Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

Microorganisms have a potential to affect the mobility and overall environmental behaviour of uranium through solubility and speciation changes, biosorption, bioaccumulation or other transformations. Recently, three eco-types of A. ferrooxidans were recovered from different sites and depths of two uranium mining waste piles. These natural A. ferrooxidans isolates interact with uranium and tolerate this radionuclide in a type-specific way. In this study, we used a combination of Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy, Infrared Spectroscopy (IRS), Time-resolved Laser-Induced Fluorescence Spectroscopy (TRLFS), Transmission Electron Microscopy (TEM) and Energy-Dispersive X-ray (EDX) analysis to conduct atomic and molecular scale studies on U(VI) interaction with the three eco-types of A. ferrooxidans. On the basis of the combined information from the above mentioned methods we conclude that the uranium is bound by A. ferrooxidans cells mainly in a form of organic uranyl phosphate complexes. Moreover, the largest part of the uranium accumulated by A. ferrooxidans cells is located within the extracellular polysaccharides. Additionally, some part of the uranium was found on the cell walls. A limited amount of the metal enters the cells and is than detoxified through sequestration by intracellular polyphosphate bodies.