Enzymically mediated bioprecipitation of uranium by a Citrobacter sp.: a concerted role for exocellular lipopolysaccharide and associated phosphatase in biomineral formation

Macaskie, Lynne E.; Bonthrone, Karen M.; Yong, Ping; Goddard, D. T.

doi:10.1099/00221287-146-8-1855

Cited by 213 publications

(126 citation statements)

References 54 publications

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“…Citrobacter (bacteria) precipitates U(VI) and other heavy metals on its cell surfaces as metal phosphates (Roig et al, 1997). Macaskie et al (2000) describe the process whereby Citrobacter produces an overabundance of alkaline phosphatase, which in turn causes the cells to excrete phosphate, which provides the nucleus for the precipitation of U(VI) phosphate on cell surfaces.…”

Section: Bio-precipitationmentioning

confidence: 99%

The removal of uranium from mining waste water using algal/microbial biomass

Kalin¹,

Wheeler²,

Meinrath³

2005

Journal of Environmental Radioactivity

305

134

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We describe a three step process for the removal of uranium (U) from dilute waste waters.Step one involves the sequestration of U on, in, and around aquatic plants such as algae. Cell wall ligands efficiently remove U(VI) from waste water. Growing algae continuously renew the cellular surface area.Step 2 is the removal of U-algal particulates from the water column to the sediments.Step 3 involves reducing U(VI) to U(IV) and transforming the ions into stable precipitates in the sediments. The algal cells provide organic carbon and other nutrients to heterotrophic microbial consortia to maintain the low E H , within which the U is transformed.Among the microorganisms, algae are of predominant interest for the ecological engineer because of their ability to sequester U and because some algae can live under many extreme environments, often in abundance. Algae grow in a wide spectrum of water qualities, from alkaline environments (Chara, Nitella) to acidic mine drainage waste waters (Mougeotia, Ulothrix). If they could be induced to grow in waste waters, they would provide a simple, longterm means to remove U and other radionuclides from U mining effluents. This paper reviews the literature on algal and microbial adsorption, reduction, and transformation of U in waste streams, wetlands, lakes and oceans.

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Section: Bio-precipitationmentioning

confidence: 99%

The removal of uranium from mining waste water using algal/microbial biomass

Kalin¹,

Wheeler²,

Meinrath³

2005

Journal of Environmental Radioactivity

305

134

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“…For example, organic molecules exuded by biofilms widely affect the precipitation of calcite, influencing not only the growth kinetics, but the morphology as well (Mann et al, 1990;Archibald et al, 1996;McGrath, 2001;Meldrum and Hyde, 2001;Braissant et al, 2003;Hammes et al, 2003;Tong et al, 2004;Bosak and Newman, 2005;Dupraz et al, 2009), likely through incorporation effects (Lowenstam and Weiner, 1989). Studies have also shown that various organic molecules widely affect the structure and morphology of a range of minerals, including numerous iron oxides (Châtellier et al, 2001(Châtellier et al, , 2004Larese-Casanova et al, 2010;Perez-Gonzalez et al, 2010), uranyl phosphate (Macaskie et al, 2000), and silica (Williams, 1984).…”

Section: Introductionmentioning

confidence: 99%

“…Both field (Ferris et al, 1987;Konhauser et al, 1993;Bonny and Jones, 2003;Fortin and Langley, 2005;Demergasso et al, 2007) and laboratory (Macaskie et al, 2000;Warren et al, 2001;Rivadeneyra et al, 2006) studies have examined mineral formation in super-saturated systems and have found a close spatial association between bacterial cells and a range of extracellular precipitated mineral phases. Despite the increasing number of studies to claim the importance of passive cell wall biomineralization (Lowenstam and Weiner, 1989;Châtellier et al, 2001;Ben Chekroun et al, 2004;Beazley et al, 2007;Dupraz et al, 2009), the nature of the evidence to date is equivocal.…”

Section: Introductionmentioning

confidence: 99%

The effects of non-metabolizing bacterial cells on the precipitation of U, Pb and Ca phosphates

Dunham‐Cheatham

Xue

Bunker

et al. 2011

Geochimica et Cosmochimica Acta

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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 plasmaoptical 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. Each of these effects likely contributes to higher metal mobilities in geologic media, but the effects are not universal, and occur only with some elements and only under a subset of the conditions studied.

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“…Many resistance mechanisms revolve around removing the heavy metal or decreasing its toxicity (70). Alternatively, the concentration of metal entering the cytoplasm may be decreased through active (extracellular precipitation) and passive (native biosorption) processes (30,35). Metal-chelating proteins have been reported as a means of resistance mainly in eukaryotes and also in some limited examples of prokaryotes (70).…”

mentioning

confidence: 99%

“…Metal-chelating proteins have been reported as a means of resistance mainly in eukaryotes and also in some limited examples of prokaryotes (70). The major bacterial resistance mechanisms include (i) active efflux, (ii) transformation of the heavy metal ion to a less toxic form, for example, Cr(VI) can be reduced to Cr(III) (12), and (iii) precipitation, either intercellular or extracellular (35,64,66,67). Caulobacter spp.…”

mentioning

confidence: 99%

Whole-Genome Transcriptional Analysis of Heavy Metal Stresses in Caulobacter crescentus

et al. 2005

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The bacterium Caulobacter crescentus and related stalk bacterial species are known for their distinctive ability to live in low-nutrient environments, a characteristic of most heavy metal-contaminated sites. Caulobacter crescentus is a model organism for studying cell cycle regulation with well-developed genetics. We have identified the pathways responding to heavy-metal toxicity in C. crescentus to provide insights for the possible application of Caulobacter to environmental restoration. We exposed C. crescentus cells to four heavy metals (chromium, cadmium, selenium, and uranium) and analyzed genome-wide transcriptional activities postexposure using an Affymetrix GeneChip microarray. C. crescentus showed surprisingly high tolerance to uranium, a possible mechanism for which may be the formation of extracellular calcium-uranium-phosphate precipitates. The principal response to these metals was protection against oxidative stress (up-regulation of manganese-dependent superoxide dismutase sodA). Glutathione S-transferase, thioredoxin, glutaredoxins, and DNA repair enzymes responded most strongly to cadmium and chromate. The cadmium and chromium stress response also focused on reducing the intracellular metal concentration, with multiple efflux pumps employed to remove cadmium, while a sulfate transporter was down-regulated to reduce nonspecific uptake of chromium. Membrane proteins were also up-regulated in response to most of the metals tested. A two-component signal transduction system involved in the uranium response was identified. Several differentially regulated transcripts from regions previously not known to encode proteins were identified, demonstrating the advantage of evaluating the transcriptome by using whole-genome microarrays.Potentially hazardous levels of heavy metals have dispersed into subsurface sediment and groundwater in a number of metal-contaminated sites and represent a challenge for environmental restoration. Effective bioremediation of these sites requires knowledge of genetic pathways for resistance and biotransformation by component organisms within a microbial community. However, a comprehensive understanding of bacterial mechanisms of heavy metal toxicity and resistance has yet to be achieved. While many metals are essential to microbial function, heavy metals, i.e., most of those with a density above 5 g/cm 3 , have toxic effects on cellular metabolism (46). The majority of heavy metals are transition elements with incompletely filled d orbitals providing heavy metal cations which can form complex compounds with redox activity (46,70). Therefore, it is important to the health of the organism that the intracellular concentrations of heavy metal ions are tightly controlled. However, due to their structural and valence similarities to nontoxic metals, heavy metals are often transported into the cytoplasm through constitutively expressed nonspecific transport systems (46). As such, heavy metals invariably find their way into the cell. Once inside the cell, toxic effects of heavy metals...

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Enzymically mediated bioprecipitation of uranium by a Citrobacter sp.: a concerted role for exocellular lipopolysaccharide and associated phosphatase in biomineral formation

Cited by 213 publications

References 54 publications

The removal of uranium from mining waste water using algal/microbial biomass

The removal of uranium from mining waste water using algal/microbial biomass

The effects of non-metabolizing bacterial cells on the precipitation of U, Pb and Ca phosphates

Whole-Genome Transcriptional Analysis of Heavy Metal Stresses in Caulobacter crescentus

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