HR: 0830h
AN: B41D-0918    [PDF]
TI: Association of Eu(III) and Cm(III) With Halophiles
AU: * Ozaki, T
EM: tozaki@popsvr.tokai.jaeri.go.jp
AF: Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195, Japan, Tokai, 319-1195 Japan
AU: Takenaka, Y
EM: yokot@popx.tokai.jaeri.go.jp
AF: Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195, Japan, Tokai, 319-1195 Japan
AU: Ohnuki, T
EM: ohnuki@sparclt.tokai.jaeri.go.jp
AF: Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195, Japan, Tokai, 319-1195 Japan
AU: Gillow, J B
EM: gillow@bnl.gov
AF: Environmental Sciences Department, Brookhaven Natinoal Laboratory, Upton, New York 11973, USA, Upton, NY 11973 United States
AU: Francis, A J
EM: ajfrancis@bnl.gov
AF: Environmental Sciences Department, Brookhaven Natinoal Laboratory, Upton, New York 11973, USA, Upton, NY 11973 United States
AB: Halophiles live in high ionic strength brine. The mechanisms of metal association with these microorganisms are poorly understood. In this study, we determined the distribution of Eu(III) and Cm(III) on halophiles, {\it Halomonas} sp. (WIPP1A) which was isolated from the Waste Isolation Pilot Plant (WIPP) repository in Carlsbad, US., {\it Halomonas elongata} (ATCC33173), {\it Halobacterium salinarum} (ATCC19700), and {\it Halobacterium halobium} (ATCC43214) and examined the coordination environment of Eu(III) adsorbed on the cells by time-resolved laser-induced fluorescence spectroscopy (TRLFS). The cells of {\it Halomonas} sp. and {\it H. elongata} were grown in media containing 10 - 15 w/v% and 3.5 - 30 w/v% NaCl, respectively. {\it Halobacterium salinarum} and {\it H. halobium} were grown in media containing 25 w/v% NaCl. The logarithmic distribution coefficient (log K$_{d}$) was measured by using the cells at the late exponential phase. After washing the cells with the same concentrations of NaCl, the cells were mixed with 1$\times$10$^{-6}$ mol dm$^{-3}$ Eu(III) and 1$\times$10$^{-8}$ mol dm$^{-3}$ Cm(III) at pH 5 in the same concentrations of NaCl and log K$_{d}$ of Eu(III) and Cm(III) was determined. For {\it Halomonas} sp. and {\it H. elongata}, log K$_{d}$ was determined as a function of NaCl concentrations. The coordination environment of Eu(III) adsorbed on the cells was estimated by TRLFS. For TRLFS measurements, samples were prepared by adding cells to a solution of 1$\times$10$^{-3}$ mol dm$^{-3}$ Eu(III) with the same concentrations of NaCl as the culture media. For {\it Halomonas} sp. and {\it H. elongata}, log K$_{d}$ of Cm(III) was apparently larger than that of Eu(III) at all the NaCl concentrations examined. On the other hand, log K$_{d}$ of Eu(III) and Cm(III) for {\it H. salinarum} and {\it H. halobium} was almost identical. Our previous study demonstrated that non-halophiles, {\it Chlorella vulgaris}, {\it Bacillus subtilis}, and {\it Pseudomonas fluorescens} show no preferences between these elements. Chemical properties of Eu(III) and Cm(III) are almost identical. Our findings suggest that the difference in log K$_{d}$ of Eu(III) and Cm(III) for {\it Halomonas} sp. and {\it H. elongata} is reflected due to the slight difference in the affinity of Eu(III) and Cm(III) for the functional groups on the cell surface commonly present in the microorganisms of the genus {\it Halomonas}. The ligand field of Eu(III) on the halophiles was stronger than that on the non-halophiles, indicating that the coordination environment of Eu(III) on the halophiles is dense with the components of the outer cells surface.
DE: 0614 Biological effects
DE: 1065 Trace elements (3670)
SC: Biogeosciences [B]
MN: 2003 Fall Meeting