Associations of trivalent actinides with microorganisms; Characterization of their coordination environment by time-resolved laser-induced fluorescence spectroscopy (TRLFS)

Ozaki, Takuo; Kimura, Takaumi ; Onuki, Toshihiko; Francis, A. J.*

Elucidation of the coordination structure of radionuclides on microbial cells is necessary to precisely predict the effect of microorganisms on the environmental behavior of radionuclides. In this study, the association of f-elements, Eu(III) and Cm(III) with 13 kinds of microorganisms was examined by a batch method and time-resolved laser-induced fluorescence spectroscopy (TRLFS). All the microorganisms used showed rapid kinetics and high distribution ratios of Eu(III) and Cm(III) on the cell surfaces. However, characteristics of the coordination environment of Eu(III) on the microorganisms significantly differed to each other: halophiles (4 strains) provided stronger ligand fields for Eu(III) compared to those non-halophiles (9 strains) did. These findings suggest that trivalent f-elements on the cells of halophiles are retained more tightly than those on non-halophiles.