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1 PublicationBio-precipitation of uranium by two bacterial isolates recovered from extreme environments as estimated by potentiometric titration, TEM and X-ray absorption spectroscopic analyses
Merroun, M. L.; Nedelkova, M.; Ojeda, J. J.; Reitz, T.; Fernandez, M. L.; Arias, J. M.; Romero-Gonzalez, M.; Selenska-Pobell, S.
Abstract
This work describes the mechanisms of uranium biomineralization at acidic conditions by Bacillus sphaericus JG-7B and Sphingomonas sp. S15-S1 both recovered from extreme environments. The U bacterial interaction experiments were performed at low pH values (2.0-4.5) and using 0.1 M NaClO4 as electrolyte background where the uranium aqueous speciation is dominated by the free uranyl ion. As demonstrated by X-ray absorption (XAS) studies, the cells of the studied strains precipitated uranium at pH 3.0 and 4.5 as a uranium phosphate mineral phase belonging to the meta-autunite group. The observed U(VI) biomineralization was associated with the activity of indigenous acid phosphatase detected at these pH values without the supply of an organic phosphate substrate. At pH 2.0, however, no uranium biomineralization occurred, and U(VI) formed complexes with organically bound phosphates of the cells. Transmission electron microscopic (TEM) analyses showed strain-specific localization of the uranium precipitates. In the case of B. sphaericus JG-7B U(VI) was bound to the cell wall while in the case of Sphingomonas sp. S15-S1, U(VI) precipitates were found not only on the cell surface but also intracellularly. This study contributes to the expansion of the number of bacterial strains that have been demonstrated to precipitate uranium phosphates at acidic conditions via the activity of acid phosphatase.
Keywords: Uranium biomineralization; Potentiometric titration; XAS; TEM/EDX; Acid phosphatase
Involved research facilities
- Rossendorf Beamline at ESRF DOI: 10.1107/S1600577520014265
Related publications
- DOI: 10.1107/S1600577520014265 is cited by this (Id 16137) publication
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Journal of Hazardous Materials 197(2011), 1-10
DOI: 10.1016/j.jhazmat.2011.09.049
Cited 91 times in Scopus
Permalink: https://www.hzdr.de/publications/Publ-16137