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Uranium Biominerals Precipitated by an Environmental Isolate of Serratia under Anaerobic Conditions.

Newsome L, Morris K, Lloyd JR - PLoS ONE (2015)

Bottom Line: Here we present the results of uranium biomineralisation experiments using an isolate of Serratia obtained from a sediment sample representative of the Sellafield nuclear site, UK.Under phosphate-limited anaerobic conditions and with glycerol as the electron donor, non-growing Serratia cells could precipitate 0.5 mM of uranium supplied as soluble U(VI), via reduction to nano-crystalline U(IV) uraninite.Some evidence for the reduction of solid phase uranyl(VI) phosphate was also observed.

View Article: PubMed Central - PubMed

Affiliation: Research Centre for Radwaste Disposal and Williamson Research Centre, School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Oxford Road, Manchester, United Kingdom.

ABSTRACT
Stimulating the microbially-mediated precipitation of uranium biominerals may be used to treat groundwater contamination at nuclear sites. The majority of studies to date have focussed on the reductive precipitation of uranium as U(IV) by U(VI)- and Fe(III)-reducing bacteria such as Geobacter and Shewanella species, although other mechanisms of uranium removal from solution can occur, including the precipitation of uranyl phosphates via bacterial phosphatase activity. Here we present the results of uranium biomineralisation experiments using an isolate of Serratia obtained from a sediment sample representative of the Sellafield nuclear site, UK. When supplied with glycerol phosphate, this Serratia strain was able to precipitate 1 mM of soluble U(VI) as uranyl phosphate minerals from the autunite group, under anaerobic and fermentative conditions. Under phosphate-limited anaerobic conditions and with glycerol as the electron donor, non-growing Serratia cells could precipitate 0.5 mM of uranium supplied as soluble U(VI), via reduction to nano-crystalline U(IV) uraninite. Some evidence for the reduction of solid phase uranyl(VI) phosphate was also observed. This study highlights the potential for Serratia and related species to play a role in the bioremediation of uranium contamination, via a range of different metabolic pathways, dependent on culturing or in situ conditions.

No MeSH data available.


Related in: MedlinePlus

Microbial U(VI)s reduction experiment: TEM images (a, b, c), k3 weighted EXAFS data (d), non-phase shift corrected Fourier transform of EXAFS data (e) and XRD spectra (f).Dashed lines in XAS spectra represent the best fit of the data. * are peaks from uranyl phosphates (S6 Fig shows the peak pattern). Experiments were conducted in a bicarbonate buffer with glycerol as the electron donor and microbially precipitated U(VI) phosphate (Fig 2) as the electron acceptor. Results confirmed the precipitate to be a uranyl phosphate biomineral of the autunite group, with some evidence for partial transformation to a uraninite-like U(IV) phase.
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pone.0132392.g006: Microbial U(VI)s reduction experiment: TEM images (a, b, c), k3 weighted EXAFS data (d), non-phase shift corrected Fourier transform of EXAFS data (e) and XRD spectra (f).Dashed lines in XAS spectra represent the best fit of the data. * are peaks from uranyl phosphates (S6 Fig shows the peak pattern). Experiments were conducted in a bicarbonate buffer with glycerol as the electron donor and microbially precipitated U(VI) phosphate (Fig 2) as the electron acceptor. Results confirmed the precipitate to be a uranyl phosphate biomineral of the autunite group, with some evidence for partial transformation to a uraninite-like U(IV) phase.

Mentions: The majority of the TEM images were dominated by dense agglomerations of sheets of mineral (Fig 6), similar to the amorphous autunite group mineral that was added to these experiments as the starting material (Fig 2). However, a considerable number of areas comprised clusters of a different material, 2–3 nm in size (Fig 6) that resembled the uraninite from the U(VI) reduction experiments (Fig 5). This suggests that the original uranyl phosphate had been partially altered by the Serratia species. XRD analysis identified the mineral to be uranyl phosphate (Fig 6), although it is difficult for this technique to detect the presence of a small amount of nanocrystalline mineral within a bulk mineral phase.


Uranium Biominerals Precipitated by an Environmental Isolate of Serratia under Anaerobic Conditions.

Newsome L, Morris K, Lloyd JR - PLoS ONE (2015)

Microbial U(VI)s reduction experiment: TEM images (a, b, c), k3 weighted EXAFS data (d), non-phase shift corrected Fourier transform of EXAFS data (e) and XRD spectra (f).Dashed lines in XAS spectra represent the best fit of the data. * are peaks from uranyl phosphates (S6 Fig shows the peak pattern). Experiments were conducted in a bicarbonate buffer with glycerol as the electron donor and microbially precipitated U(VI) phosphate (Fig 2) as the electron acceptor. Results confirmed the precipitate to be a uranyl phosphate biomineral of the autunite group, with some evidence for partial transformation to a uraninite-like U(IV) phase.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4488441&req=5

pone.0132392.g006: Microbial U(VI)s reduction experiment: TEM images (a, b, c), k3 weighted EXAFS data (d), non-phase shift corrected Fourier transform of EXAFS data (e) and XRD spectra (f).Dashed lines in XAS spectra represent the best fit of the data. * are peaks from uranyl phosphates (S6 Fig shows the peak pattern). Experiments were conducted in a bicarbonate buffer with glycerol as the electron donor and microbially precipitated U(VI) phosphate (Fig 2) as the electron acceptor. Results confirmed the precipitate to be a uranyl phosphate biomineral of the autunite group, with some evidence for partial transformation to a uraninite-like U(IV) phase.
Mentions: The majority of the TEM images were dominated by dense agglomerations of sheets of mineral (Fig 6), similar to the amorphous autunite group mineral that was added to these experiments as the starting material (Fig 2). However, a considerable number of areas comprised clusters of a different material, 2–3 nm in size (Fig 6) that resembled the uraninite from the U(VI) reduction experiments (Fig 5). This suggests that the original uranyl phosphate had been partially altered by the Serratia species. XRD analysis identified the mineral to be uranyl phosphate (Fig 6), although it is difficult for this technique to detect the presence of a small amount of nanocrystalline mineral within a bulk mineral phase.

Bottom Line: Here we present the results of uranium biomineralisation experiments using an isolate of Serratia obtained from a sediment sample representative of the Sellafield nuclear site, UK.Under phosphate-limited anaerobic conditions and with glycerol as the electron donor, non-growing Serratia cells could precipitate 0.5 mM of uranium supplied as soluble U(VI), via reduction to nano-crystalline U(IV) uraninite.Some evidence for the reduction of solid phase uranyl(VI) phosphate was also observed.

View Article: PubMed Central - PubMed

Affiliation: Research Centre for Radwaste Disposal and Williamson Research Centre, School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Oxford Road, Manchester, United Kingdom.

ABSTRACT
Stimulating the microbially-mediated precipitation of uranium biominerals may be used to treat groundwater contamination at nuclear sites. The majority of studies to date have focussed on the reductive precipitation of uranium as U(IV) by U(VI)- and Fe(III)-reducing bacteria such as Geobacter and Shewanella species, although other mechanisms of uranium removal from solution can occur, including the precipitation of uranyl phosphates via bacterial phosphatase activity. Here we present the results of uranium biomineralisation experiments using an isolate of Serratia obtained from a sediment sample representative of the Sellafield nuclear site, UK. When supplied with glycerol phosphate, this Serratia strain was able to precipitate 1 mM of soluble U(VI) as uranyl phosphate minerals from the autunite group, under anaerobic and fermentative conditions. Under phosphate-limited anaerobic conditions and with glycerol as the electron donor, non-growing Serratia cells could precipitate 0.5 mM of uranium supplied as soluble U(VI), via reduction to nano-crystalline U(IV) uraninite. Some evidence for the reduction of solid phase uranyl(VI) phosphate was also observed. This study highlights the potential for Serratia and related species to play a role in the bioremediation of uranium contamination, via a range of different metabolic pathways, dependent on culturing or in situ conditions.

No MeSH data available.


Related in: MedlinePlus