Identification of the Nickel Uranyl Phosphate Deposits on <i>Citrobacter </i>sp. Cells by Electron Microscopy with Electron Probe X-ray Microanalysis and by Proton-Induced X-ray Emission Analysis

Basnakova, Gabriela; Spencer, A. J.; Pålsgård, Eva; Grime, G.W.; Macaskie, Lynne E.

doi:10.1021/es9705553

Cited by 35 publications

(10 citation statements)

References 26 publications

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“…In all the above studies, a high concentration of phosphate (1.5–5 mM) or bicarbonate buffer (30 mM, pH 7) was used in the growth medium. Phosphate is known to directly precipitate U(VI) phosphate complexes [43,44]. At neutral pH, with 30 mM bicarbonate, U(VI) is almost entirely complexed as UO 2 (CO 3 )

_{2−}^{3}

and UO 2 (CO 3 )

_{4−}^{3}

, with relative fractions of the two complexes being 15 and 85%, respectively [34,45].…”

Section: Discussionmentioning

confidence: 99%

Toxic effects of uranium on Desulfovibrio desulfuricans G20

Sani

Peyton

Dohnálková

2006

Enviro Toxic and Chemistry

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The toxic effects of U(VI) were studied using Desulfovibrio desulfuricans G20 in a medium containing bicarbonate or 1,4-piperazinediethane sulfonic acid disodium salt monohydrate (PIPES) buffer (each at 30 mM and pH 7). Uranium(VI) toxicity was dependent on the medium buffer and was observed in terms of longer lag times and, in some cases, no measurable growth. The minimum inhibiting concentration was 140 microM U(VI) in PIPES-buffered medium. This is 36-fold lower than that reported previously for D. desulfuricans. For all cases in which D. desulfuricans G20 grew in the presence of U(VI), the final cell protein yield was equivalent to that of the U(VI)-free control. In 24 h, D. desulfuricans G20 (total cell protein, 40 mg/L) removed 50 FiM U(VI) from solution in PIPES buffer, as compared to 96 microM U(VI) in bicarbonate buffer under anaerobic, nongrowth conditions. Even though the solubility of U(VI) was significantly lower in PIPES buffer than in bicarbonate buffer, U(VI) was much more toxic in PIPES buffer than in bicarbonate buffer. Analysis of thin sections of D. desulfuricans G20 treated with 90 microM U(VI) in medium containing PIPES buffer revealed that only a very small fraction of cells had reduced U precipitates in the periplasmic spaces. In the presence of bicarbonate buffer, however, reduced U was observed not only in the periplasm but also in the cytoplasm. Selected-area electron diffraction patterns and crystallographic analysis of transmission-electron microscopic lattice fringe images confirmed the structure of precipitated U in the cell periplasm and cytoplasm as being that of uraninite. These results suggest that U(VI) toxicity and the detoxification mechanisms of D. desulfuricans G20 depend greatly on the chemical forms of U(VI) that are present.

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_{2−}^{3}

and UO 2 (CO 3 )

_{4−}^{3}

, with relative fractions of the two complexes being 15 and 85%, respectively [34,45].…”

Section: Discussionmentioning

confidence: 99%

Toxic effects of uranium on Desulfovibrio desulfuricans G20

Sani

Peyton

Dohnálková

2006

Enviro Toxic and Chemistry

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“…Autunite largely controls the mobility of U in soils contaminated by actinides, such as at the Fernald site in Ohio [51], where U was processed during the Cold War, and the U-contaminated K1300 locality of the DOE-K 25 site at Oak Ridge, Tennessee [8]. Autunitegroup minerals are bioprecipitated by Citrobacter sp., which is proposed for remediation of groundwater contaminated by heavy metals [52,53]. They have been found in experiments involving halophilic bacterium isolated from the Waste Isolation Pilot Plant repository [9,10].…”

Section: Uranyl Phosphatesmentioning

confidence: 94%

Review of uranyl mineral solubility measurements

Gorman‐Lewis

Burns

Fein

2008

The Journal of Chemical Thermodynamics

213

144

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“…Proton probe microanalysis has also been used with freshwater specimens (Basnakova et al 1998;Brook et al 1998). This technique has greater element detectability compared with XRMA but has limitations in terms of the complexity of instrumentation.…”

Section: Discussionmentioning

confidence: 99%

Elemental composition of Microcystis aeruginosa under conditions of lake nutrient depletion

2005

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Electron probe X-ray microanalysis (XRMA) was used to determine the elemental composition of the bluegreen alga, Microcystis aeruginosa, in a stratified freshwater lake during the late summer. Colonies of this alga were initially observed in mid-July, at a time when phosphorus concentration in the lake water had decreased to minimal levels (total P 0.04 mg l À1 ). The P quota of these cells was high (mean concentration 132 mmol kg À1 dry weight) with a cell P to lake water P concentration ratio of 10 5 . The elemental concentrations of Microcystis remained relatively stable throughout the sampling period (July-September), with mean cell concentrations of Mg, P, S and Ca showing no significant changes. Mean elemental ratios and the ratio of monovalent/divalent cations were also relatively constant (SE <10% mean). The pattern of cell elemental associations, determined by Factor and Pearson correlation analysis, was consistent throughout -with Mg, P, K and S forming a core tetrad of inter-correlated elements. The relative constancy of cell composition seen in Microcystis would be expected of an alga with a K-selection strategy. The continued high P quota over a period of nutrient depletion in lake water is consistent with the ability of this alga to sink to nutrient-rich lower regions of the water column.

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Identification of the Nickel Uranyl Phosphate Deposits on Citrobacter sp. Cells by Electron Microscopy with Electron Probe X-ray Microanalysis and by Proton-Induced X-ray Emission Analysis

Cited by 35 publications

References 26 publications

Toxic effects of uranium on Desulfovibrio desulfuricans G20

Toxic effects of uranium on Desulfovibrio desulfuricans G20

Review of uranyl mineral solubility measurements

Elemental composition of Microcystis aeruginosa under conditions of lake nutrient depletion

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