Molecular characterization of Acidithiobacillus ferrooxidans and A-thiooxidans strains isolated from mine wastes in Brazil

Nineteen strains of Acidithiobacillus ferrooxidans and Acidithiobacillus th iooxidans, including 12 strains isolated from coal, copper, gold and uraniu m mines in Brazil, strains isolated from similar sources in other countries and the type strains of the two species were characterized together with t he type strain of A. caldus by using a combination of molecular systematic methods, namely ribotyping, BOX- and ERIC-PCR and DNA-DNA hybridization ass ays. Data derived from the molecular fingerprinting analyses showed that th e tested strains encompassed a high degree of genetic variability. Two of t he Brazilian A. ferrooxidans organisms (strains SSP and PCE) isolated from acid coal mine waste and uranium mine effluent, respectively, and A. thioox idans strain DAMS, isolated from uranium mine effluent, were the most genet ically divergent organisms. The DNA-DNA hybridization data did not support the allocation of Acidithiobacillus strain SSP to the A. ferrooxidans genom ic species, as it shared only just over 40% DNA relatedness with the type s train of the species. Acidithiobacillus strain SSP was not clearly related to A. ferrooxidans in the 16S rDNA tree.