Malachite green treatment of industrial Penicillium chrysogenum protoplasts results in increased penicillin-V formation

We attempted protoplast fusion in order to generate gene transfer between an industrial strain of Penicillium chrysogenum and a fission yeast, Schizosaccharomyces pombe. The Penicillium strain was treated with malachite green. The S. pombe strain was auxotrophic for lysine. The regenerated colonies showed Penicillium morphology. The number of Penicillium colonies was significantly higher when the inactivated Penicillium protoplasts were fused to S. pombe protoplasts than in the self-fusion control experiments. We randomly isolated colonies from the regeneration plates and measured beta-lactam formation in cultures from shaken flasks. Antibiotic production was increased in colonies originated from the malachite green-treated protoplasts. Received 2 June 1998/ Accepted in revised form 30 November 1998