Physiological and Genetic Characterization of Thiobacillus Ferrooxidans Strains Used in Biohydrometallurgy

Abstract By using pulsed-field gel electrophoresis, hereditary polymorphism of the chromosomal DNA structure was shown in Thiobacillus ferrooxidans strains isolated from natural and biomining environments and cultivated on different inorganic substrates. Each strain was found to be characterized by a unique restriction pattern of chromosomal DNA reflecting changes in its nucleotide sequence arising in the process of adaptation to specific environmental conditions. Some strains exhibited nonhereditary alterations in chromosomal DNA developing in response to switching to a different oxidation substrate or in the course of adaptation to high concentrations of metal ions. Increased metal resistance of such strains was found to correlate with the number of copies of resistance genes. Amplification of DNA fragments hosting resistance genes disappeared in repeated transfers of strains on the medium lacking the given inducer. With other strains, however, no structural alterations in the chromosomal DNA were detec...