Plasmid profiles of Acidithiobacillus ferrooxidans strains adapted to different oxidation substrates

Plasmid profiles were studied in five Acidithiobacillus ferrooxidans strains of various origin cultivated on a medium with Fe2+, as well as adapted to such oxidation substrates as S0, FeS2, and sulfide concentrate. The method used revealed plasmids in all A. ferrooxidans strains grown on a medium with Fe2+. One plasmid was found in strain TFL-2; two plasmids, in strains TFO, TFBk, and TFV-1; and three plasmids were detected in strain TFN-d. The adaptation of strain TFN-d to sulfide concentrate and the adaptation of strain TFV-1 to S0, FeS2, or sulfide concentrate resulted in a change in the number of plasmids occurring in cells. In cells of strain TFN-d adapted to sulfide concentrate, the number of plasmids decreased from three to two. The number of plasmids in cells of strain TFV-1 adapted to different substrates varied from three to six depending on the energy source present in the medium: three plasmids were found after growth on FeS2, four after growth on S0, and six after growth on sulfide concentrate. The possible role of plasmids in the adaptation of A. ferrooxidans to new energy substrates and in the regulation of the intensity of their oxidation is discussed.