Microbial mechanisms of radionuclide resistance

• Main Author: Dekker, L.
• Published: University College London (University of London) 2013
• Subjects: 570
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.626421

Widespread contamination of the environment with toxic heavy metals and radionuclides has resulted from industrial activities. This contamination is of considerable concern for the environment and human health. Some bacteria can tolerate high levels of these contaminants and may be useful in a bioremediation approach to remove or detoxify the contaminants. In order for such an approach to be undertaken, knowledge of the resistance mechanism(s) employed by the bacterium is required. Cobalt (Co) and cesium (Cs) radionuclides are produced in the generation of nuclear power. Bacteria resistant to Co and Cs were isolated from a nuclear fuel storage pond. The isolates were identified and their levels of resistance to non radioactive forms of Co and Cs were determined. The isolates were either resistant to Co or Cs, but did not show dual resistance. The isolates could be useful in the remediation of nuclear fuel storage ponds and other applications. Acidithiobacillus ferrooxidans is an acidophilic bacterium that thrives in metal contaminated environments and can withstand high levels of uranium (U). It is known that A. ferrooxidans is capable of biosorption of U(VI). To obtain a more complete picture of the processes and protein components involved in U(VI) resistance, the proteome of A. ferrooxidans grown in the presence and absence of U(VI) was analysed by combining two dimensional polyacrylamide gel electrophoresis with mass spectrometry-based protein identification. Most proteins that had increased expression were part of the general stress response or were involved in reactive oxygen species detoxification. The transcriptional regulation of selected genes of interest from the proteomics study, were additionally analysed by qPCR analysis. Surprisingly, there was no correlation between the proteomics and qPCR results. Targeted gene knockouts of genes potentially involved in U(VI) resistance were unsuccessful.