Involvement of plasmids in Streptomyces incarnatus phenotype.

The sinefungin producing, pock forming strain Streptomyces incarnatus was shown to be thiostrepton resistant. However, it does not produce thiostrepton and structurally related antibiotics. In this strain, five low copy plasmids of variable sizes were detected with electron microscopy. The strain S. lividans TK24 became thiostrepton resistant upon transformation by one of the plasmids of S. incarnatus.