Studies of Protoplast Fusion in Streptomyces chrysomallus

Institut für Biochemie und Molekulare Biologie, Technische Universität Berlin, Franklinstrasse 29, D-1000 Berlin 10, F.R.G. Abteilung Botanik, Technische Universität Berlin, Strasse des 17. Juni 135, D-1000 Berlin 12, F.R.G. ABSTRACT SUMMARY: Conditions for the regeneration of cells from protoplasts of Streptomyces chrysomallus, a producer of the peptide antibiotic actinomycin, are described. Regeneration of fusion products was most efficient at 27-30 °C on regeneration R2 medium (Okanishi et al ., 1974) containing 0.25 M-sucrose. The addition of phosphate (150-300 mg 1 -1 ) to the medium and incubation at 23 °C proved to be optimal for the regeneration of individual strains. Highest recombination frequencies after protoplast fusion were obtained by fusing protoplasts in the presence of 45% (w/v) polyethylene glycol 6000. With strains that produce no, or little antibiotic, protoplasts must be present in excess in fusion mixtures in order to overcome inhibition of regeneration by the antibiotic-producing partner.