PhD thesis

Investigations on the microbiology of former underground uranium mines

PhD student:
Corinna Gagell
Dr. T. Arnold (HZDR), Prof. I. Röske (TU Dresden)

Toxic metals such as uranium can partially occur in elevated concentrations in the environment causing a health risk for humans. For this reason, since 1990 contaminated soils and waste water left from former uranium mine operations are cleaned in a time-consuming and expensive way in Germany. There are general two possible strategies remediating contaminated areas: i) the increase of contaminant solubility to achieve an increased metal mobility for later extraction and ii) the metal immobilisation through sequestration, complexation or changes in speciation. Besides abiotic factors microorganisms can have a great impact on metal solubility. For example, it was shown that the stimulation of microbial activity leads to reduction of U(VI) to U(IV) and thus to immobilisation. The usage of microorganisms as cost-effective and ecologically friendly alternative to classical methods of remediation is currently under discussion. However, the understanding of the interaction of toxic metals with microorganisms is still incomplete. Thus, this PhD work should contribute to a better understanding of this interaction.

Firstly, the microbial community of mine water from different former uranium mines should characterised by molecular techniques. The aquatic samples will be investigated with regard to microbial diversity and different chemical parameters. For the determination of microbial diversity 16S rDNA clone libraries will be created which will be analysed by sequencing. The quantity of microbial groups will be determined by CARD-FISH analysis. The metabolic activity of indigeneous microorganisms should be determined by 16S rRNA, DNA-SIP and MAR-FISH, respectively.

Lovley, D.R. (1991), Nature 350, 413-16