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Williamson AJ, Binet M, Sergeant C. Radionuclide biogeochemistry: from bioremediation toward the treatment of aqueous radioactive effluents. Crit Rev Biotechnol 2024; 44:698-716. [PMID: 37258417 DOI: 10.1080/07388551.2023.2194505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 10/07/2022] [Accepted: 01/29/2023] [Indexed: 06/02/2023]
Abstract
Civilian and military nuclear programs of several nations over more than 70 years have led to significant quantities of heterogenous solid, organic, and aqueous radioactive wastes bearing actinides, fission products, and activation products. While many physicochemical treatments have been developed to remediate, decontaminate and reduce waste volumes, they can involve high costs (energy input, expensive sorbants, ion exchange resins, chemical reducing/precipitation agents) or can lead to further secondary waste forms. Microorganisms can directly influence radionuclide solubility, via sorption, accumulation, precipitation, redox, and volatilization pathways, thus offering a more sustainable approach to remediation or effluent treatments. Much work to date has focused on fundamentals or laboratory-scale remediation trials, but there is a paucity of information toward field-scale bioremediation and, to a lesser extent, toward biological liquid effluent treatments. From the few biostimulation studies that have been conducted at legacy weapon production/test sites and uranium mining and milling sites, some marked success via bioreduction and biomineralisation has been observed. However, rebounding of radionuclide mobility from (a)biotic scale-up factors are often encountered. Radionuclide, heavy metal, co-contaminant, and/or matrix effects provide more challenging conditions than traditional industrial wastewater systems, thus innovative solutions via indirect interactions with stable element biogeochemical cycles, natural or engineered cultures or communities of metal and irradiation tolerant strains and reactor design inspirations from existing metal wastewater technologies, are required. This review encompasses the current state of the art in radionuclide biogeochemistry fundamentals and bioremediation and establishes links toward transitioning these concepts toward future radioactive effluent treatments.
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Affiliation(s)
| | - Marie Binet
- EDF R&D, LNHE (Laboratoire National d'Hydraulique et Environnement), Chatou, France
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2
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Merino N, Wasserman NL, Coutelot F, Kaplan DI, Powell BA, Jiao Y, Kersting AB, Zavarin M. Microbial community dynamics and cycling of plutonium and iron in a seasonally stratified and radiologically contaminated pond. Sci Rep 2023; 13:19697. [PMID: 37952079 PMCID: PMC10640648 DOI: 10.1038/s41598-023-45182-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Accepted: 10/17/2023] [Indexed: 11/14/2023] Open
Abstract
Plutonium (Pu) cycling and mobility in the environment can be impacted by the iron cycle and microbial community dynamics. We investigated the spatial and temporal changes of the microbiome in an iron (Fe)-rich, plutonium-contaminated, monomictic reservoir (Pond B, Savannah River Site, South Carolina, USA). The microbial community composition varied with depth during seasonal thermal stratification and was strongly correlated with redox. During stratification, Fe(II) oxidizers (e.g., Ferrovum, Rhodoferax, Chlorobium) were most abundant in the hypoxic/anoxic zones, while Fe(III) reducers (e.g., Geothrix, Geobacter) dominated the deep, anoxic zone. Sulfate reducers and methanogens were present in the anoxic layer, likely contributing to iron and plutonium cycling. Multinomial regression of predicted functions/pathways identified metabolisms highly associated with stratification (within the top 5%), including iron reduction, methanogenesis, C1 compound utilization, fermentation, and aromatic compound degradation. Two sediment cores collected at the Inlet and Outlet of the pond were dominated by putative fermenters and organic matter (OM) degraders. Overall, microbiome analyses revealed the potential for three microbial impacts on the plutonium and iron biogeochemical cycles: (1) plutonium bioaccumulation throughout the water column, (2) Pu-Fe-OM-aggregate formation by Fe(II) oxidizers under microaerophilic/aerobic conditions, and (3) Pu-Fe-OM-aggregate or sediment reductive dissolution and organic matter degradation in the deep, anoxic waters.
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Affiliation(s)
- Nancy Merino
- Glenn T. Seaborg Institute, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, CA, 94550, USA.
| | - Naomi L Wasserman
- Glenn T. Seaborg Institute, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, CA, 94550, USA
| | - Fanny Coutelot
- Department of Environmental Engineering and Earth Sciences, Clemson University, Anderson, SC, 29625, USA
- Center for Nuclear Environmental Engineering Sciences and Radioactive Waste Management, Clemson University, Anderson, SC, 29625, USA
| | - Daniel I Kaplan
- Savannah River Ecology Lab, University of Georgia, Aiken, SC, 29802, USA
| | - Brian A Powell
- Department of Environmental Engineering and Earth Sciences, Clemson University, Anderson, SC, 29625, USA
- Center for Nuclear Environmental Engineering Sciences and Radioactive Waste Management, Clemson University, Anderson, SC, 29625, USA
- Savannah River National Laboratory, Aiken, SC, 29625, USA
| | - Yongqin Jiao
- Glenn T. Seaborg Institute, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, CA, 94550, USA
| | - Annie B Kersting
- Glenn T. Seaborg Institute, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, CA, 94550, USA
| | - Mavrik Zavarin
- Glenn T. Seaborg Institute, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, CA, 94550, USA.
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Global Transcriptional Response of Escherichia coli Exposed In Situ to Different Low-Dose Ionizing Radiation Sources. mSystems 2023; 8:e0071822. [PMID: 36779725 PMCID: PMC10134817 DOI: 10.1128/msystems.00718-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023] Open
Abstract
Characterization of biological and chemical responses to ionizing radiation by various organisms is essential for potential applications in bioremediation, alternative modes of detecting nuclear material, and national security. Escherichia coli DH10β is an optimal system to study the microbial response to low-dose ionizing radiation at the transcriptional level because it is a well-characterized model bacterium and its responses to other environmental stressors, including those to higher radiation doses, have been elucidated in prior studies. In this study, RNA sequencing with downstream transcriptomic analysis (RNA-seq) was employed to characterize the global transcriptional response of stationary-phase E. coli subjected to 239Pu, 3H (tritium), and 55Fe, at an approximate absorbed dose rate of 10 mGy day-1 for 1 day and 15 days. Differential expression analysis identified significant changes in gene expression of E. coli for both short- and long-term exposures. Radionuclide source exposure induced differential expression in E. coli of genes involved in biosynthesis pathways of nuclear envelope components, amino acids, and siderophores, transport systems such as ABC transporters and type II secretion proteins, and initiation of stress response and regulatory systems of temperature stress, the RpoS regulon, and oxidative stress. These findings provide a basic understanding of the relationship between low-dose exposure and biological effect of a model bacterium that is critical for applications in alternative nuclear material detection and bioremediation. IMPORTANCE Escherichia coli strain DH10β, a well-characterized model bacterium, was subjected to short-term (1-day) and long-term (15-day) exposures to three different in situ radiation sources comprised of radionuclides relevant to nuclear activities to induce a measurable and identifiable genetic response. We found E. coli had both common and unique responses to the three exposures studied, suggesting both dose rate- and radionuclide-specific effects. This study is the first to provide insights into the transcriptional response of a microorganism in short- and long-term exposure to continuous low-dose ionizing radiation with multiple in situ radionuclide sources and the first to examine microbial transcriptional response in stationary phase. Moreover, this work provides a basis for the development of biosensors and informing more robust dose-response relationships to support ecological risk assessment.
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Zelenina D, Kuzmenkova N, Sobolev D, Boldyrev K, Namsaraev Z, Artemiev G, Samylina O, Popova N, Safonov A. Biogeochemical Factors of Cs, Sr, U, Pu Immobilization in Bottom Sediments of the Upa River, Located in the Zone of Chernobyl Accident. BIOLOGY 2022; 12:biology12010010. [PMID: 36671703 PMCID: PMC9854679 DOI: 10.3390/biology12010010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Revised: 12/14/2022] [Accepted: 12/17/2022] [Indexed: 12/24/2022]
Abstract
Laboratory modeling of Cs, Sr, U, Pu immobilization by phytoplankton of the river Upa, affected after the Chernobyl accident, has been carried out. Certain conditions are selected for strong fixation of radionuclides in bottom sediments due to biogeochemical processes. The process of radionuclide removal from the water phase via precipitation was based on their accumulation by phytoplankton, stimulated by nitrogen and phosphorus sources. After eight days of stimulation, planktonic phototrophic biomass, dominated by cyanobacteria of the genus Planktothrix, appears in the water sample. The effectiveness of U, Pu and Sr purification via their transfer to bottom sediment was observed within one month. The addition of ammonium sulfate and phosphate (Ammophos) led to the activation of sulfate- and iron-reducing bacteria of the genera Desulfobacterota, Desulfotomaculum, Desulfosporomusa, Desulfosporosinus, Thermodesulfobium, Thiomonas, Thiobacillus, Sulfuritallea, Pseudomonas, which form sulphide ferrous precipitates such as pyrite, wurtzite, hydrotroillite, etc., in anaerobic bottom sediments. The biogenic mineral composition of the sediments obtained under laboratory conditions was verified via thermodynamic modeling.
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Affiliation(s)
- Darya Zelenina
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, RAS, Obrucheva Str. 40, Moscow 117342, Russia
| | - Natalia Kuzmenkova
- Radiochemistry Division, Faculty of Chemistry, Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russia
- V. Vernadsky Institute of Geochemistry and Analytical Chemistry, RAS, Kosygina Str. 19, Moscow 119991, Russia
| | - Denis Sobolev
- Nuclear Safety Institute, RAS, Bolshaya Tulskaya St. 52, Moscow 115191, Russia
| | - Kirill Boldyrev
- Nuclear Safety Institute, RAS, Bolshaya Tulskaya St. 52, Moscow 115191, Russia
| | - Zorigto Namsaraev
- Kurchatov Centre for Genome Research, NRC Kurchatov Institute, Akad. Kurchatov Sq., 2, Moscow 123098, Russia
| | - Grigoriy Artemiev
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, RAS, Obrucheva Str. 40, Moscow 117342, Russia
| | - Olga Samylina
- Winogradsky Institute of Microbiology, Research Centre for Biotechnology, Russian Academy of Sciences, Prospect 60-Letiya Oktyabrya 7/2, Moscow 117312, Russia
| | - Nadezhda Popova
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, RAS, Obrucheva Str. 40, Moscow 117342, Russia
| | - Alexey Safonov
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, RAS, Obrucheva Str. 40, Moscow 117342, Russia
- Correspondence:
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Manglass LM, Wintenberg M, Vogel C, Blenner M, Martinez NE. Accumulation of radio-iron and plutonium, alone and in combination, in Pseudomonas putidagrown in liquid cultures. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2021; 41:1199-1212. [PMID: 34644681 DOI: 10.1088/1361-6498/ac2f86] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 10/13/2021] [Indexed: 06/13/2023]
Abstract
The impact of low doses of ionising radiation on biological and environmental systems have been historically difficult to study. Modern biological tools have provided new methods for studying these mechanisms but applying these tools to a dose-response relationship may require refinement of dosimetric techniques that incorporate a detailed understand of radionuclide accumulation in biological cells, particularly when assessing the impact of low doses of ionising radiation. In this workPseudomonas putida (KT2440) grown in liquid culture was exposed to low dose rates (10-20 mGy d-1) of239Pu and55Fe, both alone and in combination, for a period of 20 days, and the accumulation of239Pu and55Fe in cell pellets was analysed via liquid scintillation counting. The study also considered of cells grown with239Pu and stable Fe (primarily56Fe). In addition to the analysis of cell pellet and media samples, this work includes analysis of the radiological content of ribonucleic acid extraction samples to examine uptake of radionuclides. Results indicate that239Pu inhibited the uptake of55Fe, and that the presence of stable and radioactive isotopes of Fe in cultures may promote pathways for Fe accumulation that are used by239Pu. The work herein provides foundational insight into future dosimetric models for our work with environmental bacteria.
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Affiliation(s)
- Lisa M Manglass
- Department of Environmental Engineering and Earth Science, Clemson University, Clemson, SC, United States of America
- Department of Physics and Engineering, Francis Marion University, Florence, SC, United States of America
| | - Molly Wintenberg
- Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, SC, United States of America
| | - Charlotte Vogel
- Department of Biological Sciences, Clemson University, Clemson, SC, United States of America
| | - Mark Blenner
- Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, SC, United States of America
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, United States of America
| | - Nicole E Martinez
- Department of Environmental Engineering and Earth Science, Clemson University, Clemson, SC, United States of America
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Manglass L, Wintenberg M, Blenner M, Martinez N. Pu-239 Accumulation in E. Coli and P. Putida Grown in Liquid Cultures. HEALTH PHYSICS 2021; 121:484-493. [PMID: 34392252 DOI: 10.1097/hp.0000000000001455] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
ABSTRACT Understanding of the behavior and effects of plutonium (Pu) in the environment is an important aspect of developing responsible and effective strategies for remediation and environmental stewardship. This work studies the sorption and uptake of 239Pu by common environmental bacteria, Escherichia coli DH10β and Pseudomonas putida KT-2440. Plutonium was directly incorporated into growth media prior to inoculation (0.12 kBq mL-1), and samples from the liquid cultures of E. coli and P. putida were analyzed over a 15-d growth period through liquid scintillation counting (LSC) of plutonium in cell pellets and cell culture media following centrifugation. To improve its solubility in the liquid cultures, Pu was complexed with citrate prior to inoculation. P. putida cultures were also grown without citrate to examine potential impact of P. putida's ability to use citrate as a food source. The accumulation of Pu in P. putida cells was found to increase both with and without citrate complexation for the first 5 d and then plateau until the end of the study period (15 d). A higher activity concentration of Pu was found in P. putida cells grown with citrate complexation than without. The activity concentration of plutonium in E. coli cells was greater than that in P. putida cells, which may be the result of a stronger complexing agent made by E. coli for the purpose of iron uptake. There are a variety of factors that influence Pu behavior in bacterial systems, and results confirm that even in a simple system, multiple mechanisms are at play.
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Affiliation(s)
| | - Molly Wintenberg
- Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, SC
| | - Mark Blenner
- Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, SC
| | - Nicole Martinez
- Center for Nuclear Environmental Engineering Sciences and Radioactive Waste Management (NEESRWM), Department of Environmental Engineering and Earth Sciences, Clemson University, Clemson, SC
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Février L, Coppin F, Pierrisnard S, Bourdillon M, Nguyen LV, Zaiter N, Brandès S, Sladkov V, Chambron JC, Meyer M. Efficiency of dihydroxamic and trihydroxamic siderochelates to extract uranium and plutonium from contaminated soils. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2021; 235-236:106645. [PMID: 34020181 DOI: 10.1016/j.jenvrad.2021.106645] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 04/30/2021] [Accepted: 05/05/2021] [Indexed: 05/29/2023]
Abstract
Actinide-based mineral phases occurring in contaminated soils can be solubilized by organic chelators excreted by plants, such as citrate. Herein, the efficiency of citrate towards U and Pu extraction is compared to that of siderophores, whose primary function is the acquisition of iron(III) as an essential nutrient and growth factor for many soil microorganisms. To that end, we selected desferrioxamine B (DFB) as an emblematic bacterial trishydroxamic siderophore and a synthetic analog, abbreviated (LCy,Pr)H2, of the tetradentate rhodotorulic acid (RA) produced by yeasts. Firstly, the uranyl speciation with both ligands was assessed in the pH range 2-11 by potentiometry and visible absorption spectrophotometry. Equilibrium constants and absorption spectra for three [UO2(DFB)Hh](h-1)+ (h = 1-3) and five [UO2(LCy,Pr)lHh](2+h-2l)+ (-1 ≤ h ≤ 1 for l = 1 and h = 0-1 for l = 2) solution complexes were determined at 25.0 °C and I = 0.1 M KNO3. Similar studies for the Fe3+/(LCy,Pr)2- system revealed the formation of five species having [Fe(LCy,Pr)]+, [Fe(LCy,Pr)OH], [Fe(LCy,Pr)(OH)2]-, [Fe(LCy,Pr)2H], and [Fe2(LCy,Pr)3] compositions. Then, the ability of DFB, (LCy,Pr)H2, and citrate to solubilize either U or Pu from pitchblende-rich soils (soils 1 and 2) or freshly plutonium-contaminated soils (LBS and PG) was evaluated by performing batch extraction tests. U was extracted significantly only by citrate after a day. After one week, the amount of U complexed by citrate only slightly exceeded that measured for the siderochelates, following the order citrate > (LCy,Pr)H2 ≥ DFB ≈ H2O, and were comparatively very low. Pu was also more efficiently extracted by citrate than by DFB after a day, but only by a factor of ~2-3 for the PG soil, while the Pu concentration in the supernatant after one week was approximately the same for both natural chelators. It remained nearly constant for DFB between the 1st and 7th day, but drastically decreased in the case of citrate, suggesting chemical decomposition in the latter case. For the Fe-rich soils 1 and 2, the efficiencies of the three chelators to solubilize Fe after a day were of the same order of magnitude, decreasing in the order DFB > citrate > (LCy,Pr)H2. However, after a week DFB had extracted ~1.5 times more Fe, whereas the amount extracted by the other chelators stayed constant. For the less Fe-rich LBS and PG soils contaminated by Pu, the amounts of extracted Fe were higher, especially after 7 days, and the DFB outperformed citrate by a factor of nearly 3. The higher capacity of the hexadentate DFB to extract Pu in the presence of Fe and its lower ability to mobilize U qualitatively agree with the respective complexation constant ratios, keeping in mind that both Pu-containing soils had a lower iron loading. Noticeably, (LCy,Pr)H2 has roughly the same capacity as DFB to solubilize U, but it mobilizes less Fe than the hexadentate siderophore. Similarly, citrate has the highest capacity to extract Pu, but the lowest to extract Fe. Therefore, compared to DFB, (LCy,Pr)H2 shows a better U/Fe extraction selectivity and citrate shows a better Pu/Fe selectivity.
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Affiliation(s)
- Laureline Février
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-ENV/SRTE/LR2T, BP 3, 13115, Saint-Paul-Lez-Durance Cedex, France.
| | - Frédéric Coppin
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-ENV/SRTE/LR2T, BP 3, 13115, Saint-Paul-Lez-Durance Cedex, France
| | - Sylvie Pierrisnard
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-ENV/SRTE/LR2T, BP 3, 13115, Saint-Paul-Lez-Durance Cedex, France
| | - Mélanie Bourdillon
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR 6302, CNRS, Université Bourgogne-Franche-Comté, 9 avenue Alain Savary, BP 47870, 21078, Dijon Cedex, France
| | - Lé Vi Nguyen
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR 6302, CNRS, Université Bourgogne-Franche-Comté, 9 avenue Alain Savary, BP 47870, 21078, Dijon Cedex, France
| | - Nissrine Zaiter
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR 6302, CNRS, Université Bourgogne-Franche-Comté, 9 avenue Alain Savary, BP 47870, 21078, Dijon Cedex, France
| | - Stéphane Brandès
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR 6302, CNRS, Université Bourgogne-Franche-Comté, 9 avenue Alain Savary, BP 47870, 21078, Dijon Cedex, France
| | - Vladimir Sladkov
- Laboratoire de Physique des 2 Infinis Irène Joliot Curie (IJCLab), UMR 9012, CNRS/IN2P3 Université Paris-Saclay, Université de Paris, 15 rue Georges Clemenceau, 91405, Orsay, France
| | - Jean-Claude Chambron
- Institut de Chimie de Strasbourg, UMR 7177, CNRS, Université de Strasbourg, 1 rue Blaise Pascal, BP 296 R 8, 67008, Strasbourg Cedex, France
| | - Michel Meyer
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), UMR 6302, CNRS, Université Bourgogne-Franche-Comté, 9 avenue Alain Savary, BP 47870, 21078, Dijon Cedex, France.
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Metal Reduction and Protein Secretion Genes Required for Iodate Reduction by Shewanella oneidensis. Appl Environ Microbiol 2019; 85:AEM.02115-18. [PMID: 30446562 DOI: 10.1128/aem.02115-18] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 11/07/2018] [Indexed: 01/28/2023] Open
Abstract
The metal-reducing gammaproteobacterium Shewanella oneidensis reduces iodate (IO3 -) as an anaerobic terminal electron acceptor. Microbial IO3 - electron transport pathways are postulated to terminate with nitrate (NO3 -) reductase, which reduces IO3 - as an alternative electron acceptor. Recent studies with S. oneidensis, however, have demonstrated that NO3 - reductase is not involved in IO3 - reduction. The main objective of the present study was to determine the metal reduction and protein secretion genes required for IO3 - reduction by Shewanella oneidensis with lactate, formate, or H2 as the electron donor. With all electron donors, the type I and type V protein secretion mutants retained wild-type IO3 - reduction activity, while the type II protein secretion mutant lacking the outer membrane secretin GspD was impaired in IO3 - reduction. Deletion mutants lacking the cyclic AMP receptor protein (CRP), cytochrome maturation permease CcmB, and inner membrane-tethered c-type cytochrome CymA were impaired in IO3 - reduction with all electron donors, while deletion mutants lacking c-type cytochrome MtrA and outer membrane β-barrel protein MtrB of the outer membrane MtrAB module were impaired in IO3 - reduction with only lactate as an electron donor. With all electron donors, mutants lacking the c-type cytochromes OmcA and MtrC of the metal-reducing extracellular electron conduit MtrCAB retained wild-type IO3 - reduction activity. These findings indicate that IO3 - reduction by S. oneidensis involves electron donor-dependent metal reduction and protein secretion pathway components, including the outer membrane MtrAB module and type II protein secretion of an unidentified IO3 - reductase to the S. oneidensis outer membrane.IMPORTANCE Microbial iodate (IO3 -) reduction is a major component in the biogeochemical cycling of iodine and the bioremediation of iodine-contaminated environments; however, the molecular mechanism of microbial IO3 - reduction is poorly understood. Results of the present study indicate that outer membrane (type II) protein secretion and metal reduction genes encoding the outer membrane MtrAB module of the extracellular electron conduit MtrCAB are required for IO3 - reduction by S. oneidensis On the other hand, the metal-reducing c-type cytochrome MtrC of the extracellular electron conduit is not required for IO3 - reduction by S. oneidensis These findings indicate that the IO3 - electron transport pathway terminates with an as yet unidentified IO3 - reductase that associates with the outer membrane MtrAB module to deliver electrons extracellularly to IO3.
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Ling J, Lu H, Wang Y, Johnson K, Wang S. One-dimensional chain structures of hexanuclear uranium(iv) clusters bridged by formate ligands. RSC Adv 2018; 8:34947-34953. [PMID: 35547079 PMCID: PMC9087207 DOI: 10.1039/c8ra06330c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 10/08/2018] [Indexed: 12/31/2022] Open
Abstract
Three one-dimensional chain structures of uranium(iv) hexanuclear clusters have been synthesized under hydrothermal/solvothermal conditions.
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Affiliation(s)
- Jie Ling
- Department of Chemistry and Biochemistry
- Claflin University
- Orangeburg
- USA
| | - Huangjie Lu
- State Key Laboratory of Radiation Medicine and Protection
- School for Radiological and Interdisciplinary Sciences
- Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institution
- Soochow University
- Suzhou
| | - Yaxing Wang
- State Key Laboratory of Radiation Medicine and Protection
- School for Radiological and Interdisciplinary Sciences
- Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institution
- Soochow University
- Suzhou
| | - Kenndra Johnson
- Department of Chemistry and Biochemistry
- Claflin University
- Orangeburg
- USA
| | - Shuao Wang
- State Key Laboratory of Radiation Medicine and Protection
- School for Radiological and Interdisciplinary Sciences
- Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institution
- Soochow University
- Suzhou
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10
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Moll H, Cherkouk A, Bok F, Bernhard G. Plutonium interaction studies with the Mont Terri Opalinus Clay isolate Sporomusa sp. MT-2.99: changes in the plutonium speciation by solvent extractions. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2017; 24:13497-13508. [PMID: 28390020 DOI: 10.1007/s11356-017-8969-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 03/30/2017] [Indexed: 06/07/2023]
Abstract
Since plutonium could be released from nuclear waste disposal sites, the exploration of the complex interaction processes between plutonium and bacteria is necessary for an improved understanding of the fate of plutonium in the vicinity of such a nuclear waste disposal site. In this basic study, the interaction of plutonium with cells of the bacterium, Sporomusa sp. MT-2.99, isolated from Mont Terri Opalinus Clay, was investigated anaerobically (in 0.1 M NaClO4) with or without adding Na-pyruvate as an electron donor. The cells displayed a strong pH-dependent affinity for Pu. In the absence of Na-pyruvate, a strong enrichment of stable Pu(V) in the supernatants was discovered, whereas Pu(IV) polymers dominated the Pu oxidation state distribution on the biomass at pH 6.1. A pH-dependent enrichment of the lower Pu oxidation states (e.g., Pu(III) at pH 6.1 which is considered to be more mobile than Pu(IV) formed at pH 4) was observed in the presence of up to 10 mM Na-pyruvate. In all cases, the presence of bacterial cells enhanced removal of Pu from solution and accelerated Pu interaction reactions, e.g., biosorption and bioreduction.
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Affiliation(s)
- Henry Moll
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Resource Ecology, Bautzner Landstrasse 400, 01328, Dresden, Germany.
| | - Andrea Cherkouk
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Resource Ecology, Bautzner Landstrasse 400, 01328, Dresden, Germany
| | - Frank Bok
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Resource Ecology, Bautzner Landstrasse 400, 01328, Dresden, Germany
| | - Gert Bernhard
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Resource Ecology, Bautzner Landstrasse 400, 01328, Dresden, Germany
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Interactions of Plutonium with Pseudomonas sp. Strain EPS-1W and Its Extracellular Polymeric Substances. Appl Environ Microbiol 2016; 82:7093-7101. [PMID: 27694230 DOI: 10.1128/aem.02572-16] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 09/23/2016] [Indexed: 11/20/2022] Open
Abstract
Safe and effective nuclear waste disposal, as well as accidental radionuclide releases, necessitates our understanding of the fate of radionuclides in the environment, including their interaction with microorganisms. We examined the sorption of Pu(IV) and Pu(V) to Pseudomonas sp. strain EPS-1W, an aerobic bacterium isolated from plutonium (Pu)-contaminated groundwater collected in the United States at the Nevada National Security Site (NNSS) in Nevada. We compared Pu sorption to cells with and without bound extracellular polymeric substances (EPS). Wild-type cells with intact EPS sorbed Pu(V) more effectively than cells with EPS removed. In contrast, cells with and without EPS showed the same sorption affinity for Pu(IV). In vitro experiments with extracted EPS revealed rapid reduction of Pu(V) to Pu(IV). Transmission electron microscopy indicated that 2- to 3-nm nanocrystalline Pu(IV)O2 formed on cells equilibrated with high concentrations of Pu(IV) but not Pu(V). Thus, EPS, while facilitating Pu(V) reduction, inhibit the formation of nanocrystalline Pu(IV) precipitates. IMPORTANCE Our results indicate that EPS are an effective reductant for Pu(V) and sorbent for Pu(IV) and may impact Pu redox cycling and mobility in the environment. Additionally, the resulting Pu morphology associated with EPS will depend on the concentration and initial Pu oxidation state. While our results are not directly applicable to the Pu transport situation at the NNSS, the results suggest that, in general, stationary microorganisms and biofilms will tend to limit the migration of Pu and provide an important Pu retardation mechanism in the environment. In a broader sense, our results, along with a growing body of literature, highlight the important role of microorganisms as producers of redox-active organic ligands and therefore as modulators of radionuclide redox transformations and complexation in the subsurface.
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Francis AJ, Dodge CJ. Microbial mobilization of plutonium and other actinides from contaminated soil. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2015; 150:277-285. [PMID: 26406590 DOI: 10.1016/j.jenvrad.2015.08.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 08/17/2015] [Accepted: 08/24/2015] [Indexed: 06/05/2023]
Abstract
We examined the dissolution of Pu, U, and Am in contaminated soil from the Nevada Test Site (NTS) due to indigenous microbial activity. Scanning transmission x-ray microscopy (STXM) analysis of the soil showed that Pu was present in its polymeric form and associated with Fe- and Mn- oxides and aluminosilicates. Uranium analysis by x-ray diffraction (μ-XRD) revealed discrete U-containing mineral phases, viz., schoepite, sharpite, and liebigite; synchrotron x-ray fluorescence (μ-XRF) mapping showed its association with Fe- and Ca-phases; and μ-x-ray absorption near edge structure (μ-XANES) confirmed U(IV) and U(VI) oxidation states. Addition of citric acid or glucose to the soil and incubated under aerobic or anaerobic conditions enhanced indigenous microbial activity and the dissolution of Pu. Detectable amount of Am and no U was observed in solution. In the citric acid-amended sample, Pu concentration increased with time and decreased to below detection levels when the citric acid was completely consumed. In contrast, with glucose amendment, Pu remained in solution. Pu speciation studies suggest that it exists in mixed oxidation states (III/IV) in a polymeric form as colloids. Although Pu(IV) is the most prevalent and generally considered to be more stable chemical form in the environment, our findings suggest that under the appropriate conditions, microbial activity could affect its solubility and long-term stability in contaminated environments.
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Affiliation(s)
- A J Francis
- Biological, Environmental & Climate Sciences Department, Brookhaven National Laboratory, Upton, NY 11973, USA.
| | - C J Dodge
- Biological, Environmental & Climate Sciences Department, Brookhaven National Laboratory, Upton, NY 11973, USA
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Xu C, Athon M, Ho YF, Chang HS, Zhang S, Kaplan DI, Schwehr KA, DiDonato N, Hatcher PG, Santschi PH. Plutonium immobilization and remobilization by soil mineral and organic matter in the far-field of the Savannah River Site, U.S. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:3186-3195. [PMID: 24555528 DOI: 10.1021/es404951y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
To study the effects of natural organic matter (NOM) on Pu sorption, Pu(IV) and (V) were amended at environmentally relevant concentrations (10(-14) M) to two soils of contrasting particulate NOM concentrations collected from the F-Area of the Savannah River Site. More Pu(IV) than (V) was bound to soil colloidal organic matter (COM). A de-ashed humic acid (i.e., metals being removed) scavenged more Pu(IV,V) into its colloidal fraction than the original HA incorporated into its colloidal fraction, and an inverse trend was thus observed for the particulate-fraction-bound Pu for these two types of HAs. However, the overall Pu binding capacity of HA (particulate + colloidal-Pu) decreased after de-ashing. The presence of NOM in the F-Area soil did not enhance Pu fixation to the organic-rich soil when compared to the organic-poor soil or the mineral phase from the same soil source, due to the formation of COM-bound Pu. Most importantly, Pu uptake by organic-rich soil decreased with increasing pH because more NOM in the colloidal size desorbed from the particulate fraction in the elevated pH systems, resulting in greater amounts of Pu associated with the COM fraction. This is in contrast to previous observations with low-NOM sediments or minerals, which showed increased Pu uptake with increasing pH levels. This demonstrates that despite Pu immobilization by NOM, COM can convert Pu into a more mobile form.
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Affiliation(s)
- Chen Xu
- Department of Marine Sciences, Texas A&M University , Building 3029, Galveston, Texas 77553, United States
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Abstract
The recent estimated global stockpile of separated plutonium (Pu) worldwide is about 500 t, with equal contributions from nuclear weapons and civilian nuclear energy. Independent of the United States' future nuclear energy policy, the current large and increasing stockpile of Pu needs to be safely isolated from the biosphere and stored for thousands of years. Recent laboratory and field studies have demonstrated the ability of colloids (1-1000 nm particles) to facilitate the migration of strongly sorbing contaminants such as Pu. In understanding the dominant processes that may facilitate the transport of Pu, the initial source chemistry and groundwater chemistry are important factors, as no one process can explain all the different field observations of Pu transport. Very little is known about the molecular-scale geochemical and biochemical mechanisms controlling Pu transport, leaving our conceptual model incomplete. Equally uncertain are the conditions that inhibit the cycling and mobility of Pu in the subsurface. Without a better mechanistic understanding for Pu at the molecular level, we cannot advance our ability to model its transport behavior and achieve confidence in predicting long-term transport. Without a conceptual model that can successfully predict long-term Pu behavior and ultimately isolation from the biosphere, the public will remain skeptical that nuclear energy is a viable and an attractive alternative to counter global warming effects of carbon-based energy alternatives. This review summarizes our current understanding of the relevant conditions and processes controlling the behavior of Pu in the environment, gaps in our scientific knowledge, and future research needs.
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Affiliation(s)
- Annie B Kersting
- Glenn T. Seaborg Institute, Physical & Life Sciences, Lawrence Livermore National Laboratory, L-231, P.O. Box 808, Livermore, California 94550, USA.
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16
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Walther C, Denecke MA. Actinide Colloids and Particles of Environmental Concern. Chem Rev 2013; 113:995-1015. [DOI: 10.1021/cr300343c] [Citation(s) in RCA: 119] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Clemens Walther
- Institute for Radioecology and
Radiation Protection, Leibniz University Hannover, Herrenhäuser Strasse 2, D-30419 Hannover, Germany
| | - Melissa A. Denecke
- Institute for Nuclear Waste
Disposal, Karlsruhe Institute of Technology, P.O. Box 3640, D-76021 Karlsruhe, Germany
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17
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Effect of microorganisms on the plutonium oxidation states. Appl Radiat Isot 2012; 70:442-9. [DOI: 10.1016/j.apradiso.2011.11.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Revised: 10/18/2011] [Accepted: 11/03/2011] [Indexed: 11/18/2022]
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Deo RP, Rittmann BE. A biogeochemical framework for bioremediation of plutonium(V) in the subsurface environment. Biodegradation 2012; 23:525-34. [DOI: 10.1007/s10532-011-9530-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2011] [Accepted: 12/17/2011] [Indexed: 11/24/2022]
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Harrington JM, Bargar JR, Jarzecki AA, Roberts JG, Sombers LA, Duckworth OW. Trace metal complexation by the triscatecholate siderophore protochelin: structure and stability. Biometals 2011; 25:393-412. [PMID: 22187125 DOI: 10.1007/s10534-011-9513-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Accepted: 12/01/2011] [Indexed: 11/29/2022]
Abstract
Although siderophores are generally viewed as biological iron uptake agents, recent evidence has shown that they may play significant roles in the biogeochemical cycling and biological uptake of other metals. One such siderophore that is produced by A. vinelandii is the triscatecholate protochelin. In this study, we probe the solution chemistry of protochelin and its complexes with environmentally relevant trace metals to better understand its effect on metal uptake and cycling. Protochelin exhibits low solubility below pH 7.5 and degrades gradually in solution. Electrochemical measurements of protochelin and metal-protochelin complexes reveal a ligand half-wave potential of 200 mV. The Fe(III)Proto(3-) complex exhibits a salicylate shift in coordination mode at circumneutral to acidic pH. Coordination of Mn(II) by protochelin above pH 8.0 promotes gradual air oxidation of the metal center to Mn(III), which accelerates at higher pH values. The Mn(III)Proto(3-) complex was found to have a stability constant of log β(110) = 41.6. Structural parameters derived from spectroscopic measurements and quantum mechanical calculations provide insights into the stability of the Fe(III)Proto(3-), Fe(III)H(3)Proto, and Mn(III)Proto(3-) complexes. Complexation of Co(II) by protochelin results in redox cycling of Co, accompanied by accelerated degradation of the ligand at all solution pH values. These results are discussed in terms of the role of catecholate siderophores in environmental trace metal cycling and intracellular metal release.
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Affiliation(s)
- James M Harrington
- Soil Science Department, North Carolina State University, Raleigh, NC 27695-7619, USA
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Kenney JPL, Fein JB. Cell wall reactivity of acidophilic and alkaliphilic bacteria determined by potentiometric titrations and Cd adsorption experiments. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2011; 45:4446-4452. [PMID: 21500771 DOI: 10.1021/es200191u] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In this study, we used potentiometric titrations and Cd adsorption experiments to determine the binding capacities of two acidophilic (A. cryptum and A. acidophilum) and two alkaliphilic (B. pseudofirmus and B. circulans) bacterial species in order to determine if any consistent trends could be observed relating bacterial growth environment to proton and Cd binding properties and to compare those binding behaviors to those of neutrophilic bacteria. All of the bacterial species studied exhibited significant proton buffering over the pH range in this study, with the alkaliphiles exhibiting significantly higher acidity constants than the acidophiles as well as the neutrophilic bacterial consortia. The calculated average site concentrations for each of the bacteria in this study are within 2σ experimental error of each other, with the exception of A. cryptum, which has a significantly higher Site 2 concentration than the other species. Despite differing acidity constants between the acidophiles and alkaliphiles, all bacteria except A. cryptum exhibited remarkably similar Cd adsorption behavior to each other, and the observed extent of adsorption was also similar to that predicted from a generalized model derived using neutrophilic bacterial consortia. This study demonstrates that bacteria that grow under extreme conditions exhibit similar proton and metal adsorption behavior to that of previously studied neutrophilic species and that a single set of proton and metal binding constants can be used to model the behavior of bacterial adsorption under a wide range of environmental conditions.
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Affiliation(s)
- Janice P L Kenney
- Department of Civil Engineering and Geological Sciences, University of Notre Dame, Notre Dame, Indiana 46556, USA.
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21
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Bacterial Pu(V) reduction in the absence and presence of Fe(III)–NTA: modeling and experimental approach. Biodegradation 2011; 22:921-9. [DOI: 10.1007/s10532-010-9451-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Accepted: 12/27/2010] [Indexed: 10/18/2022]
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O’Loughlin EJ, Boyanov MI, Antonopoulos DA, Kemner KM. Redox Processes Affecting the Speciation of Technetium, Uranium, Neptunium, and Plutonium in Aquatic and Terrestrial Environments. ACS SYMPOSIUM SERIES 2011. [DOI: 10.1021/bk-2011-1071.ch022] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Edward J. O’Loughlin
- Biosciences Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439
- The Institute for Genomics and Systems Biology, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439
| | - Maxim I. Boyanov
- Biosciences Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439
- The Institute for Genomics and Systems Biology, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439
| | - Dionysios A. Antonopoulos
- Biosciences Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439
- The Institute for Genomics and Systems Biology, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439
| | - Kenneth M. Kemner
- Biosciences Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439
- The Institute for Genomics and Systems Biology, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439
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Marshall MJ, Beliaev AS, Fredrickson JK. Microbial Transformations of Radionuclides in the Subsurface. Environ Microbiol 2010. [DOI: 10.1002/9780470495117.ch4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Xu C, Santschi PH, Schwehr KA, Hung CC. Optimized isolation procedure for obtaining strongly actinide binding exopolymeric substances (EPS) from two bacteria (Sagittula stellata and Pseudomonas fluorescens Biovar II). BIORESOURCE TECHNOLOGY 2009; 100:6010-6021. [PMID: 19574036 DOI: 10.1016/j.biortech.2009.06.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2008] [Revised: 09/09/2008] [Accepted: 06/02/2009] [Indexed: 05/28/2023]
Abstract
Different chemical extractants (NaCl, EDTA, HCl and NaOH) and physical methods (ultrasonication and heating) were examined by their efficacies of extracting "attached" exopolymeric substances (EPS) secreted by marine bacterium Sagittula stellata (SS) and terrestrial bacterium Pseudomonas fluorescens Biovar II (PF). Extraction by 0.5 N HCl for 3 h was best for SS while extraction by 0.05 N NaCl for 3-5 h was regarded as optimal for PF. Improvements in EPS purification included a pre-diafiltration step to remove the broth material and reduce the solution volume, thus the usage of ethanol, and time. The EPS harvested at the optimal time and purified by the improved method were enriched in polysaccharides, with smaller amounts of proteins, thus having amphiphilic properties. Isoelectric focusing of (234)Th or (240)Pu labeled EPS showed both actinides were strongly bound to macromolecules with low pI, similar to reported marine or soil colloidal natural organic matter (NOM).
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Affiliation(s)
- Chen Xu
- Laboratory for Oceanographic and Environmental Research, Departments of Oceanography and Marine Sciences, Texas A&M University, 5007 Avenue U, Galveston, TX 77551, United States.
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Takao S, Takao K, Kraus W, Emmerling F, Scheinost AC, Bernhard G, Hennig C. First Hexanuclear UIVand ThIVFormate Complexes - Structure and Stability Range in Aqueous Solution. Eur J Inorg Chem 2009. [DOI: 10.1002/ejic.200900899] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Moll H, Merroun M, Hennig C, Rossberg A, Selenska-Pobell S, Bernhard G. The interaction ofDesulfovibrio äspöensisDSM 10631Twith plutonium. RADIOCHIM ACTA 2009. [DOI: 10.1524/ract.2006.94.12.815] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Microbes are widely distributed in nature and they can strongly influence the migration of actinides in the environment. This investigation describes the interaction of plutonium in mixed oxidation states (Pu(VI) and Pu(IV)-polymers) with cells of the sulfate-reducing bacterial (SRB) strainDesulfovibrio äspöensisDSM 10631T, which frequently occurs in the deep granitic rock aquifers at the Äspö Hard Rock Laboratory (Äspö HRL), Sweden. In this study, accumulation experiments were performed in order to obtain information about the amount of Pu bound by the bacteria in dependence on the contact time and the initial plutonium concentration. We used solvent extractions, UV-Vis absorption spectroscopy and X-ray absorption near edge structure (XANES) spectroscopy to determine the speciation of Pu oxidation states. Extended X-ray absorption fine structure (EXAFS) spectroscopy was used to study the coordination of the Pu bound by the bacteria. In the first step, the Pu(VI) and Pu(IV)-polymers are bound to the biomass. Solvent extractions showed that 97% of the initially present Pu(VI) is reduced to Pu(V) due to the activity of the cells within the first 24 h of contact time. Most of the formed Pu(V) dissolves from the cell envelope back to the aqueous solution due to the weak complexing properties of this plutonium oxidation state. Indications were found for a penetration of Pu species inside the bacterial cells.
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Crumbliss AL, Harrington JM. Iron sequestration by small molecules: Thermodynamic and kinetic studies of natural siderophores and synthetic model compounds. ADVANCES IN INORGANIC CHEMISTRY 2009. [DOI: 10.1016/s0898-8838(09)00204-9] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Francis AJ, Dodge CJ, Gillow JB. Reductive dissolution of Pu(IV) by Clostridium sp. under anaerobic conditions. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2008; 42:2355-2360. [PMID: 18504965 DOI: 10.1021/es072016w] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
An anaerobic, gram positive, spore-forming bacterium Clostridium sp., common in soils and wastes, capable of reduction of Fe(III) to Fe(II), Mn(IV) to Mn(II), Tc(VII) to Tc(IV), and U(VI) to U(IV), reduced Pu(IV) to Pu(III). Addition of 242Pu (IV)-nitrate to the bacterial growth medium at pH 6.4 resulted in the precipitation of Pu as amorphous Pu(OH)4 due to hydrolysis and polymerization reactions. The Pu (1 x 10(-5) M) had no effect upon growth of the bacterium as evidenced by glucose consumption; carbon dioxide and hydrogen production; a decrease in pH of the medium from 6.4 to 3.0 due to production of acetic and butyric acids from glucose fermentation; and a change in the Eh of the culture medium from +50 to -180 mV. Commensurate with bacterial growth, Pu was rapidly solubilized as evidenced by an increase in Pu concentration in solution which passed through a 0.03 microm filtration. Selective solvent extraction of the culture by thenoyltrifluoroacetone (TTA) indicated the presence of a reduced Pu species in the soluble fraction. X-ray absorption near edge spectroscopic (XANES) analysis of Pu in the culture sample at the Pu LIII absorption edge (18.054 keV) showed a shift of -3 eV compared to a Pu(IV) standard indicating reduction of Pu(IV) to Pu(III). These results suggestthat, although Pu generally exists as insoluble Pu(IV) in the environment, under appropriate conditions, anaerobic microbial activity could affect the long-term stability and mobility of Pu by its reductive dissolution.
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Affiliation(s)
- Arokiasamy J Francis
- Environmental Sciences Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
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Thermodynamic studies of actinide complexes. 1. A reappraisal of the solution equilibria between plutonium(IV) and ethylenediaminetetraacetic acid (EDTAH4) in nitric media. CR CHIM 2007. [DOI: 10.1016/j.crci.2007.04.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Renshaw JC, Lloyd JR, Livens FR. Microbial interactions with actinides and long-lived fission products. CR CHIM 2007. [DOI: 10.1016/j.crci.2007.02.013] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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