Direct transfer of plasmid DNA between Streptomyces spp. and E. coli by electroduction

We describe a simple and reliable method which allows the direct transfer of shuttle plasmids between Streptomyces spp. and E. coli. The method is based on the fact that plasmid DNA molecules can be released or taken up from cells under conditions of electroporation. When a suspension of a plasmid-containing Streptomyces spp. is mixed with electroporation-competent E. coli and submitted to an electric pulse, plasmid DNA transfer to the E. coli recipient takes place. Two different Streptomyces spp. (S. lividans TK23, or TK24 and S. rimosus 554w) were effective donors, and the method was successfully employed to transfer four different bifunctional vectors (pPM801, pFD666, pRL270X and pZG5) varying in size from 5.2-14.4 kb, to E. coli. This provides a convenient method for the analysis of Streptomycete transformants.