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Accession Number DE2013-1064428
Title Effects of Non-Metabolizing Bacterial Cells on the Precipitation of Metal Phosphates.
Publication Date Nov 2011
Media Count 20p
Personal Author B. Bunker J. B. Fein N. Menguy R. Hellmann S. Dunham-Cheatham X. Rui
Abstract In this study, we test the potential for passive cell wall biomineralization by determining the effects of non-metabolizing bacteria on the precipitation of uranyl, lead, and calcium phosphates from a range of over-saturated conditions. Experiments were performed using Gram-positive Bacillus subtilis and Gram-negative Shewanella oneidensis MR-1. After equilibration, the aqueous phases were sampled and the remaining metal and P concentrations were analyzed using inductively coupled plasma-optical emission spectroscopy (ICP-OES); the solid phases were collected and analyzed using X-ray diffractometry (XRD), transmission electron microscopy (TEM), and X-ray absorption spectroscopy (XAS). At the lower degrees of over-saturation studied, bacterial cells exerted no discernable effect on the mode of precipitation of the metal phosphates, with homogeneous precipitation occurring exclusively. However, at higher saturation states in the U system, we observed heterogeneous mineralization and extensive nucleation of hydrogen uranyl phosphate (HUP) mineralization throughout the fabric of the bacterial cell walls. This mineral nucleation effect was observed in both B. subtilis and S. oneidensis cells. In both cases, the biogenic mineral precipitates formed under the higher saturation state conditions were significantly smaller than those that formed in the abiotic controls. The cell wall nucleation effects that occurred in some of the U systems were not observed under any of the saturation state conditions studied in the Pb or Ca systems. The presence of B. subtilis significantly decreased the extent of precipitation in the U system, but had little effect in the Pb and Ca systems. At least part of this effect is due to higher solubility of the nanoscale HUP precipitate relative to macroscopic HUP. This study documents several effects of non-metabolizing bacterial cells on the nature and extent of metal phosphate precipitation.
Keywords Bacteria
Calcium
Electron microscopy
Emission spectroscopy
Lead
Metals
Phosphates
Precipitation
Solid phases
Uranyl
X-ray diffraction


 
Source Agency Technical Information Center Oak Ridge Tennessee
NTIS Subject Category 57K - Microbiology
71 - Materials Sciences
99F - Physical & Theoretical Chemistry
Corporate Author Notre Dame Univ., IN.
Document Type Technical report
Title Note N/A
NTIS Issue Number 1323
Contract Number DE-FG02-07ER64395

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