Bacterial diversity and monitoring of Geobacter sp. in uranium contaminated soils

Bacterial diversity was investigated by using the 16S rDNA retrieval in soil samples collected from a uranium mining waste pile called Haberland situated near the town of Johanngeorgenstadt, Germany, and from one uranium mill tailings in the USA, namely Shiprock, New Mexico. Significant differences were found in the composition of the bacterial communities at the studied sites. Alpha-Proteobacteria and representatives of the Holophaga/Acidobacterium phylum are predominant at the uranium mining waste pile Haberland, whereas the Shiprock uranium mill tailings is mainly occupied by Bacillales, g-Proteobacteria, and Green non-sulfur bacteria. The observed differences in the composition of the bacterial communities in the two studied environments are most probably connected to their different grade of contamination with heavy metals, and also to their different geographic and geologic origin (1).
Representatives of the Geobacter genus were found in both samples studied, but mainly by using Geobacter specific primers. This indicates that the Geobacter populations are probably not predominant in the studied environments. The exact quantification of these populations will be performed by using Real-Time PCR (work in progress). Geobacteracea are involved in reduction of heavy metals (e.g. iron) and radionuclides (e.g. uranium). Because these bacteria can significantly influence the mobility of the mentioned metals (2) their quantification in the uranium wastes is of great importance.

References:

1. Geißler, A. (2003) Molekulare Analyse der bakteriellen Diversität in Uranabraumhalden. Diploma Thesis,
Wissenschaftlich-Technische Berichte des Forschungszentrums Rossendorf FZR-377.

2. Lovley, D. R. et al. (1993) Archives of Microbiology 159: 336-344.