Microbial diversity in ground water at the deep-well monitoring site SI5 of the radioactive waste depository Tomske-7, Siberia, Russia

Microbial diversity was studied in ground waters collected from a monitoring well at the radioactive waste depository Tomsk-7, Siberia, Russia, applying the 16S rDNA retrieval. The results demonstrated dominance of Betaproteobacteria, Bacteroidetes, and a novel “Cyanobacteria-like” group. The archaeal populations are represented by methanogens and three distinct clusters of Crenarchaeota. The autotrophic bacterial diversity was estimated via the RubisCO approach and the results confirm the dominance of Betaproteobacteria. Oligotrophic bacteria, from the groups of Alphaproteobacteria and Actinobacteria were isolated from the studied site. The strains tolerate relatively high concentration of different heavy metals and interact effectively with uranium. EXAFS analysis demonstrated that they immobilize U(VI) at pH 4.5 extracellularly in a form of meta-autunite. At pH 2 the U was bound by the organic phosphate residues of the cells. The environment around the radioactive waste repository site Tomsk-7 possesses microorganisms with a potential to bind and transport radionuclides.