Transformation of Thiobacillus versutus with plasmid DNA

The representative of the facultatively chemolithotrophic thiobacilli, Thiobacillus versutus has been successfully transformed for the first time with plasmid DNA. The plasmid used for the transformation study was pKK2, a derivative of the broad host range pSa plasmid conferring Km resistance being effectively expressed in T. versutus. Different methods inducing an artificial state of competence were tested. Transformants were obtained at the efficiency of about 10(3) per micrograms of DNA. pKK2 appeared to be compatible with T. versutus indigenous plasmids, but for stable maintenance it required constant selective pressure.