Archaeal and bacterial populations in soil and water samples from the uranium mill tailings Gittersee/Coschütz

Bacterial and archaeal populations in soil and water samples of the uranium mill tailings Gittersee/Coschütz were studied by using the rDNA retrieval applying different sets of PCR amplification primers. Bacterial communities found in both soil and water samples had similar composition as estimated via analyses of the constructed 16S rDNA43F-1404R and 16S rDNA7F-1513R clone libraries. They consisted of proteobacteria (mainly from the gamma-subclass) and of representatives of the Cytophaga/Flavobacterium/Bacteroides (CFB) group. In the soil samples Gram-positive bacteria were found as well. These results are in contrast to those obtained by the analysis of the samples collected from the uranium mining waste pile near the town of Johanngeorgenstadt where members of the alpha proteobacteria and of the Holophaga/Acidobacterium phylum were found to be predominant by using the same 16S rDNA PCR amplification primers (1, 2, 3).
The analysis of the water samples applying the ribosomal intergenic spacer amplification rDNA retrieval using the 16S rDNA968F and 23S rDNA130R PCR primers revealed much higher diversity. In addition to the members of the Proteobacteria and of the CFB, populations of Nitrospira, Verrucomicrobia, Planctomycetales, Actinobacteria and also of several novel bacterial divisions were found (4). This result is due to the primer structures (5).
The identified archaeal populations, in contrast to those of the bacteria, were not very diverse in the studied environment. In the archaea-specific 16S rDNA21F-958R clone libraries constructed for the above mentioned soil and water samples only a few populations of not yet cultured Crenarchaeota were found (6).
Most of the 16S rDNA sequences obtained in this work showed no close phylogenetic affiliation to cultured bacteria or archaea. For this reason, it is difficult to predict the phenotypic properties and the ecological role of the corresponding organisms. However, it is interesting that the most related 16S rDNA sequences found in the Gene Bank were retrieved in environments with geologic and ecological properties similar to those of the uranium wastes, such as gold mine and other acid mine drainage systems (7, 8).
Efforts to culture representatives from some of the most predominant microbial populations are in progress.

References

1. Selenska-Pobell, S. et al. (2002) Bacterial communities in uranium mining waste piles and their interaction with heavy metals, p.455-464; In Uranium in the aquatic environment. Springer-Verlag.
2. Selenska-Pobell, S., et al. (2001) Antonie van Leeuwenhoek 79, 149-161.
3. Geißler, A. (2003) Molekulare Analyse der bakteriellen Diversität in Uranabraumhalden. Diploma Thesis, FZR-Report No. 377
4. Selenska-Pobell, S. (2002) Diversity and activity of bacteria in uranium waste piles, p. 225-253; In, Interactions of Microorganisms with Radionuclides. Elsevier Sciences, Oxford, UK.
5. Derakshani, M., et al. (2001) Appl. Environ. Microbiol. 67: 623-631.
6. Radeva, G. and Selenska-Pobell, S. (2003) FZR-Report No. 373, p. 29
7. Takai, K., et al. (2001) Appl. Env. Microbiol. 67, 5750-5760.
8. Stein, L., et al. (2002) FEMS Microb. Ecol. 42, 431-440.