Actinomycin Biosynthesis by Protoplasts Derived from Streptomyces parvulus

Conditions are described for the formation of protoplasts from Streptomyces parvulus that are able to synthesize actinomycin D de novo. Antibiotic synthesis by protoplasts, in contrast to that by mycelium, was sensitive to inhibition by actinomycin D and to a decrease in sucrose concentration. On the other hand, synthesis by mycelium was much more sensitive to inhibition by amino acid analogs (d-valine, cis-3-methylproline, and alpha-methyl-dl-tryptophan). In addition, the uptake of amino acids (l-methionine, sarcosine, and l- and d-valine) by protoplasts was significantly lower than that by mycelium. The advantages and limitations of using protoplasts for studying in vivo actinomycin synthesis are discussed.