Mechanistic understanding for biochemical and biological processes of uranium(VI) by time-resolved laser-induced fluorescence spectroscopy (TRLFS)


Mechanistic understanding for biochemical and biological processes of uranium(VI) by time-resolved laser-induced fluorescence spectroscopy (TRLFS)

Steudtner, R.; Hilpmann, S.; Bader, M.; Jessat, J.; Sachs, S.; Cherkouk, A.

The transfer of radionuclides into the food chain is of central concern for the safety assessment of both nuclear waste repositories and radioactive contaminated areas, such as legacies of the former uranium mining. The interaction of radionuclides, here in this particular case uranium(VI), with microorganism or plants is mostly described by transfer factors without knowing the underlying processes. In two examples we want present that luminescence spectroscopy is a powerful tool to study these unknowing processes of uranium(VI) on a molecular level.
Rock salt formations are considered as potential host rocks for the long-term storage of highly radioactive waste in a deep geological repository. Extremely halophilic archaea, e.g. Halobacterium species, dominate this habitat. We studied and compared the interactions of different extremely halophilic Halobacterium species with uranium(VI) by classical chemical and biological, by multi-spectroscopic and microscopic and by molecular biological methods. Depending on the used initial uranium(VI) concentration the different Halobacterium species showed a different bioassociation behaviour of uranium(VI). By using TRLFS the formation of uranium(VI) phosphate minerals, such as meta-autunite, as well as the complexation with carboxylate groups was observed as a function of the uranium(VI) concentration and the Halobacterium species.
In a second example, we studied the interaction of uranium(VI) with canola cells (Brassica napus) focusing on the concentration dependent impact of uranium(VI) on the cell metabolism. Previous studies showed, for instance, a speciation dependent influence of radionuclide uptake and translocation in plants [1]. Heavy metal stress induces the synthesis of metal-binding metabolites, storage of metal chelates in vacuoles or the secretion into the rhizosphere [2], which changes the plant cell metabolism. To study the interaction of lanthanides with Brassica napus on a cellular level, callus and suspension cells were exposed to uranium(VI). Besides the kinetics of the bio-association, the amount of associated uranium(VI) and its effect on cell growth and viability was determined. TRLFS was used as direct speciation technique to determine the uranium(VI) species on callus cells and the supernatant. In combination with high performance liquid chromatography (HPLC) experiments the metabolic answer of the callus cells during the presence of uranium(VI) will be investigated.

  • Lecture (Conference)
    4th International Workshop on Advanced Techniques in Actinide Spectroscopy (ATAS), 06.-09.11.2018, Nice, France

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Publ.-Id: 28730