Bacterial diversity in soil samples from two uranium waste piles as determined by rep-APD, RISA and 16S rDNA retrieval

Bacterial diversity in two uranium waste piles in Germany was studied. For this study, total DNA was recovered by two alternative procedures for direct lysis from a large number of soil samples drawn from different sites and depths of the piles. Significant differences in the bacterial composition of the samples investigated were revealed by the use of rep-APD, RISA, and 16S ARDREA. The 16S rDNA retrieval allowed also to demonstrate that both uranium wastes were dominated by Thiobacillus ferrooxidans and by several Pseudomonas species of g-subdivision of the Proteobacteria. Three kinds of T. ferrooxidans 16S and IGS rDNA specific fragments corresponding to the recently described three phylogenetic groups of this species (Flemming at al., 1999) were amplified in different ratios from distinct soil samples which were polluted with heavy metals to different extent. This microdiversity probably reflects the genetic adaptation of the uranium waste strains to the different heavy metal concentrations in their natural surrounding.