. Aspergillus oryzae; Phleomycin resistance; Transformation Introduction Aspergillus otyzae is a filamentous fungus which is of industrial importance in oriental countries for bioprocessed food such as sake, soy sauce and miso. It is also Correspondence lo: G. Saunders, The Polytechnic of Central London, 115 New Cavendish Street, London WlM SJS, U.K. * Present address: Dept. of Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400. Thailand.