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

The bacterial diversity in two uranium waste piles was studied. Total DNA w as recovered from a large number of soil samples collected from different s ites and depths in the piles using two procedures for direct lysis. Signifi cant differences in the bacterial composition of the samples were revealed by the use of rep-APD, RISA and 16S ARDREA. The 16S rDNA analyses showed th at the uranium wastes were dominated by Acidithiobacillus ferrooxidans and by several Pseudomonas species classified in the gamma -subdivision of the Proteobacteria. The three kinds of A. ferrooxidans 16S and IGS rDNA specifi c fragments that were found corresponded to the three phylogenetic groups r ecognised in this species. This microdiversity probably reflects the geneti c adaptation of the uranium waste strains to different concentrations of he avy metals.