EN
One of many strategies of bacteria survival in a contaminated environment is plasmid-encoded resistance to toxic substances. D. desulfuricans wild strains isolated from soil and mud samples taken from contaminated sites were studied to identify plasmids in these bacteria and to examine their restriction profiles. The presence of plasmid DNA in all tested strains was demonstrated. Using B.stEII-digested DNA of phage λ. as the molecular standard, plasmid size was established at ~2.3 kbp. The restriction fragments obtained after cutting plasmid DNA with endonuclease HaeIII or AluI were better separated on gradient polyacrylamide gel than on homogeneous gel. Very high similarity between the fragment profiles was demonstrated, despite the different origins of the strains tested.