Studies of Protoplast Fusion in Streptomyces chrysomallus

Abstract

Conditions for the regeneration of cells from protoplasts of S. chrysomallus, a producer of the peptide antibiotic actinomycin, are described. Regeneration of fusion products was most efficient at 27.degree.-30.degree. C on regeneration R2 medium containing 0.25 M sucrose. The addition of phosphate (150-300 mg l-1) to the medium and incubation at 23.degree. C were optimal for the regeneration of individual strains. Highest recombination frequencies after protoplast fusion were obtained by fusing protoplasts in the presence of 45% (wt/vol) 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.