Interactions of microorganisms with U(VI).

The release of uranium into the environment is a subject of great public concern due to the chemical and radiological toxicity of this radionuclide. For the development of effective remediation strategies and reliable risk assessment, consolidated knowledge about the uranium behavior in contaminated sites is necessary. Beside the interactions with inorganic soil components, an important role in the migration behavior of uranium play the naturally occurring microorganisms. A high number of studies were dedicated to elucidate the bacterial processes responsible for the binding of uranium. However, little is known about the processes implicated in the complexation of this radionuclide by representatives of the second microbial domain of life, the “Archaea”. The objective of the present work was to investigate whether the structural differences between the cell surfaces of representatives of archaea and bacteria influence the cellular localization and the molecular environment of U(VI) bound by the two kinds of organisms. For this, Transmission Electron Microscopy (TEM), Time-Resolved Laser-induced Fluorescence Spectroscopy (TRLFS), and X-ray Absorption Spectroscopy (XAS) were used.