Bio-precipitation of uranium by two bacterial isolates recovered from extreme environments as estimated by potentiometric titration, TEM and X-ray absorption spectroscopic analyses

JOURNAL OF HAZARDOUS MATERIALS

卷:197

Article

Merroun, Mohamed L.^1,2  Nedelkova, Marta²  Ojeda, Jesus J.^3,4  Reitz, Thomas^2,5  Lopez Fernandez, Margarita¹  Arias, Jose M.¹  Romero-Gonzalez, Maria³  Selenska-Pobell, Sonja² 

[1] Univ Granada, Dept Microbiol, E-18071 Granada, Spain

[2] Helmholtz Ctr Dresden Rossendorf, Inst Radiochem, Dresden, Germany

[3] Univ Sheffield, Kroto Res Inst, Cell Mineral Interface Res Programme, Sheffield S3 7HQ, S Yorkshire, England

[4] Brunel Univ, Expt Tech Ctr, Uxbridge UB8 3PH, Middx, England

[5] UFZ Helmholtz Ctr Environm Res, Dept Soil Ecol, Halle, Germany

关键词: Uranium biomineralization;    Potentiometric titration;    XAS;    TEM/EDX;    Acid phosphatase;   

DOI  :  10.1016/j.jhazmat.2011.09.049

来源: Elsevier

【 摘 要 】

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) where the uranium aqueous speciation is dominated by highly mobile uranyl ions. X-ray absorption spectroscopy (XAS) showed that 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. Transmission electron microscopic (TEM) analyses showed strain-specific localization of the uranium precipitates. In the case of B. sphaericus JG-7B, the U(VI) precipitate was bound to the cell wall. Whereas for Sphingomonas sp. S15-S1, the U(VI) precipitates were observed both on the cell surface and intracellularly. The observed U(VI) biomineralization was associated with the activity of indigenous acid phosphatase detected at these pH values in the absence of an organic phosphate substrate. The biomineralization of uranium was not observed at pH 2.0, and U(VI) formed complexes with organophosphate ligands from the cells. This study increases the number of bacterial strains that have been demonstrated to precipitate uranium phosphates at acidic conditions via the activity of acid phosphatase. (C) 2011 Elsevier B.V. All rights reserved.

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