Transformation of Salmonella typhimurium with plasmid DNA: Differences between rough and smooth strains

Abstract

Lipopolysaccharide-defective mutants of Salmonella typhimurium were transformed by plasmid DNA with a Ca2+ treatment method. Only those mutants with an Rc or Rd2 chemotype, due to galE or rfaF mutations, respectively, gave efficiencies greater than 105 transformants per μg of DNA, frequencies 8- to 630-fold higher than with smooth strains or other rough mutants.