VERFAHREN ZUR HERSTELLUNG VON REKOMBINANTEN PLASMIDEN

The invention relates to a culture system for stable and high-level production of DNA contained on recombinant plasmids, and to the bacteria and plasmids which comprise the culture system. The bacterial cell chromosome is irreversibly altered, in one embodiment, so as to produce a substance toxic to the bacterium; in a second embodiment so as to render the cells unable to synthesize and assimilate an essential metabolite, and, in a third embodiment, to be incapable of producing a required intracellular protein that does not lead to a secreted product. In every case, the recombinant plasmid includes genetic material which functionally complements the chromosomal alteration. If the DNA on the plasmid is to be used in therapeutic applications or for administration to eukaryotes, the genetic material will have no functional or structural equivalent in eukaryotic cells, and will not result in production of mRNA or a polypeptide that acts on any eukaryotic cell component. Any peptide produced is, desirably, not toxic to the bacterial cells.