Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

Uranium pollution of soils and waters within the environment is from big concern. A range of remediation strategies were developed using chemicals and industrial equipment. As a consequence, the conventional remediation of polluted sites is elaborated and time-consuming. Microorganisms can affect the solubility of uranium and thus they could be an appropriate alternative in bioremediation approaches. It is well described that microorganisms could interact with metals in different ways. One of these is called biomineralization, and is defined as an interaction mechanism between microorganisms and metals whereby biological produced minerals capture pollutants within stable solid phases.
We investigated natural occurring fungi which were directly isolated from the flooding water of the former uranium mine Königstein in Germany. The isolated strain KS1 Penicillium simplicissimum displayed the ability to immobilize high amounts of uranium from surrounding solutions. Metabolism-dependent uranium removal experiments revealed in different interaction mechanisms of KS1 with uranium(VI). By transmission electron microscopy (TEM) we observed that the immobilization of the soluble uranium(VI) took place by bioaccumulation within the cells and furthermore by biomineralization outside of the cells. EDX investigations resulted in amorphous phosphate-minerals inside and outside the cells. In addition, enzymatic analysis displayed organic acids which were produced by the fungi and released to the solution. The results of our investigations revealed that the isolated fungi KS1 could be a suitable candidate for further bioremediation studies. Uranium was immobilized effectively, fast and possibly within stable solid phases. Compared to conventional remediation approaches the use of microorganisms should be taken into account.