Interactions of the Mont Terri Opalinus Clay Isolate Sporomusa sp. MT-2.99 with Curium(III) and Europium(III)

Abstract

Bacterial cell walls have great potential to influence the speciation and mobility of actinides and lanthanides in the environment. In this study we explored the unknown interaction between Cm(III)/Eu(III) and cell-suspensions of Sporomusa sp. MT-2.99, a novel isolate recovered from Opalinus Clay (Mont Terri, Switzerland). The Cm(III)/Eu(III) binding by the cell surface functional groups was studied by potentiometry combined with time-resolved laser-induced fluorescence spectroscopy (TRLFS). This article provides stability constants of Cm(III)/Eu(III) complexed by cell surface functional groups. We could show that as a function of pH Cm(III)/Eu(III) binding occurred to hydrogen phosphoryl, carboxyl and deprotonated phosphoryl sites. Both metals showed a similar interaction process consisting of surface complexation (major) with high thermodynamic stability and an irreversible binding within the cell envelope (minor).

Keywords:

• bacteria
• complexation
• curium
• europium
• Sporomusa sp.
• TRLFS
• potentiometry

Acknowledgments

The authors are indebted to the U.S. Department of Energy, Office of Basic Energy Sciences, for the use of ²⁴⁸Cm via the transplutonium element production facilities at Oak Ridge National Laboratory; ²⁴⁸Cm was made available as part of collaboration between HZDR and the Lawrence Berkeley National Laboratory (LBNL). The authors thank the BGR for providing the clay samples.

Additional information

Funding

This work was funded by BMWi under contract numbers 02E10618 and 02E10971.