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Dalai S, Sivan M, Husain MA, Alam N, Landrot G, Biswas A. Mechanistic Insight into the Abiotic Interactions of Selenate and Selenite with Natural Organic Matter. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:16595-16605. [PMID: 37855829 DOI: 10.1021/acs.est.3c06276] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2023]
Abstract
Natural organic matter (NOM) decreases the selenium (Se) mobility in soil and sediment. Biotic dissimilatory reduction of selenate and selenite and assimilation of the reduced Se species into biomolecules are thought to be primarily responsible for this decreased Se mobility. However, the possibility of Se immobilization due to the abiotic interaction of Se species with NOM is still poorly understood. Equilibrating selenate and selenite with a model NOM (Pahokee peat soil), followed by X-ray absorption spectroscopic analysis, this study shows that the NOM can abiotically reduce highly mobile selenate into relatively less mobile selenite. NOM can sorb Se species, especially selenite, considerably. Preloading of the NOM with Fe(III) increases the sorption of selenite and selenate by several orders of magnitude. Modeling of the Se and Fe K-edge EXAFS data revealed that Se species are sorbed to NOM due to indirect complexation with the organically complexed Fe(O,OH)6 octahedra through the corner- (2C) and edge-sharing (1E) and direct complexation with the oxygen-containing functional groups of the NOM. This study concludes that the abiotic reduction and complexation of the Se species with NOM can be the additional or alternative route of Se immobilization in the NOM-rich soil and sediment.
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Affiliation(s)
- Subhashree Dalai
- Environmental Geochemistry Laboratory, Department of Earth and Environmental Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal Bypass Road, Bhauri 462066, Madhya Pradesh, India
| | - Malavika Sivan
- Environmental Geochemistry Laboratory, Department of Earth and Environmental Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal Bypass Road, Bhauri 462066, Madhya Pradesh, India
| | - Mohd Amir Husain
- Environmental Geochemistry Laboratory, Department of Earth and Environmental Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal Bypass Road, Bhauri 462066, Madhya Pradesh, India
| | - Naved Alam
- Environmental Geochemistry Laboratory, Department of Earth and Environmental Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal Bypass Road, Bhauri 462066, Madhya Pradesh, India
| | - Gautier Landrot
- SOLEIL Synchrotron, L'Orme des Merisiers, Saint-Aubin, BP 48, Gif-sur-Yvette Cedex 91192, France
| | - Ashis Biswas
- Environmental Geochemistry Laboratory, Department of Earth and Environmental Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal Bypass Road, Bhauri 462066, Madhya Pradesh, India
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Microbial Community Composition Correlates with Metal Sorption in an Ombrotrophic Boreal Bog: Implications for Radionuclide Retention. SOIL SYSTEMS 2021. [DOI: 10.3390/soilsystems5010019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Microbial communities throughout the 6.5 m depth profile of a boreal ombrotrophic bog were characterized using amplicon sequencing of archaeal, fungal, and bacterial marker genes. Microbial populations and their relationship to oxic and anoxic batch sorption of radionuclides (using radioactive tracers of I, Se, Cs, Ni, and Ag) and the prevailing metal concentrations in the natural bog was investigated. The majority of the detected archaea belonged to the Crenarchaeota, Halobacterota, and Thermoplasmatota, whereas the fungal communities consisted of Ascomycota, Basidiomycota, and unclassified fungi. The bacterial communities consisted mostly of Acidobacteriota, Proteobacteria, and Chloroflexi. The occurrence of several microbial genera were found to statistically significantly correlate with metal concentrations as well as with Se, Cs, I, and Ag batch sorption data. We suggest that the metal concentrations of peat, gyttja, and clay layers affect the composition of the microbial populations in these nutrient-low conditions and that particularly parts of the bacterial and archaeal communities tolerate high concentrations of potentially toxic metals and may concurrently contribute to the total retention of metals and radionuclides in this ombrotrophic environment. In addition, the varying metal concentrations together with chemical, mineralogical, and physical factors may contribute to the shape of the total archaeal and bacterial populations and most probably shifts the populations for more metal resistant genera.
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Knuutinen J, Bomberg M, Kemell M, Lusa M. Ni(II) Interactions in Boreal Paenibacillus sp., Methylobacterium sp., Paraburkholderia sp., and Pseudomonas sp. Strains Isolated From an Acidic, Ombrotrophic Bog. Front Microbiol 2019; 10:2677. [PMID: 31849859 PMCID: PMC6901981 DOI: 10.3389/fmicb.2019.02677] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 11/04/2019] [Indexed: 12/04/2022] Open
Abstract
The uptake of nickel [Ni(II)] by Paenibacillus sp., Methylobacterium sp., Paraburkholderia sp., and Pseudomonas sp. strains isolated from a boreal bog was studied using batch experiments. All strains removed Ni(II) from the solution and the uptake efficiency was affected by the nutrient source, incubation temperature, time, and pH. As highest Ni uptake (with a maximum Kd of 1890 L/kg DW) was recorded for the Pseudomonas sp. strains, these bacteria were used in the following protein expression (SDS-PAGE and MALDI-TOFF), transmission electron microscopy (TEM) and EDS experiments. In addition, Freundlich and Langmuir sorption isotherms were determined. In the Ni(II) treated cells, dense crystalline intra-cellular accumulations were observed in TEM examinations, which were identified as Ni accumulations using EDS. SDS-PAGE and MALDI-TOFF spectra of Ni(II) treated cells showed several changes in the protein profiles, which can indicate active accumulation of Ni in these bacteria. Concurrently, we observed Ni(II) uptake to follow Freundlich and Langmuir isotherms, suggesting straight cellular biosorption in addition to the intra-cellular accumulation. The role of cellular (cell membrane and cell wall) functional groups involved in Ni(II) binding were therefore studied using Fourier transformation infrared spectroscopy. These analyses supported the potential role of the alcoholic hydroxyl, carboxyl and amine groups in Ni(II) binding in these bacteria, therefore suggesting two different Ni(II) uptake mechanisms; (i) intra-cellular accumulation [possibly connected to detoxification of Ni(II)], and (ii) straight biosorption on cell membrane/wall functional groups.
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Affiliation(s)
- Jenna Knuutinen
- Department of Chemistry, University of Helsinki, Helsinki, Finland
| | - Malin Bomberg
- VTT Technical Research Centre of Finland, Espoo, Finland
| | - Marianna Kemell
- Department of Chemistry, University of Helsinki, Helsinki, Finland
| | - Merja Lusa
- Department of Chemistry, University of Helsinki, Helsinki, Finland
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Lusa M, Help H, Honkanen AP, Knuutinen J, Parkkonen J, Kalasová D, Bomberg M. The reduction of selenium(IV) by boreal Pseudomonas sp. strain T5-6-I - Effects on selenium(IV) uptake in Brassica oleracea. ENVIRONMENTAL RESEARCH 2019; 177:108642. [PMID: 31430668 DOI: 10.1016/j.envres.2019.108642] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 08/07/2019] [Accepted: 08/08/2019] [Indexed: 06/10/2023]
Abstract
Selenium (Se) is an essential micronutrient but toxic when taken in excessive amounts. Therefore, understanding the metabolic processes related to selenium uptake and bacteria-plant interactions coupled with selenium metabolism are of high importance. We cultivated Brassica oleracea with the previously isolated heterotrophic aerobic Se(IV)-reducing Pseudomonas sp. T5-6-I strain to better understand the phenomena of bacteria-mediated Se(IV) reduction on selenium availability to the plants. B. oleracea grown on Murashige and Skoog medium (MS-salt agar) with and without of Pseudomonas sp. were amended with Se(IV)/75Se(IV), and selenium transfer into plants was studied using autoradiography and gamma spectroscopy. XANES was in addition used to study the speciation of selenium in the B. oleracea plants. In addition, the effects of Se(IV) on the protein expression in B. oleracea was studied using HPLC-SEC. TEM and confocal microscopy were used to follow the bacterial/Se-aggregate accumulation in plants and the effects of bacterial inoculation on root-hair growth. In the tests using 75Se(IV) on average 130% more selenium was translocated to the B. oleracea plants grown with Pseudomonas sp. compared to the plants grown with selenium, but without Pseudomonas sp.. In addition, these bacteria notably increased root hair density. Changes in the protein expression of B. oleracea were observed on the ∼30-58 kDa regions in the Se(IV) treated samples, probably connected e.g. to the oxidative stress induced by Se(IV) or expression of proteins connected to the Se(IV) metabolism. Based on the XANES measurements, selenium appears to accumulate in B. oleracea mainly in organic C-Se-H and C-Se-C bonds with and without bacteria inoculation. We conclude that the Pseudomonas sp. T5-6-I strain seems to contribute positively to the selenium accumulation in plants, establishing the high potential of Se0-producing bacteria in the use of phytoremediation and biofortification of selenium.
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Affiliation(s)
- Merja Lusa
- Department of Chemistry, Radiochemistry, Faculty of Science, University of Helsinki, Finland.
| | - Hanna Help
- Department of Physics, X-Ray Laboratory, Faculty of Science, University of Helsinki, Finland
| | - Ari-Pekka Honkanen
- Department of Physics, X-Ray Laboratory, Faculty of Science, University of Helsinki, Finland
| | - Jenna Knuutinen
- Department of Chemistry, Radiochemistry, Faculty of Science, University of Helsinki, Finland
| | | | - Dominika Kalasová
- CEITEC - Central European Institute of Technology, Brno University of Technology, Brno, Czech Republic
| | - Malin Bomberg
- Material Recycling and Geotechnology, VTT, Technical Research Center of Finland, Espoo, Finland
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Lazareva EV, Myagkaya IN, Kirichenko IS, Gustaytis MA, Zhmodik SM. Interaction of natural organic matter with acid mine drainage: In-situ accumulation of elements. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 660:468-483. [PMID: 30640114 DOI: 10.1016/j.scitotenv.2018.12.467] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 12/30/2018] [Accepted: 12/30/2018] [Indexed: 06/09/2023]
Abstract
Natural organic matter (NOM) within the dispersion train of Novo-Ursk tailings (Salair Ridge, Kemerovo region, Russia) is composed of remnant sedge peat mounds and is located either on the surface or is buried under cyanide wastes. The organic material interacts with AMD and with the wastes, which leaves imprint on its composition. This interaction produces geochemical anomalies (g/t: 1582 Cu, 41,300 Zn, 6060 Se, 11,700 Hg, 114-155 Au, 534 Ag, 416 I). The contents of elements depend on Fe in three groups of NOM samples that contain <10 wt% Fe (group I), 10-22 wt% Fe (group II), and >22 wt% Fe (group III). NOM with higher Fe enrichment contains less Cu, Zn, Se, Hg, Ag and I, as well as Cd, Ba, Sr and Rb, Y, Zr, Nb, Mo, Sn, Sb, and Te but more As. Yet, gold may reach high concentrations in NOM with any Fe contents. Accumulation of elements by NOM during its prolonged interaction with wastes and AMD is maintained by physical, chemical, biochemical, and mineralogical processes. They are, respectively, migration of waters controlled by permeability of material in the dispersion train depending on its grain sizes and by AMD flow direction; oxidative dissolution of sulfides, complexing, and adsorption on organic matter and Fe(III) hydroxides; microbial mediation; and secondary mineralization. The chemistry of waters interacting with NOM at the time of its deposition can be reconstructed with regard to several factors, including microbial mediation. Namely, local geochemical anomalies with ultrahigh element concentrations may arise because microorganisms can immobilize Hg to make it less toxic; sulfate-reducing bacteria can maintain precipitation of Zn, Cu, and Cd sulfides; microbial activity can mediate redistribution of elements between clastic and organic materials, etc. The inferred inheritance of AMD geochemical signatures by NOM has implications for the conditions and mechanisms of element accumulation.
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Affiliation(s)
- E V Lazareva
- V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, Koptyuga Ave. 3, Novosibirsk 630090, Russia
| | - I N Myagkaya
- V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, Koptyuga Ave. 3, Novosibirsk 630090, Russia.
| | - I S Kirichenko
- V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, Koptyuga Ave. 3, Novosibirsk 630090, Russia
| | - M A Gustaytis
- V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, Koptyuga Ave. 3, Novosibirsk 630090, Russia
| | - S M Zhmodik
- V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, Koptyuga Ave. 3, Novosibirsk 630090, Russia
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Vogel M, Fischer S, Maffert A, Hübner R, Scheinost AC, Franzen C, Steudtner R. Biotransformation and detoxification of selenite by microbial biogenesis of selenium-sulfur nanoparticles. JOURNAL OF HAZARDOUS MATERIALS 2018; 344:749-757. [PMID: 29156387 DOI: 10.1016/j.jhazmat.2017.10.034] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 09/27/2017] [Accepted: 10/16/2017] [Indexed: 05/27/2023]
Abstract
This study combines the interaction between the toxic oxyanions selenite and selenate and the plant growth promoting bacterium Azospirillum brasilense with a comprehensive characterization of the formed selenium particles. As selenium is an essential trace element, but also toxic in high concentrations, its state of occurrence in nature is of major concern. Growth of the bacterium was affected by selenite (1-5mM) only, observable as a prolonged growth lag-phase of 3days. Subsequently, selenite reduction occurred under aerobic conditions resulting in extracellularly formed insoluble Se0 particles. Complementary studies by microscopic and spectroscopic techniques revealed the particles to be homogeneous and stable Se8-nSn structured spheres with an average size of 400nm and highly negative surface charge of -18mV in the neutral pH range. As this is the first study showing Azospirillum brasilense being able to biotransform selenite to selenium particles containing a certain amount of sulfur, even if environmental waters supplemented with selenite were used, they may significantly contribute to the biogeochemical cycling of both elements in soil as well as to their soil-plant transfer. Therefore, microbial biotransformation of selenite under certain circumstances may be used for various bio-remediation and bio-technological applications.
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Affiliation(s)
- M Vogel
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Resource Ecology, Bautzner Landstrasse 400, D-01328 Dresden, Germany; Helmholtz-Zentrum Dresden-Rossendorf e.V., Helmholtz Institute Freiberg for Resource Technology, Bautzner Landstrasse 400, D-01328 Dresden, Germany.
| | - S Fischer
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Resource Ecology, Bautzner Landstrasse 400, D-01328 Dresden, Germany.
| | - A Maffert
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Resource Ecology, Bautzner Landstrasse 400, D-01328 Dresden, Germany; Helmholtz-Zentrum Dresden-Rossendorf e.V., Helmholtz Institute Freiberg for Resource Technology, Bautzner Landstrasse 400, D-01328 Dresden, Germany.
| | - R Hübner
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Ion-Beam Physics and Materials Research, Bautzner Landstrasse 400, D-01328 Dresden, Germany.
| | - A C Scheinost
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Resource Ecology, Bautzner Landstrasse 400, D-01328 Dresden, Germany; European Synchrotron Radiation Facility, Rossendorf Beamline, BP 220, F-38043 Grenoble, France.
| | - C Franzen
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Resource Ecology, Bautzner Landstrasse 400, D-01328 Dresden, Germany.
| | - R Steudtner
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Resource Ecology, Bautzner Landstrasse 400, D-01328 Dresden, Germany.
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Lusa M, Knuutinen J, Bomberg M. Uptake and reduction of Se(IV) in two heterotrophic aerobic Pseudomonads strains isolated from boreal bog environment. AIMS Microbiol 2017; 3:798-814. [PMID: 31294190 PMCID: PMC6604954 DOI: 10.3934/microbiol.2017.4.798] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 09/28/2017] [Indexed: 12/02/2022] Open
Abstract
Selenite (Se(IV), SeO32−) uptake and the effect of selenite supplement on protein synthesis was investigated in two Pseudomonas sp. strains isolated from a boreal bog. These aerobic bacteria efficiently reduced Se(IV) with intracellular reduced Se0 observed in the cytoplasm under dark aerobic conditions. The proteome analysis of Se(IV) supplement and temperature responses by SDS-PAGE gel electrophoresis showed variations in the protein expression on the 40–60 kDa regions following these stress factors, probably through enzymes associated to oxidative stress or temperature adaptation. NO3−/NO2−/SO42− addition enhanced Se(IV) uptake in both bacteria, but Se(IV) uptake sustained also under sulphur and nitrogen starvation. Our findings suggest two different transport mechanisms for Se(IV) uptake in these Pseudomonas sp. strains; a low affinity transport system up-regulated by NO3−/NO2−/SO42− and a distinct Se(IV)O32− regulated transport system. Following transport, Se(IV) is reduced in the cytoplasm, forming Se0 granules, visible in TEM and verified using EDX.
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Affiliation(s)
- Merja Lusa
- Department of Chemistry, Radiochemistry, University of Helsinki, P.O. Box 55, 00014 Helsinki, Finland
| | - Jenna Knuutinen
- Department of Chemistry, Radiochemistry, University of Helsinki, P.O. Box 55, 00014 Helsinki, Finland
| | - Malin Bomberg
- VTT Technical Research Centre of Finland, Espoo, Finland
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Saryg-Ool BY, Myagkaya IN, Kirichenko IS, Gustaytis MA, Shuvaeva OV, Zhmodik SM, Lazareva EV. Redistribution of elements between wastes and organic-bearing material in the dispersion train of gold-bearing sulfide tailings: Part I. Geochemistry and mineralogy. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 581-582:460-471. [PMID: 28088549 DOI: 10.1016/j.scitotenv.2016.12.154] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 12/22/2016] [Accepted: 12/22/2016] [Indexed: 06/06/2023]
Abstract
Migration and redistribution of elements during prolonged interaction of cyanide wastes with the underlying natural organic-bearing material have been studied in two ~40cm deep cores that sample primary ores and their weathering profile (wastes I and II, respectively) in the dispersion train of gold-bearing sulfide tailings in Siberia. Analytical results of SR-XRF, whole-rock XRF, AAS, CHNS, and SEM measurements of core samples show high K, Sr, Ti, and Fe enrichments and correlation of P2O5 and Mn with LOI and Corg. Organic material interlayered or mixed with the wastes accumulates Cu, Zn, Se, Cd, Ag, Au, and Hg. The peat that contacts wastes II bears up to 3wt.% Zn, 1000g/t Se, 100g/t Cd, and 8000g/t Hg. New phases of Zn and Hg sulfides and Hg selenides occur as abundant sheaths over bacterial cells suggesting microbial mediation in sorption of elements. Organic-bearing material in the cores contains 10-30g/t Au in 2-5cm thick intervals, both within and outside the intervals rich in sulfides and selenides. Most of gold is invisible but reaches 345g/t and forms 50nm to 1.5μm Au0 particles in a thin 2-3cm interval of organic remnants mixed with wastes I. Vertical and lateral infiltration of AMD waters in peat and oxidative dissolution of wastes within the dispersion train of the Ursk tailings lead to redistribution of elements and their accumulation by combined physical (material's permeability, direction AMD), chemical (complexing, sorption by organic matter and Fe(III) hydroxides) and biochemical (metabolism of sulfate-reducing bacteria) processes. The accumulated elements form secondary sulfates, and Hg and Zn selenides. The results provide insights into accumulation of elements in the early history of coal and black shale deposits and have implications for remediation of polluted areas and for secondary enrichment technologies.
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Affiliation(s)
- B Yu Saryg-Ool
- Sobolev Institute of Geology and Mineralogy, Siberian Branch of Russian Academy of Sciences, 3, Koptyug Avenue, Novosibirsk 630090, Russia; Novosibirsk State University, 2, Pirogov Str., Novosibirsk 630090, Russia
| | - I N Myagkaya
- Sobolev Institute of Geology and Mineralogy, Siberian Branch of Russian Academy of Sciences, 3, Koptyug Avenue, Novosibirsk 630090, Russia; National Research Tomsk Polytechnical University, 30, Lenin Avenue, Tomsk 634050, Russia.
| | - I S Kirichenko
- Sobolev Institute of Geology and Mineralogy, Siberian Branch of Russian Academy of Sciences, 3, Koptyug Avenue, Novosibirsk 630090, Russia
| | - M A Gustaytis
- Sobolev Institute of Geology and Mineralogy, Siberian Branch of Russian Academy of Sciences, 3, Koptyug Avenue, Novosibirsk 630090, Russia; Novosibirsk State University, 2, Pirogov Str., Novosibirsk 630090, Russia
| | - O V Shuvaeva
- Novosibirsk State University, 2, Pirogov Str., Novosibirsk 630090, Russia; Nikolaev Institute of Inorganic Chemistry, Siberian Branch of Russian Academy of Sciences, 3, Lavrentiev avenue, Novosibirsk 630090, Russia
| | - S M Zhmodik
- Sobolev Institute of Geology and Mineralogy, Siberian Branch of Russian Academy of Sciences, 3, Koptyug Avenue, Novosibirsk 630090, Russia; Novosibirsk State University, 2, Pirogov Str., Novosibirsk 630090, Russia
| | - E V Lazareva
- Sobolev Institute of Geology and Mineralogy, Siberian Branch of Russian Academy of Sciences, 3, Koptyug Avenue, Novosibirsk 630090, Russia
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Söderlund M, Virkanen J, Holgersson S, Lehto J. Sorption and speciation of selenium in boreal forest soil. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2016; 164:220-231. [PMID: 27521902 DOI: 10.1016/j.jenvrad.2016.08.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 08/03/2016] [Accepted: 08/04/2016] [Indexed: 06/06/2023]
Abstract
Sorption and speciation of selenium in the initial chemical forms of selenite and selenate were investigated in batch experiments on humus and mineral soil samples taken from a 4-m deep boreal forest soil excavator pit on Olkiluoto Island, on the Baltic Sea coast in southwestern Finland. The HPLC-ICP-MS technique was used to monitor any possible transformations in the selenium liquid phase speciation and to determine the concentrations of selenite and selenate in the samples for calculation of the mass distribution coefficient, Kd, for both species. Both SeO32- and SeO42- proved to be resistant forms in the prevailing soil conditions and no changes in selenium liquid phase speciation were seen in the sorption experiments in spite of variations in the initial selenium species, incubation time or conditions, pH, temperature or microbial activity. Selenite sorption on the mineral soil increased with time in aerobic conditions whilst the opposite trend was seen for the anaerobic soil samples. Selenite retention correlated with the contents of organic matter and weakly crystalline oxides of aluminum and iron, solution pH and the specific surface area. Selenate exhibited poorer sorption on soil than selenite and on average the Kd values were 27-times lower. Mineral soil was more efficient in retaining selenite and selenate than humus, implicating the possible importance of weakly crystalline aluminum and iron oxides for the retention of oxyanions in Olkiluoto soil. Sterilization of the soil samples decreased the retention of selenite, thus implying some involvement of soil microbes in the sorption processes or a change in sample composition, but it produced no effect for selenate. There was no sorption of selenite by quartz, potassium feldspar, hornblende or muscovite. Biotite showed the best retentive properties for selenite in the model soil solution at about pH 8, followed by hematite, plagioclase and chlorite. The Kd values for these minerals were 18, 14, 8 and 7 L/kg, respectively. It is proposed that selenite sorption is affected by the structural Fe(II) in biotite, which is capable of inducing the reduction of SeO32- to Se(0). Selenite probably forms a surface complex with Fe(III) atoms on the surface of hematite, thus explaining its retention on this mineral. None of the minerals retained selenate to any extent.
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Affiliation(s)
- Mervi Söderlund
- Laboratory of Radiochemistry, Department of Chemistry, P.O. BOX 55, FIN-00014 University of Helsinki, Finland.
| | - Juhani Virkanen
- Department of Geosciences and Geography, P.O. Box 64, FIN-00014 University of Helsinki, Finland.
| | - Stellan Holgersson
- Nuclear Chemistry, Department of Chemical Engineering, Chalmers University of Technology, Kemivägen 4, SE-41296 Gothenburg, Sweden.
| | - Jukka Lehto
- Laboratory of Radiochemistry, Department of Chemistry, P.O. BOX 55, FIN-00014 University of Helsinki, Finland.
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Khoei NS, Lampis S, Zonaro E, Yrjälä K, Bernardi P, Vallini G. Insights into selenite reduction and biogenesis of elemental selenium nanoparticles by two environmental isolates of Burkholderia fungorum. N Biotechnol 2016; 34:1-11. [PMID: 27717878 DOI: 10.1016/j.nbt.2016.10.002] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 07/11/2016] [Accepted: 10/03/2016] [Indexed: 11/30/2022]
Abstract
Microorganisms capable of transforming toxic selenium oxyanions into non-toxic elemental selenium (Se°) may be considered as biocatalysts for the production of selenium nanoparticles (SeNPs), eventually exploitable in different biotechnological applications. Two Burkholderia fungorum strains (B. fungorum DBT1 and B. fungorum 95) were monitored during their growth for both capacity and efficiency of selenite (SeO32-) reduction and elemental selenium formation. Both strains are environmental isolates in origin: B. fungorum DBT1 was previously isolated from an oil refinery drainage, while B. fungorum 95 has been enriched from inner tissues of hybrid poplars grown in a soil contaminated by polycyclic aromatic hydrocarbons. Our results showed that B. fungorum DBT1 is able to reduce 0.5mM SeO32- to Se° when cultured aerobically in liquid medium at 27°C, while B. fungorum 95 can reduce more than 1mM SeO32- to Se° within 96h under the same growth conditions, with the appearance of SeNPs in cultures of both bacterial strains. Biogenic SeNPs were spherical, with pH-dependent charge and an average hydrodynamic diameter of 170nm and 200nm depending on whether they were produced by B. fungorum 95 or B. fungorum DBT1, respectively. Electron microscopy analyses evidenced that Se nanoparticles occurred intracellularly and extracellularly. The mechanism of SeNPs formation can be tentatively attributed to cytoplasmic enzymatic activation mediated by electron donors. Biogenic nanoparticles were then probably released outside the bacterial cells as a consequence of a secretory process or cell lysis. Nevertheless, formation of elemental selenium nanoparticles under aerobic conditions by B. fungorum DBT1 and B. fungorum 95 is likely due to intracellular reduction mechanisms. Biomedical and other high tech sectors might exploit these biogenic nanoparticles in the near future, once fully characterized and tested for their multiple properties.
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Affiliation(s)
- Nazanin Seyed Khoei
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona, Italy.
| | - Silvia Lampis
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona, Italy.
| | - Emanuele Zonaro
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona, Italy
| | - Kim Yrjälä
- MEM-group, Department of Biosciences, University of Helsinki, 00014 Helsinki, Finland
| | - Paolo Bernardi
- Department of Neurological and Movement Sciences, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy
| | - Giovanni Vallini
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona, Italy
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