Potential for Bioremediation of Uranium-Contaminated Aquifers with Microbial U(VI) Reduction

Finneran, Kevin T.; Anderson, Robert; Nevin, Kelly P.; Lovley, Derek R.

doi:10.1080/20025891106781

Cited by 238 publications

(207 citation statements)

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“…Accordingly, U contaminated settings such as mine sites, mill tailings, and sites where nuclear weapons have been manufactured have been studied directly by field observations or indirectly in laboratory experiments in which sediment and water samples collected from the field have been used to simulate in situ biogeochemical processes. The laboratory amendment of field sediments with organic substrates as electron donors to stimulate anaerobic microbial respiration typically results in significant removal of U from the pore water within a short period (< 1 month) (Abdelouas et al, 1999;Abdelouas et al, 2000;Finneran et al, 2002a;Finneran et al, 2002b;Suzuki et al, 2002;Elias et al, 2003a;Nevin et al, 2003;Suzuki et al, 2003;North et al, 2004;Gu et al, 2005a;Senko et al, 2005b;Tokunaga et al, 2005;Wan et al, 2005). No U(VI) reduction has been observed in the abiological controls, which strongly suggests that U(VI) reduction is biologically mediated.…”

Section: Redox Transformations Of U In U-contaminated Settingsmentioning

confidence: 88%

Geomicrobiological factors that control uranium mobility in the environment: Update on recent advances in the bioremediation of uranium-contaminated sites

Suzuki

Suko

2006

Journal of Mineralogical and Petrological Sciences

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Understanding the behavior of uranium (U) in the environment is essential not only for the protection of aquifers from U contamination but also for predicting the fate of U and other actinides disposed of in deep geological settings. It has long been believed that the redox chemistry of U can be simply predicted by thermodynamics and that the development of a low redox potential is a sufficient condition for U reduction. However, recent studies have demonstrated that redox transformations of U are controlled by kinetic factors that are strongly influenced by microbial activity. Although abiological U oxidation proceeds efficiently under oxygenic conditions, abiological reduction of U is inhibited by the formation of negatively charged U(VI) CO 3 complexes that prevail in nature. Phylogenetically diverse microorganisms are capable of enzymatically reducing U(VI) CO 3 complexes to form U(IV) bearing minerals such as uraninite (UO 2+x . This complex is mainly produced by the microbial reduction of Fe(III) in natural systems. Thus, U(VI) reduction is controlled both directly and indirectly, at least in part, by microbial activity. Several mechanisms of U oxidation under anoxic conditions have been revealed recently by laboratory and field studies. U(IV) is abiologically oxidized by Fe(III) and Mn(IV) oxides. Microbial reduction of nitrate to molecular nitrogen, which occurs following the depletion of O 2 , produces nitrogen intermediates including nitrite (NO 2 -), nitrous oxide (NO), and nitric oxide (N 2 O). Although the nitrogen intermediates oxidize U(IV), poorly crystalline Fe(III) oxide minerals resulting from the oxidation of aqueous Fe(II) species by the nitrogen intermediates oxidize U(IV) more efficiently than the nitrogen intermediates alone. Remarkably, the formation of Ca U(VI) CO 3 complexes resulting from increased levels of Ca 2+ and/or HCO 3 -leads to the reoxidation of bioreduced U(IV) under reducing conditions. These geomicrobiological factors pose challenges in manipulating and/or predicting the mobility and fate of U in complex and heterogeneous environmental settings.

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Section: Redox Transformations Of U In U-contaminated Settingsmentioning

confidence: 88%

Geomicrobiological factors that control uranium mobility in the environment: Update on recent advances in the bioremediation of uranium-contaminated sites

Suzuki

Suko

2006

Journal of Mineralogical and Petrological Sciences

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“…This was associated with a marked increase in the abundance of Geobacter species in the groundwater (Elifantz et al, 2008;Mouser et al, 2009b). Geobacter species are known Fe(III)-and U(VI)-reducing microorganisms and are considered to be responsible for most of the dissimilatory metal reduction in these acetate-amended subsurface sediments (Lovley, 1991;Finneran et al, 2002;Holmes et al, 2002Holmes et al, , 2005Anderson et al, 2003;Istok et al, 2004;Vrionis et al, 2005). Within a period of 20 days of acetate addition, the uranium concentration in D02 was reduced by more than 80%, starting at an initial background concentration of about 130 mg l À1 and diminishing to values well below the EPA maximum contaminant level (30 mg l À1 ) by the end of the study period (Figure 2c).…”

Section: Resultsmentioning

confidence: 99%

Molecular analysis of phosphate limitation in Geobacteraceae during the bioremediation of a uranium-contaminated aquifer

et al. 2009

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Nutrient limitation is an environmental stress that may reduce the effectiveness of bioremediation strategies, especially when the contaminants are organic compounds or when organic compounds are added to promote microbial activities such as metal reduction. Genes indicative of phosphatelimitation were identified by microarray analysis of chemostat cultures of Geobacter sulfureducens. This analysis revealed that genes in the pst-pho operon, which is associated with a high-affinity phosphate uptake system in other microorganisms, had significantly higher transcript abundance under phosphate-limiting conditions, with the genes pstB and phoU upregulated the most. Quantitative PCR analysis of pstB and phoU transcript levels in G. sulfurreducens grown in chemostats demonstrated that the expression of these genes increased when phosphate was removed from the culture medium. Transcripts of pstB and phoU within the subsurface Geobacter species predominating during an in situ uranium-bioremediation field experiment were more abundant than in chemostat cultures of G. sulfurreducens that were not limited for phosphate. Addition of phosphate to incubations of subsurface sediments did not stimulate dissimilatory metal reduction. The added phosphate was rapidly adsorbed onto the sediments. The results demonstrate that Geobacter species can effectively reduce U(VI) even when experiencing suboptimal phosphate concentrations and that increasing phosphate availability with phosphate additions is difficult to achieve because of the high reactivity of this compound. This transcript-based approach developed for diagnosing phosphate limitation should be applicable to assessing the potential need for additional phosphate in other bioremediation processes.

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“…For example, a strategy for bioremediation of uraniumcontaminated groundwater is to accelerate the growth of Geobacter species with the addition of acetate to promote reductive precipitation of uranium (Anderson et al, 2003;Chang et al, 2005;N'Guessan et al, 2008). Studies with Geobacter sulfurreducens demonstrated that selective pressure for faster growth on Fe(III) oxides, the primary electron acceptor supporting Geobacter growth during uranium bioremediation (Finneran et al, 2002), resulted in replicate strains, which accumulated mutations that increased the production of microbial pili (Reguera et al, 2005(Reguera et al, , 2006 and other proteins that enhance the rate of Fe(III) oxide reduction (Tremblay et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Laboratory evolution of Geobacter sulfurreducens for enhanced growth on lactate via a single-base-pair substitution in a transcriptional regulator

et al. 2011

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The addition of organic compounds to groundwater in order to promote bioremediation may represent a new selective pressure on subsurface microorganisms. The ability of Geobacter sulfurreducens, which serves as a model for the Geobacter species that are important in various types of anaerobic groundwater bioremediation, to adapt for rapid metabolism of lactate, a common bioremediation amendment, was evaluated. Serial transfer of five parallel cultures in a medium with lactate as the sole electron donor yielded five strains that could metabolize lactate faster than the wild-type strain. Genome sequencing revealed that all five strains had non-synonymous single-nucleotide polymorphisms in the same gene, GSU0514, a putative transcriptional regulator. Introducing the single-base-pair mutation from one of the five strains into the wild-type strain conferred rapid growth on lactate. This strain and the five adaptively evolved strains had four to eight-fold higher transcript abundance than wild-type cells for genes for the two subunits of succinyl-CoA synthase, an enzyme required for growth on lactate. DNA-binding assays demonstrated that the protein encoded by GSU0514 bound to the putative promoter of the succinyl-CoA synthase operon. The binding sequence was not apparent elsewhere in the genome. These results demonstrate that a single-base-pair mutation in a transcriptional regulator can have a significant impact on the capacity for substrate utilization and suggest that adaptive evolution should be considered as a potential response of microorganisms to environmental change(s) imposed during bioremediation.

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Potential for Bioremediation of Uranium-Contaminated Aquifers with Microbial U(VI) Reduction

Cited by 238 publications

References 0 publications

Geomicrobiological factors that control uranium mobility in the environment: Update on recent advances in the bioremediation of uranium-contaminated sites

Geomicrobiological factors that control uranium mobility in the environment: Update on recent advances in the bioremediation of uranium-contaminated sites

Molecular analysis of phosphate limitation in Geobacteraceae during the bioremediation of a uranium-contaminated aquifer

Laboratory evolution of Geobacter sulfurreducens for enhanced growth on lactate via a single-base-pair substitution in a transcriptional regulator

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