The U(VI) Speciation Influenced by Novel Bacterial Isolates from Mont Terri Opalinus Clay

High-level nuclear waste is supposed to be stored in deep geological formations. An example is the Opalinus clay formation located in the North-Western part of Switzerland (Mont Terri, Canton Jura) which is currently studied in terms of its suitability as host rock for future nuclear waste storage. Bacteria are ubiquitous in nature and together with archaea represent the only form of life which can inhabit and even thrive in the hostile environment of a nuclear waste repository. It is well known that bacteria can affect the actinide speciation through versatile mechanisms and therefore the migration behaviour. The presented work is embedded in the project “Microbial Diversity in Claystone (Opalinus Clay) and Interaction of Dominant Microbial Strains with Actinides” funded by the Federal Ministry of Economics and Technology (BMWi). The project is integrated in the German-Swiss cooperation within the Mont Terri Project.
The talk deals with the U(VI) interactions of two bacterial strains isolated from Mont Terri Opalinus clay, namely Paenibacillus sp. and Sporomusa sp.. The morphology/ surfaces functional groups of the strains have been characterized using microbiological techniques combined with potentiometry. Further, potentiometry and TRLFS results about the U(VI) species formed at the bacterial cell surfaces are presented. Emphasize of this work was to characterize the formed U(VI) species thermodynamically.