Plasmid DNA in acidophilic, chemolithotrophic thiobacilli

Plasmid patterns were determined in 15 strains of iron-oxidizing Thiobacillus ferrooxidans. In four of these strains plasmid DNA was not detected. In the other strains the molecular weights of plasmids ranged from 5 x 10(6) to 50 x 10(6) and each strain had a different plasmid composition. The change of growth substrate from ferrous iron to tetrathionate did not affect the plasmid pattern in T. ferrooxidans nor did it in T. acidophilus, which was adapted from glucose to grow on tetrathionate.