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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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Daronnat L, Holfeltz V, Boubals N, Dumas T, Guilbaud P, Martinez DM, Moisy P, Sauge-Merle S, Lemaire D, Solari PL, Berthon L, Berthomieu C. Investigation of the Plutonium(IV) Interactions with Two Variants of the EF-Hand Ca-Binding Site I of Calmodulin. Inorg Chem 2023; 62:8334-8346. [PMID: 37184364 DOI: 10.1021/acs.inorgchem.3c00845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Due to its presence in the nuclear industry and its strong radiotoxicity, plutonium is an actinide of major interest in the event of internal contamination. To improve the understanding of its mechanisms of transport and accumulation in the body, the complexation of Pu(IV) to the most common protein calcium-binding motif found in cells, the EF-hand motif of calmodulin, was investigated. Visible and X-ray absorption spectroscopies (XAS) in solution made it possible to investigate the speciation of plutonium at physiological pH (pH 7.4) and pH 6 in two variants of the calmodulin Ca-binding site I and using Pu(IV) in different media: carbonate, chloride, or nitrate solutions. Three different species of Pu were identified in the samples, with formation of 1:1 Pu(IV):calmodulin peptide complexes, Pu(IV) reduction, and formation of peptide-mediated Pu(IV) hexanuclear cluster.
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Affiliation(s)
- Loïc Daronnat
- CEA, DES, ISEC, DMRC, Univ Montpellier, Marcoule, Bagnols-sur-cèze 30200, France
| | - Vanessa Holfeltz
- CEA, DES, ISEC, DMRC, Univ Montpellier, Marcoule, Bagnols-sur-cèze 30200, France
| | - Nathalie Boubals
- CEA, DES, ISEC, DMRC, Univ Montpellier, Marcoule, Bagnols-sur-cèze 30200, France
| | - Thomas Dumas
- CEA, DES, ISEC, DMRC, Univ Montpellier, Marcoule, Bagnols-sur-cèze 30200, France
| | - Philippe Guilbaud
- CEA, DES, ISEC, DMRC, Univ Montpellier, Marcoule, Bagnols-sur-cèze 30200, France
| | | | - Philippe Moisy
- CEA, DES, ISEC, DMRC, Univ Montpellier, Marcoule, Bagnols-sur-cèze 30200, France
| | - Sandrine Sauge-Merle
- Aix Marseille Université, CEA, CNRS, BIAM, UMR7265, IPM, Saint Paul-Lez-Durance 13108, France
| | - David Lemaire
- Aix Marseille Université, CEA, CNRS, BIAM, UMR7265, IPM, Saint Paul-Lez-Durance 13108, France
| | - Pier Lorenzo Solari
- Synchrotron SOLEIL, L'Orme des Merisiers, Départementale 128, Saint Aubin 91190, France
| | - Laurence Berthon
- CEA, DES, ISEC, DMRC, Univ Montpellier, Marcoule, Bagnols-sur-cèze 30200, France
| | - Catherine Berthomieu
- Aix Marseille Université, CEA, CNRS, BIAM, UMR7265, IPM, Saint Paul-Lez-Durance 13108, France
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Balboni E, Merino N, Begg JD, Samperton KM, Zengotita FE, Law GTW, Kersting AB, Zavarin M. Plutonium mobilization from contaminated estuarine sediments, Esk Estuary (UK). CHEMOSPHERE 2022; 308:136240. [PMID: 36057346 DOI: 10.1016/j.chemosphere.2022.136240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 08/24/2022] [Accepted: 08/25/2022] [Indexed: 06/15/2023]
Abstract
Since 1952, liquid radioactive effluent containing238-242Pu, 241Am, 237Np, 137Cs, and 99Tc has been released with authorization from the Sellafield nuclear complex (UK) into the Irish Sea. This represents the largest source of plutonium (Pu) discharged in all western Europe, with 276 kg having been released. In the Eastern Irish Sea, the majority of the transuranic activity has settled into an area of sediments (Mudpatch) located off the Cumbrian coast. Radionuclides from the Mudpatch have been re-dispersed via particulate transport in fine-grained estuarine and intertidal sediments to the North-East Irish Sea, including the intertidal saltmarsh located at the mouth of the Esk Estuary. Saltmarshes are highly dynamic systems which are vulnerable to external agents (sea level change, erosion, sediment supply, and freshwater inputs), and their stability remains uncertain under current sea level rise projections and possible increases in storm activity. In this work, we examined factors affecting Pu mobility in contaminated sediments collected from the Esk Estuary by conducting leaching experiments under both anoxic and oxic conditions. Leaching experiments were conducted over a 9-month period and were periodically sampled to determine solution phase Pu via multicollector-inductively coupled plasma-mass spectrometry (MC-ICP-MS), and to measure redox indicators (Eh, pH and extractable Fe(II)). Microbial community composition was also characterized in the sediments, and at the beginning and end of the anoxic/oxic experiments. Results show that: 1) Pu leaching is about three times greater in solutions leached under anoxic conditions compared to oxic conditions, 2) the sediment slurry microbial communities shift as conditions change from anoxic to oxic, 3) Pu leaching is enhanced in the shallow sediments (0-10 cm depth), and 4) the magnitude of Pu leached from sediments is not correlated with total Pu, indicating that the biogeochemistry of sediment-associated Pu is spatially heterogeneous. These findings provide constraints on the stability of redox sensitive Pu in biogeochemically dynamic/transient environments on a timescale of months and suggests that anoxic conditions can enhance Pu mobility in estuarine systems.
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Affiliation(s)
- Enrica Balboni
- Seaborg Institute, Lawrence Livermore National Laboratory, Livermore, CA, 94550, United States.
| | - Nancy Merino
- Seaborg Institute, Lawrence Livermore National Laboratory, Livermore, CA, 94550, United States
| | - James D Begg
- Seaborg Institute, Lawrence Livermore National Laboratory, Livermore, CA, 94550, United States; Amphos 21, Barcelona, Spain
| | - Kyle M Samperton
- Seaborg Institute, Lawrence Livermore National Laboratory, Livermore, CA, 94550, United States; Trace Nuclear Measurement Technology Group, Savannah River National Laboratory, Aiken, SC, 29808, United States
| | - Frances E Zengotita
- Seaborg Institute, Lawrence Livermore National Laboratory, Livermore, CA, 94550, United States; Department of Civil & Environmental Engineering & Earth Sciences, University of Notre Dame, Notre Dame, IN, 46556, United States
| | - Gareth T W Law
- Radiochemistry Unit, Department of Chemistry, University of Helsinki, Finland
| | - Annie B Kersting
- Seaborg Institute, Lawrence Livermore National Laboratory, Livermore, CA, 94550, United States
| | - Mavrik Zavarin
- Seaborg Institute, Lawrence Livermore National Laboratory, Livermore, CA, 94550, United States
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Insights into the Biosynthesis of Nanoparticles by the Genus Shewanella. Appl Environ Microbiol 2021; 87:e0139021. [PMID: 34495739 DOI: 10.1128/aem.01390-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The exploitation of microorganisms for the fabrication of nanoparticles (NPs) has garnered considerable research interest globally. The microbiological transformation of metals and metal salts into respective NPs can be achieved under environmentally benign conditions, offering a more sustainable alternative to chemical synthesis methods. Species of the metal-reducing bacterial genus Shewanella are able to couple the oxidation of various electron donors, including lactate, pyruvate, and hydrogen, to the reduction of a wide range of metal species, resulting in biomineralization of a multitude of metal NPs. Single-metal-based NPs as well as composite materials with properties equivalent or even superior to physically and chemically produced NPs have been synthesized by a number of Shewanella species. A mechanistic understanding of electron transfer-mediated bioreduction of metals into respective NPs by Shewanella is crucial in maximizing NP yields and directing the synthesis to produce fine-tuned NPs with tailored properties. In addition, thorough investigations into the influence of process parameters controlling the biosynthesis is another focal point for optimizing the process of NP generation. Synthesis of metal-based NPs using Shewanella species offers a low-cost, eco-friendly alternative to current physiochemical methods. This article aims to shed light on the contribution of Shewanella as a model organism in the biosynthesis of a variety of NPs and critically reviews the current state of knowledge on factors controlling their synthesis, characterization, potential applications in different sectors, and future prospects.
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Schramke J, Santillan E, Peake R. Plutonium Oxidation States in the Waste Isolation Pilot Plant Repository. APPLIED GEOCHEMISTRY : JOURNAL OF THE INTERNATIONAL ASSOCIATION OF GEOCHEMISTRY AND COSMOCHEMISTRY 2020; 116:10.1016/j.apgeochem.2020.104561. [PMID: 32489229 PMCID: PMC7266098 DOI: 10.1016/j.apgeochem.2020.104561] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The Waste Isolation Pilot Plant (WIPP), a deep geologic repository located 660 meters underground in bedded salt, is designed to isolate U.S. defense-related transuranic waste from the accessible environment. Plutonium isotopes are the most important radionuclides in WIPP waste. Plutonium solubility in WIPP brines (ionic strengths from 5.3 to 7.4) is strongly dependent on its oxidation state, with much lower solubilities associated with Pu(III) and Pu(IV) than with the higher Pu(V) and Pu(VI) oxidation states. The large quantity of metallic iron in WIPP waste and waste containers is expected to undergo anoxic corrosion, producing strongly reducing conditions and high hydrogen gas pressures after repository closure and brine intrusion. Because reducing conditions will prevail in the WIPP repository, the most important long-term oxidation states will be Pu(III) and Pu(IV). We performed a literature review to evaluate the effects of WIPP chemical and physical processes (not colloidal) on plutonium oxidation states that included reactions with reducing agents such as iron solids and aqueous species and radiolysis of solids and aqueous species. The results of this review indicate that equilibrium between Pu(III) solids and aqueous species will control dissolved plutonium concentrations in WIPP brines. We also performed geochemical modeling calculations using the ThermoChimie database to support this assessment of plutonium oxidation states in the long-term WIPP repository. Control of plutonium solubilities by Pu(III) solid instead of Pu(IV) solid may lead to higher predicted plutonium concentrations in brines potentially released to the ground surface by an inadvertent drilling intrusion into the long-term WIPP repository. The results of this study demonstrate that Pu(III) solid solubilities provide a reasonable upper bound for dissolved plutonium concentrations in WIPP brines.
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Affiliation(s)
- J.A. Schramke
- SC&A Inc., 2200 Wilson Blvd, Suite 300, Arlington, Virginia 22201
| | - E.F.U. Santillan
- U.S. Environmental Protection Agency, Office of Air and Radiation
| | - R.T. Peake
- U.S. Environmental Protection Agency, Office of Air and Radiation
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Multilocus Sequence Analysis, a Rapid and Accurate Tool for Taxonomic Classification, Evolutionary Relationship Determination, and Population Biology Studies of the Genus Shewanella. Appl Environ Microbiol 2019; 85:AEM.03126-18. [PMID: 30902862 DOI: 10.1128/aem.03126-18] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 03/19/2019] [Indexed: 02/02/2023] Open
Abstract
The genus Shewanella comprises a group of marine-dwelling species with worldwide distribution. Several species are regarded as causative agents of food spoilage and opportunistic pathogens of human diseases. In this study, a standard multilocus sequence analysis (MLSA) based on six protein-coding genes (gyrA, gyrB, infB, recN, rpoA, and topA) was established as a rapid and accurate identification tool in 59 Shewanella type strains. This method yielded sufficient resolving power in regard to enough informative sites, adequate sequence divergences, and distinct interspecies branches. The stability of phylogenetic topology was supported by high bootstrap values and concordance with different methods. The reliability of the MLSA scheme was further validated by identical phylogenies and high correlations of genomes. The MLSA approach provided a robust system to exhibit evolutionary relationships in the Shewanella genus. The split network tree proposed twelve distinct monophyletic clades with identical G+C contents and high genetic similarities. A total of 86 tested strains were investigated to explore the population biology of the Shewanella genus in China. The most prevalent Shewanella species was Shewanella algae, followed by Shewanella xiamenensis, Shewanella chilikensis, Shewanella indica, Shewanella seohaensis, and Shewanella carassii The strains frequently isolated from clinical and food samples highlighted the importance of increasing the surveillance of Shewanella species. Based on the combined genetic, genomic, and phenotypic analyses, Shewanella upenei should be considered a synonym of S. algae, and Shewanella pacifica should be reclassified as a synonym of Shewanella japonica IMPORTANCE The MLSA scheme based on six housekeeping genes (HKGs) (gyrA, gyrB, infB, recN, rpoA, and topA) is well established as a reliable tool for taxonomic, evolutionary, and population diversity analyses of the genus Shewanella in this study. The standard MLSA method allows researchers to make rapid, economical, and precise identification of Shewanella strains. The robust phylogenetic network of MLSA provides profound insight into the evolutionary structure of the genus Shewanella The population genetics of Shewanella species determined by the MLSA approach plays a pivotal role in clinical diagnosis and routine monitoring. Further studies on remaining species and genomic analysis will enhance a more comprehensive understanding of the microbial systematics, phylogenetic relationships, and ecological status of the genus Shewanella.
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Safonov AV, Andryushchenko ND, Ivanov PV, Boldyrev KA, Babich TL, German KE, Zakharova EV. Biogenic Factors of Radionuclide Immobilization on Sandy Rocks of Upper Aquifers. RADIOCHEMISTRY 2019. [DOI: 10.1134/s1066362219010156] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Al-Qasmi H, Law GTW, Fifield LK, Howe JA, Brand T, Cowie GL, Law KA, Livens FR. Deposition of artificial radionuclides in sediments of Loch Etive, Scotland. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2018; 187:45-52. [PMID: 29429873 DOI: 10.1016/j.jenvrad.2018.02.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 10/08/2017] [Accepted: 02/01/2018] [Indexed: 06/08/2023]
Abstract
The nuclear fuel reprocessing plants on the Sellafield site (UK) have released low-level effluents into the Irish Sea under authorisation since 1952. This has led to the labelling of nearby offshore sediments with a range of artificial radionuclides. In turn, these sediments act as a long-term secondary source of both soluble and particle-associated radionuclides to coastal areas. These radionuclides are of interest both in assessing possible environmental impacts and as tracers for marine processes. Here we present results from a study of the geochemistry of natural (234, 238U) and artificial (137Cs, 241Am, 238Pu, 239+240Pu, and 236U) radionuclides and their accumulation in sediments from Loch Etive, Scotland. The data are interpreted in the context of the historical radioactive discharges to the Irish Sea and biogeochemical processes in marine sediments. Loch Etive is divided into two basins; a lower, seaward basin where the sedimentation rate (∼0.6 cm/yr) is about twice that of the more isolated upper basin (∼0.3 cm/yr). These accumulation rates are consistent with the broad distribution of 137Cs in the sediment profiles which can be related to the maximum Sellafield discharges of 137Cs in the mid-1970s and suggest that 137Cs was mainly transported in solution to Loch Etive during that period. Enrichments of Mn, Fe, and Mo in sediment and porewater from both Loch Etive basins result from contemporary biogeochemical redox processes. Enrichments of 238U and 234U in the lower basin may be a result of the cycling of natural U. By contrast, the Sellafield-derived artificial isotope 236U does not seem to be affected by the redox-driven reactions in the lower basin. The 238Pu/239,240Pu ratios suggest contributions from both historical Sellafield discharges and global fallout Pu. The uniform sediment distributions of Pu and Am, which do not reflect Sellafield historical discharges, suggest the existence of a homogenous secondary source. This could be the offshore 'mud patch' in the vicinity of Sellafield from which the supply of radionuclides reflects time-integrated Sellafield discharges. This source could also account for the continuing supply of Cs to Loch Etive, even after substantial reductions in discharge from the Sellafield site.
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Affiliation(s)
- Hamza Al-Qasmi
- Centre for Radiochemistry Research, School of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Gareth T W Law
- Centre for Radiochemistry Research, School of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - L Keith Fifield
- Department of Nuclear Physics, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200, Australia
| | - John A Howe
- Scottish Association for Marine Science, Oban, Argyll, PA37 1QA, UK
| | - Tim Brand
- Scottish Association for Marine Science, Oban, Argyll, PA37 1QA, UK
| | - Gregory L Cowie
- School of Geosciences, The University of Edinburgh, King's Buildings, Edinburgh, EH9 3FE, UK
| | - Kathleen A Law
- Centre for Radiochemistry Research, School of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Francis R Livens
- Centre for Radiochemistry Research, School of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
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Xie J, Liang W, Lin J, Zhou X, Li M. Humic acids facilitated microbial reduction of polymeric Pu(IV) under anaerobic conditions. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 610-611:1321-1328. [PMID: 28851152 DOI: 10.1016/j.scitotenv.2017.08.184] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2017] [Revised: 07/26/2017] [Accepted: 08/17/2017] [Indexed: 06/07/2023]
Abstract
Flavins and humic substances have been extensively studied with emphasis on their ability to transfer extracellular electrons to insoluble metal oxides. Nevertheless, whether the low-solubility Pu(IV) polymers are microbially reduced to aqueous Pu(III) remains uncertain. Experiments were conducted under anaerobic and slightly alkaline conditions to study the difference between humic acids and flavins to transport extracellular electrons to Pu(IV) polymers. Our study demonstrates that Shewanella putrefaciens was unable to directly reduce polymeric Pu(IV) with a notably low reduction rate (3.4×10-12mol/L Pu(III)aq within 144h). The relatively high redox potential of flavins reveals the thermodynamically unfavorable reduction: Eh(PuO2(am)/Pu3+)<Eho'(FMN/FMNH2)≈Eho'(RBF/RBFH2)≈-220mV at pH7.2. The microbially reduced humic acids facilitated the extracellular electron transfer to the polymers and reduced polymeric Pu(IV) (2.1×10-10mol/L Pu(III)aq) 62 times more rapidly than the flavins. The driving force for electron transfer explains the observed reduction: Eh(HAox/HAred)<Eh(PuO2(am)/Pu3+) when S. putrefaciens oxidized lactate and respired on the humic acids. In contrast, flavins were able to substantially reduce aqueous Pu(IV)-EDTA (1.9×10-9mol/L Pu(III)aq) because of the available driving force for electron transfer: ΔrGm=-F[Eh(PuL24-/PuL25-)-Eho'(FMN/FMNH2)]=-33.5kJ/mol is a result of Eh(PuL24-/PuL25-)≫Eh(PuO2(am)/Pu3+), where L is the EDTA ligand. In the presence of humic acids, the reduction of Pu(IV)-EDTA exhibited the most rapid rate (2.2×10-9mol/L Pu(III)aq). This result further demonstrates that humic acids facilitated the extracellular electron transfer to polymeric and aqueous Pu(IV). Reductive solubilization of the polymers may enhance Pu mobility in the geosphere and hence increases risks to human health.
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Affiliation(s)
- Jinchuan Xie
- Northwest Institute of Nuclear Technology, P.O. Box 69-14, Xi'an City, Shanxi Province 710024, PR China.
| | - Wei Liang
- Northwest Institute of Nuclear Technology, P.O. Box 69-14, Xi'an City, Shanxi Province 710024, PR China
| | - Jianfeng Lin
- Northwest Institute of Nuclear Technology, P.O. Box 69-14, Xi'an City, Shanxi Province 710024, PR China
| | - Xiaohua Zhou
- Northwest Institute of Nuclear Technology, P.O. Box 69-14, Xi'an City, Shanxi Province 710024, PR China
| | - Mei Li
- Northwest Institute of Nuclear Technology, P.O. Box 69-14, Xi'an City, Shanxi Province 710024, PR China
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Xie J, Han X, Wang W, Zhou X, Lin J. Effects of humic acid concentration on the microbially-mediated reductive solubilization of Pu(IV) polymers. JOURNAL OF HAZARDOUS MATERIALS 2017; 339:347-353. [PMID: 28668752 DOI: 10.1016/j.jhazmat.2017.06.054] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 04/03/2017] [Accepted: 06/21/2017] [Indexed: 06/07/2023]
Abstract
The role of humic acid concentration in the microbially-mediated reductive solubilization of Pu(IV) polymers remains unclear until now. The effects of humic concentration (0-150.5mg/L) on the rate and extent of reduction of polymeric Pu(IV) were studied under anaerobic and pH 7.2 conditions. The results show that Shewanella putrefaciens, secreting flavins as endogenous electron shuttles, cannot notably stimulate the reduction of polymeric Pu(IV). In the presence of humic acids, the reduction rate of polymeric Pu(IV) increased with increasing humic concentrations (0-15.0mg/L): e.g., a 102-fold increase from 4.1×10-15 (HA=0) to 4.2×10-13mol Pu(III)aq/h (HA=15.0mg/L). The bioreduced humic acids by S. putrefaciens facilitated the extracellular electron transfer to Pu(IV) polymers and thus the reduction of polymeric Pu(IV) to Pu(III)aq became thermodynamically favorable. However, the reduction rate did not increase but decrease with increasing humic concentrations from 15.0 to 150.5mg/L. Humic coatings formed on the polymer surfaces at relatively high humic concentrations limited the electron transfer to the polymers and thus decreased the reduction rate. The finding of the dynamic role of humic acids in the bioreductive solubilization may be helpful in evaluating Pu mobility in the geosphere.
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Affiliation(s)
- Jinchuan Xie
- Northwest Institute of Nuclear Technology, P. O. Box 69-14, Xi'an City, Shanxi Province 710024, PR China.
| | - Xiaoyuan Han
- Northwest Institute of Nuclear Technology, P. O. Box 69-14, Xi'an City, Shanxi Province 710024, PR China
| | - Weixian Wang
- Northwest Institute of Nuclear Technology, P. O. Box 69-14, Xi'an City, Shanxi Province 710024, PR China
| | - Xiaohua Zhou
- Northwest Institute of Nuclear Technology, P. O. Box 69-14, Xi'an City, Shanxi Province 710024, PR China
| | - Jianfeng Lin
- Northwest Institute of Nuclear Technology, P. O. Box 69-14, Xi'an City, Shanxi Province 710024, PR China
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Harding T, Roger AJ, Simpson AGB. Adaptations to High Salt in a Halophilic Protist: Differential Expression and Gene Acquisitions through Duplications and Gene Transfers. Front Microbiol 2017; 8:944. [PMID: 28611746 PMCID: PMC5447177 DOI: 10.3389/fmicb.2017.00944] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 05/11/2017] [Indexed: 11/13/2022] Open
Abstract
The capacity of halophiles to thrive in extreme hypersaline habitats derives partly from the tight regulation of ion homeostasis, the salt-dependent adjustment of plasma membrane fluidity, and the increased capability to manage oxidative stress. Halophilic bacteria, and archaea have been intensively studied, and substantial research has been conducted on halophilic fungi, and the green alga Dunaliella. By contrast, there have been very few investigations of halophiles that are phagotrophic protists, i.e., protozoa. To gather fundamental knowledge about salt adaptation in these organisms, we studied the transcriptome-level response of Halocafeteria seosinensis (Stramenopiles) grown under contrasting salinities. We provided further evolutionary context to our analysis by identifying genes that underwent recent duplications. Genes that were highly responsive to salinity variations were involved in stress response (e.g., chaperones), ion homeostasis (e.g., Na+/H+ transporter), metabolism and transport of lipids (e.g., sterol biosynthetic genes), carbohydrate metabolism (e.g., glycosidases), and signal transduction pathways (e.g., transcription factors). A significantly high proportion (43%) of duplicated genes were also differentially expressed, accentuating the importance of gene expansion in adaptation by H. seosinensis to high salt environments. Furthermore, we found two genes that were lateral acquisitions from bacteria, and were also highly up-regulated and highly expressed at high salt, suggesting that this evolutionary mechanism could also have facilitated adaptation to high salt. We propose that a transition toward high-salt adaptation in the ancestors of H. seosinensis required the acquisition of new genes via duplication, and some lateral gene transfers (LGTs), as well as the alteration of transcriptional programs, leading to increased stress resistance, proper establishment of ion gradients, and modification of cell structure properties like membrane fluidity.
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Affiliation(s)
- Tommy Harding
- Department of Biochemistry and Molecular Biology, Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie UniversityHalifax, NS, Canada
| | - Andrew J. Roger
- Department of Biochemistry and Molecular Biology, Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie UniversityHalifax, NS, Canada
| | - Alastair G. B. Simpson
- Department of Biology and Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie UniversityHalifax, NS, Canada
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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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Cherkouk A, Law GTW, Rizoulis A, Law K, Renshaw JC, Morris K, Livens FR, Lloyd JR. Influence of riboflavin on the reduction of radionuclides by Shewanella oneidenis MR-1. Dalton Trans 2016; 45:5030-7. [PMID: 26632613 DOI: 10.1039/c4dt02929a] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Uranium (as UO2(2+)), technetium (as TcO4(-)) and neptunium (as NpO2(+)) are highly mobile radionuclides that can be reduced enzymatically by a range of anaerobic and facultatively anaerobic microorganisms, including Shewanella oneidensis MR-1, to poorly soluble species. The redox chemistry of Pu is more complicated, but the dominant oxidation state in most environments is highly insoluble Pu(IV), which can be reduced to Pu(III) which has a potentially increased solubility which could enhance migration of Pu in the environment. Recently it was shown that flavins (riboflavin and flavin mononucleotide (FMN)) secreted by Shewanella oneidensis MR-1 can act as electron shuttles, promoting anoxic growth coupled to the accelerated reduction of poorly-crystalline Fe(III) oxides. Here, we studied the role of riboflavin in mediating the reduction of radionuclides in cultures of Shewanella oneidensis MR-1. Our results demonstrate that the addition of 10 μM riboflavin enhances the reduction rate of Tc(VII) to Tc(IV), Pu(IV) to Pu(III) and to a lesser extent, Np(V) to Np(IV), but has no significant influence on the reduction rate of U(VI) by Shewanella oneidensis MR-1. Thus riboflavin can act as an extracellular electron shuttle to enhance rates of Tc(VII), Np(V) and Pu(IV) reduction, and may therefore play a role in controlling the oxidation state of key redox active actinides and fission products in natural and engineered environments. These results also suggest that the addition of riboflavin could be used to accelerate the bioremediation of radionuclide-contaminated environments.
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Affiliation(s)
- Andrea Cherkouk
- Research Centre for Radwaste Disposal and Williamson Research Centre for Molecular Environmental Science, School of Earth, Atmospheric and Environmental Sciences, The University of Manchester, Manchester M13 9PL, UK.
| | - Gareth T W Law
- Centre for Radiochemistry Research, School of Chemistry, Manchester, M13 9PL, UK
| | - Athanasios Rizoulis
- Research Centre for Radwaste Disposal and Williamson Research Centre for Molecular Environmental Science, School of Earth, Atmospheric and Environmental Sciences, The University of Manchester, Manchester M13 9PL, UK.
| | - Katie Law
- Centre for Radiochemistry Research, School of Chemistry, Manchester, M13 9PL, UK
| | - Joanna C Renshaw
- Research Centre for Radwaste Disposal and Williamson Research Centre for Molecular Environmental Science, School of Earth, Atmospheric and Environmental Sciences, The University of Manchester, Manchester M13 9PL, UK.
| | - Katherine Morris
- Research Centre for Radwaste Disposal and Williamson Research Centre for Molecular Environmental Science, School of Earth, Atmospheric and Environmental Sciences, The University of Manchester, Manchester M13 9PL, UK.
| | - Francis R Livens
- Research Centre for Radwaste Disposal and Williamson Research Centre for Molecular Environmental Science, School of Earth, Atmospheric and Environmental Sciences, The University of Manchester, Manchester M13 9PL, UK. and Centre for Radiochemistry Research, School of Chemistry, Manchester, M13 9PL, UK
| | - Jonathan R Lloyd
- Research Centre for Radwaste Disposal and Williamson Research Centre for Molecular Environmental Science, School of Earth, Atmospheric and Environmental Sciences, The University of Manchester, Manchester M13 9PL, UK.
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14
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Stolz JF. Gaia and her microbiome. FEMS Microbiol Ecol 2016; 93:fiw247. [DOI: 10.1093/femsec/fiw247] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 10/03/2016] [Accepted: 12/07/2016] [Indexed: 01/09/2023] Open
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15
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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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Jaison P, Kumar P, Telmore VM. Liquid chromatographic studies on the behaviour of Pu(III), Pu(IV) and Pu(VI) on a RP stationary phase in presence of α-Hydroxyisobutyric acid as a chelating agent. RADIOCHIM ACTA 2016. [DOI: 10.1515/ract-2016-2673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Since plutonium possesses multiple oxidation states which can coexist in solution, a method for the identification of these oxidation states is important to understand its chemical processes. Liquid chromatographic studies were carried out to compare the chromatographic behaviour of different oxidation states of Pu in presence of the eluent, α-hydroxyisobutyric acid (HIBA). The three oxidation states of Pu viz. Pu(III), Pu(IV) and Pu(VI) were separated under optimised conditions. It was seen that the presence of the complexing agent influences the equilibrium of Pu(III)/(IV) as well as Pu(IV)/(VI) systems. Pu(III) to Pu(IV) conversion was found to be enhanced by high pH and concentration of HIBA whereas a relatively low pH and high concentration of HIBA promotes the conversion of Pu(VI) to Pu(IV).
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Affiliation(s)
- P.G. Jaison
- Fuel Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - Pranaw Kumar
- Fuel Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India
| | - Vijay M. Telmore
- Fuel Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India
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17
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Sorption of plutonium to bacteria and fungi isolated from groundwater and clay samples. J Radioanal Nucl Chem 2016. [DOI: 10.1007/s10967-016-5016-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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18
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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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19
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20
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Muehe EM, Obst M, Hitchcock A, Tyliszczak T, Behrens S, Schröder C, Byrne JM, Michel FM, Krämer U, Kappler A. Fate of Cd during microbial Fe(III) mineral reduction by a novel and Cd-tolerant Geobacter species. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:14099-109. [PMID: 24274146 DOI: 10.1021/es403365w] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Fe(III) (oxyhydr)oxides affect the mobility of contaminants in the environment by providing reactive surfaces for sorption. This includes the toxic metal cadmium (Cd), which prevails in agricultural soils and is taken up by crops. Fe(III)-reducing bacteria can mobilize such contaminants by Fe(III) mineral dissolution or immobilize them by sorption to or coprecipitation with secondary Fe minerals. To date, not much is known about the fate of Fe(III) mineral-associated Cd during microbial Fe(III) reduction. Here, we describe the isolation of a new Geobacter sp. strain Cd1 from a Cd-contaminated field site, where the strain accounts for 10(4) cells g(-1) dry soil. Strain Cd1 reduces the poorly crystalline Fe(III) oxyhydroxide ferrihydrite in the presence of at least up to 112 mg Cd L(-1). During initial microbial reduction of Cd-loaded ferrihydrite, sorbed Cd was mobilized. However, during continuous microbial Fe(III) reduction, Cd was immobilized by sorption to and/or coprecipitation within newly formed secondary minerals that contained Ca, Fe, and carbonate, implying the formation of an otavite-siderite-calcite (CdCO3-FeCO3-CaCO3) mixed mineral phase. Our data shows that microbially mediated turnover of Fe minerals affects the mobility of Cd in soils, potentially altering the dynamics of Cd uptake into food or phyto-remediating plants.
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Affiliation(s)
- E Marie Muehe
- Geomicrobiology, Center for Applied Geosciences, University of Tuebingen , 72076 Tuebingen, Germany
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21
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Exploring the roles of DNA methylation in the metal-reducing bacterium Shewanella oneidensis MR-1. J Bacteriol 2013; 195:4966-74. [PMID: 23995632 DOI: 10.1128/jb.00935-13] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We performed whole-genome analyses of DNA methylation in Shewanella oneidensis MR-1 to examine its possible role in regulating gene expression and other cellular processes. Single-molecule real-time (SMRT) sequencing revealed extensive methylation of adenine (N6mA) throughout the genome. These methylated bases were located in five sequence motifs, including three novel targets for type I restriction/modification enzymes. The sequence motifs targeted by putative methyltranferases were determined via SMRT sequencing of gene knockout mutants. In addition, we found that S. oneidensis MR-1 cultures grown under various culture conditions displayed different DNA methylation patterns. However, the small number of differentially methylated sites could not be directly linked to the much larger number of differentially expressed genes under these conditions, suggesting that DNA methylation is not a major regulator of gene expression in S. oneidensis MR-1. The enrichment of methylated GATC motifs in the origin of replication indicates that DNA methylation may regulate genome replication in a manner similar to that seen in Escherichia coli. Furthermore, comparative analyses suggest that many Gammaproteobacteria, including all members of the Shewanellaceae family, may also utilize DNA methylation to regulate genome replication.
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22
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Decolorization of azo dyes by Geobacter metallireducens. Appl Microbiol Biotechnol 2012; 97:7935-42. [DOI: 10.1007/s00253-012-4545-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 10/20/2012] [Accepted: 10/23/2012] [Indexed: 10/27/2022]
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23
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Zhang X, Ye X, Finneran KT, Zilles JL, Morgenroth E. Interactions betweenClostridium beijerinckiiandGeobacter metallireducensin co-culture fermentation with anthrahydroquinone-2, 6-disulfonate (AH2QDS) for enhanced biohydrogen production from xylose. Biotechnol Bioeng 2012; 110:164-72. [DOI: 10.1002/bit.24627] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 07/19/2012] [Accepted: 07/26/2012] [Indexed: 11/10/2022]
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24
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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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25
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Gorman-Lewis D, Aryal BP, Paunesku T, Vogt S, Lai B, Woloschak GE, Jensen MP. Direct determination of the intracellular oxidation state of plutonium. Inorg Chem 2011; 50:7591-7. [PMID: 21755934 PMCID: PMC3688463 DOI: 10.1021/ic200588p] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Microprobe X-ray absorption near edge structure (μ-XANES) measurements were used to determine directly, for the first time, the oxidation state of intracellular plutonium in individual 0.1-μm(2) areas within single rat pheochromocytoma cells (PC12). The living cells were incubated in vitro for 3 h in the presence of Pu added to the media in different oxidation states (Pu(III), Pu(IV), and Pu(VI)) and in different chemical forms. Regardless of the initial oxidation state or chemical form of Pu presented to the cells, the XANES spectra of the intracellular Pu deposits were always consistent with tetravalent Pu even though the intracellular milieu is generally reducing.
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Affiliation(s)
- Drew Gorman-Lewis
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
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26
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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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27
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Lovley DR, Ueki T, Zhang T, Malvankar NS, Shrestha PM, Flanagan KA, Aklujkar M, Butler JE, Giloteaux L, Rotaru AE, Holmes DE, Franks AE, Orellana R, Risso C, Nevin KP. Geobacter: the microbe electric's physiology, ecology, and practical applications. Adv Microb Physiol 2011; 59:1-100. [PMID: 22114840 DOI: 10.1016/b978-0-12-387661-4.00004-5] [Citation(s) in RCA: 384] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Geobacter species specialize in making electrical contacts with extracellular electron acceptors and other organisms. This permits Geobacter species to fill important niches in a diversity of anaerobic environments. Geobacter species appear to be the primary agents for coupling the oxidation of organic compounds to the reduction of insoluble Fe(III) and Mn(IV) oxides in many soils and sediments, a process of global biogeochemical significance. Some Geobacter species can anaerobically oxidize aromatic hydrocarbons and play an important role in aromatic hydrocarbon removal from contaminated aquifers. The ability of Geobacter species to reductively precipitate uranium and related contaminants has led to the development of bioremediation strategies for contaminated environments. Geobacter species produce higher current densities than any other known organism in microbial fuel cells and are common colonizers of electrodes harvesting electricity from organic wastes and aquatic sediments. Direct interspecies electron exchange between Geobacter species and syntrophic partners appears to be an important process in anaerobic wastewater digesters. Functional and comparative genomic studies have begun to reveal important aspects of Geobacter physiology and regulation, but much remains unexplored. Quantifying key gene transcripts and proteins of subsurface Geobacter communities has proven to be a powerful approach to diagnose the in situ physiological status of Geobacter species during groundwater bioremediation. The growth and activity of Geobacter species in the subsurface and their biogeochemical impact under different environmental conditions can be predicted with a systems biology approach in which genome-scale metabolic models are coupled with appropriate physical/chemical models. The proficiency of Geobacter species in transferring electrons to insoluble minerals, electrodes, and possibly other microorganisms can be attributed to their unique "microbial nanowires," pili that conduct electrons along their length with metallic-like conductivity. Surprisingly, the abundant c-type cytochromes of Geobacter species do not contribute to this long-range electron transport, but cytochromes are important for making the terminal electrical connections with Fe(III) oxides and electrodes and also function as capacitors, storing charge to permit continued respiration when extracellular electron acceptors are temporarily unavailable. The high conductivity of Geobacter pili and biofilms and the ability of biofilms to function as supercapacitors are novel properties that might contribute to the field of bioelectronics. The study of Geobacter species has revealed a remarkable number of microbial physiological properties that had not previously been described in any microorganism. Further investigation of these environmentally relevant and physiologically unique organisms is warranted.
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Affiliation(s)
- Derek R Lovley
- Department of Microbiology and Environmental Biotechnology Center, University of Massachusetts, Amherst, Massachusetts, USA
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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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29
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Law GTW, Geissler A, Lloyd JR, Livens FR, Boothman C, Begg JDC, Denecke MA, Rothe J, Dardenne K, Burke IT, Charnock JM, Morris K. Geomicrobiological redox cycling of the transuranic element neptunium. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2010; 44:8924-8929. [PMID: 21047117 DOI: 10.1021/es101911v] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Microbial processes can affect the environmental behavior of redox sensitive radionuclides, and understanding these reactions is essential for the safe management of radioactive wastes. Neptunium, an alpha-emitting transuranic element, is of particular importance because of its long half-life, high radiotoxicity, and relatively high solubility as Np(V)O(2)(+) under oxic conditions. Here, we describe experiments to explore the biogeochemistry of Np where Np(V) was added to oxic sediment microcosms with indigenous microorganisms and anaerobically incubated. Enhanced Np removal to sediments occurred during microbially mediated metal reduction, and X-ray absorption spectroscopy showed this was due to reduction to poorly soluble Np(IV) on solids. In subsequent reoxidation experiments, sediment-associated Np(IV) was somewhat resistant to oxidative remobilization. These results demonstrate the influence of microbial processes on Np solubility and highlight the critical importance of radionuclide biogeochemistry in nuclear legacy management.
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Affiliation(s)
- Gareth T W Law
- Research Centre for Radwaste and Decommissioning, School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Manchester, M13 9PL, UK
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30
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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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31
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Tai SK, Wu G, Yuan S, Li KC. Genome-wide expression links the electron transfer pathway of Shewanella oneidensis to chemotaxis. BMC Genomics 2010; 11:319. [PMID: 20492688 PMCID: PMC2886065 DOI: 10.1186/1471-2164-11-319] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2009] [Accepted: 05/21/2010] [Indexed: 12/25/2022] Open
Abstract
Background By coupling the oxidation of organic substrates to a broad range of terminal electron acceptors (such as nitrate, metals and radionuclides), Shewanella oneidensis MR-1 has the ability to produce current in microbial fuel cells (MFCs). omcA, mtrA, omcB (also known as mtrC), mtrB, and gspF are some known genes of S. oneidensis MR-1 that participate in the process of electron transfer. How does the cell coordinate the expression of these genes? To shed light on this problem, we obtain the gene expression datasets of MR-1 that are recently public-accessible in Gene Expression Omnibus. We utilize the novel statistical method, liquid association (LA), to investigate the complex pattern of gene regulation. Results Through a web of information obtained by our data analysis, a network of transcriptional regulatory relationship between chemotaxis and electron transfer pathways is revealed, highlighting the important roles of the chemotaxis gene cheA-1, the magnesium transporter gene mgtE-1, and a triheme c-type cytochrome gene SO4572. Conclusion We found previously unknown relationship between chemotaxis and electron transfer using LA system. The study has the potential of helping researchers to overcome the intrinsic metabolic limitation of the microorganisms for improving power density output of an MFC.
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Affiliation(s)
- Shang-Kai Tai
- Institute of Statistical Science, Academia Sinica, Taipei 115, Taiwan
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32
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Gadd GM. Metals, minerals and microbes: geomicrobiology and bioremediation. MICROBIOLOGY-SGM 2009; 156:609-643. [PMID: 20019082 DOI: 10.1099/mic.0.037143-0] [Citation(s) in RCA: 783] [Impact Index Per Article: 52.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Microbes play key geoactive roles in the biosphere, particularly in the areas of element biotransformations and biogeochemical cycling, metal and mineral transformations, decomposition, bioweathering, and soil and sediment formation. All kinds of microbes, including prokaryotes and eukaryotes and their symbiotic associations with each other and 'higher organisms', can contribute actively to geological phenomena, and central to many such geomicrobial processes are transformations of metals and minerals. Microbes have a variety of properties that can effect changes in metal speciation, toxicity and mobility, as well as mineral formation or mineral dissolution or deterioration. Such mechanisms are important components of natural biogeochemical cycles for metals as well as associated elements in biomass, soil, rocks and minerals, e.g. sulfur and phosphorus, and metalloids, actinides and metal radionuclides. Apart from being important in natural biosphere processes, metal and mineral transformations can have beneficial or detrimental consequences in a human context. Bioremediation is the application of biological systems to the clean-up of organic and inorganic pollution, with bacteria and fungi being the most important organisms for reclamation, immobilization or detoxification of metallic and radionuclide pollutants. Some biominerals or metallic elements deposited by microbes have catalytic and other properties in nanoparticle, crystalline or colloidal forms, and these are relevant to the development of novel biomaterials for technological and antimicrobial purposes. On the negative side, metal and mineral transformations by microbes may result in spoilage and destruction of natural and synthetic materials, rock and mineral-based building materials (e.g. concrete), acid mine drainage and associated metal pollution, biocorrosion of metals, alloys and related substances, and adverse effects on radionuclide speciation, mobility and containment, all with immense social and economic consequences. The ubiquity and importance of microbes in biosphere processes make geomicrobiology one of the most important concepts within microbiology, and one requiring an interdisciplinary approach to define environmental and applied significance and underpin exploitation in biotechnology.
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Affiliation(s)
- Geoffrey Michael Gadd
- Division of Molecular Microbiology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
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Plutonium(V/VI) Reduction by the Metal-Reducing Bacteria Geobacter metallireducens GS-15 and Shewanella oneidensis MR-1. Appl Environ Microbiol 2009; 75:3641-7. [PMID: 19363069 DOI: 10.1128/aem.00022-09] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We examined the ability of the metal-reducing bacteria Geobacter metallireducens GS-15 and Shewanella oneidensis MR-1 to reduce Pu(VI) and Pu(V). Cell suspensions of both bacteria reduced oxidized Pu [a mixture of Pu(VI) and Pu(V)] to Pu(IV). The rate of plutonium reduction was similar to the rate of U(VI) reduction obtained under similar conditions for each bacteria. The rates of Pu(VI) and U(VI) reduction by cell suspensions of S. oneidensis were slightly higher than the rates observed with G. metallireducens. The reduced form of Pu was characterized as aggregates of nanoparticulates of Pu(IV). Transmission electron microscopy images of the solids obtained from the cultures after the reduction of Pu(VI) and Pu(V) by S. oneidensis show that the Pu precipitates have a crystalline structure. The nanoparticulates of Pu(IV) were precipitated on the surface of or within the cell walls of the bacteria. The production of Pu(III) was not observed, which indicates that Pu(IV) was the stable form of reduced Pu under these experimental conditions. Experiments examining the ability of these bacteria to use Pu(VI) as a terminal electron acceptor for growth were inconclusive. A slight increase in cell density was observed for both G. metallireducens and S. oneidensis when Pu(VI) was provided as the sole electron acceptor; however, Pu(VI) concentrations decreased similarly in both the experimental and control cultures.
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Xu C, Santschi PH, Zhong JY, Hatcher PG, Francis AJ, Dodge CJ, Roberts KA, Hung CC, Honeyman BD. Colloidal cutin-like substances cross-linked to siderophore decomposition products mobilizing plutonium from contaminated soils. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2008; 42:8211-8217. [PMID: 19068796 DOI: 10.1021/es801348t] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Relatively recently, inorganic colloids have been invoked to reconcile the apparent contradictions between expectations based on classical dissolved-phase Pu transport and field observations of "enhanced" Pu mobility (Kersting et al. Nature 1999, 397, 56-59). A new paradigm for Pu transport is mobilization and transport via biologically produced ligands. This study for the first time reports a new finding of Pu being transported, at sub-pM concentrations, by a cutin-like natural substance containing siderophore-like moieties and virtually all mobile Pu. Most likely, Pu is complexed by chelating groups derived from siderophores that are covalently bound to a backbone of cutin-derived soil degradation products, thus revealing the history of initial exposure to Pu. Features such as amphiphilicity and small size make this macromolecule an ideal collector for actinides and other metals and a vector for their dispersal. Cross-linking to the hydrophobic domains (e.g., by polysaccharides) gives this macromolecule high mobility and a means of enhancing Pu transport. This finding provides a new mechanism for Pu transport through environmental systems that would not have been predicted by Pu transport models.
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Affiliation(s)
- C Xu
- Laboratory for Oceanographic and Environmental Research (LOER), Department of Oceanography Sciences, Texas A&M University, Galveston, Texas 77551, USA
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Fredrickson JK, Romine MF, Beliaev AS, Auchtung JM, Driscoll ME, Gardner TS, Nealson KH, Osterman AL, Pinchuk G, Reed JL, Rodionov DA, Rodrigues JLM, Saffarini DA, Serres MH, Spormann AM, Zhulin IB, Tiedje JM. Towards environmental systems biology of Shewanella. Nat Rev Microbiol 2008; 6:592-603. [PMID: 18604222 DOI: 10.1038/nrmicro1947] [Citation(s) in RCA: 629] [Impact Index Per Article: 39.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Bacteria of the genus Shewanella are known for their versatile electron-accepting capacities, which allow them to couple the decomposition of organic matter to the reduction of the various terminal electron acceptors that they encounter in their stratified environments. Owing to their diverse metabolic capabilities, shewanellae are important for carbon cycling and have considerable potential for the remediation of contaminated environments and use in microbial fuel cells. Systems-level analysis of the model species Shewanella oneidensis MR-1 and other members of this genus has provided new insights into the signal-transduction proteins, regulators, and metabolic and respiratory subsystems that govern the remarkable versatility of the shewanellae.
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Affiliation(s)
- James K Fredrickson
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA. ;
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