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Guo Q, Ye J, Zeng J, Chen L, Korpelainen H, Li C. Selenium species transforming along soil-plant continuum and their beneficial roles for horticultural crops. HORTICULTURE RESEARCH 2023; 10:uhac270. [PMID: 36789256 PMCID: PMC9923214 DOI: 10.1093/hr/uhac270] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 12/01/2022] [Indexed: 05/15/2023]
Abstract
Selenium (Se) acquirement from daily diet can help reduce the risk of many diseases. The edible parts of crop plants are the main source of dietary Se, while the Se content in crops is determined by Se bioavailability in soil. We summarize recent research on the biogeochemical cycle of Se driven by specific microorganisms and emphasize the oxidizing process in the Se cycle. Moreover, we discuss how plant root exudates and rhizosphere microorganisms affect soil Se availability. Finally, we cover beneficial microorganisms, including endophytes, that promote crop quality and improve crop tolerance to environmental stresses. Se availability to plants depends on the balance between adsorption and desorption, reduction, methylation and oxidation, which are determined by interactions among soil properties, microbial communities and plants. Reduction and methylation processes governed by bacteria or fungi lead to declined Se availability, while Se oxidation regulated by Se-oxidizing microorganisms increases Se availability to plants. Despite a much lower rate of Se oxidization compared to reduction and methylation, the potential roles of microbial communities in increasing Se bioavailability are probably largely underestimated. Enhancing Se oxidation and Se desorption are crucial for the promotion of Se bioavailability and uptake, particularly in Se-deficient soils. Beneficial roles of Se are reported in terms of improved crop growth and quality, and enhanced protection against fungal diseases and abiotic stress through improved photosynthetic traits, increased sugar and amino acid contents, and promoted defense systems. Understanding Se transformation along the plant-soil continuum is crucial for agricultural production and even for human health.
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Affiliation(s)
- Qingxue Guo
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China
| | - Jianhui Ye
- College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Jianming Zeng
- Tea Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310008, China
| | - Liang Chen
- Tea Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310008, China
| | - Helena Korpelainen
- Department of Agricultural Sciences, Viikki Plant Science Centre, University of Helsinki, P.O. Box 27, FI-00014, Finland
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Solid-Water Interface Interaction of Selenium with Fe(II)-Bearing Minerals and Aqueous Fe(II) and S(-II) Ions in the Near-Field of the Radioactive Waste Disposal System. Int J Mol Sci 2022; 24:ijms24010315. [PMID: 36613759 PMCID: PMC9820544 DOI: 10.3390/ijms24010315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 12/09/2022] [Accepted: 12/20/2022] [Indexed: 12/28/2022] Open
Abstract
Selenium can be highly toxic in excess for both animals and humans. However, since its mobile forms can be easily adsorbed with ferric minerals, its mobility in the natural oxic environment is generally not an issue. Still, the removal and immobilization of the long-lived radioactive isotope 79Se from the contaminated anoxic waters is currently a significant concern. 79Se can be accessible in the case of radionuclides' leaching from radioactive waste disposals, where anoxic conditions prevail and where ferrous ions and Fe(II)-bearing minerals predominate after corrosion processes (e.g., magnetite). Therefore, reductive and adsorptive immobilizations by Fe(II)-bearing minerals are the primary mechanisms for removing redox-sensitive selenium. Even though the information on the sorptive interactions of selenium and Fe(II)-bearing minerals seems to be well documented, this review focuses specifically on the state of the available information on the effects of the redox properties of Fe(II)-bearing solid phases (e.g., ferrous oxides, hydroxides, sulfides, and carbonates) on selenium speciation via redox transformation and co-occurring coprecipitation.
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3
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Song B, Weijma J, Buisman CJN, van der Weijden RD. How sulfur species can accelerate the biological immobilization of the toxic selenium oxyanions and promote stable hexagonal Se 0 formation. JOURNAL OF HAZARDOUS MATERIALS 2022; 437:129367. [PMID: 35897181 DOI: 10.1016/j.jhazmat.2022.129367] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 06/07/2022] [Accepted: 06/09/2022] [Indexed: 06/15/2023]
Abstract
Toxic selenium oxyanions and sulfur species are often jointly present in contaminated waters and soils. This study investigated the effect on kinetics and resulting products for bio-reduction of selenium oxyanions in the presence of biologically produced sulfur resulting from bio-oxidation of sulfide in (bio)gas-desulfurization (bio-S0) and of sulfate. Selenite and selenate (~2 mmol L-1) bio-reduction was studied in batch up to 28 days at 30 oC and pH 7 using lactic acid and a sulfate-reducing sludge, 'Emmtec'. Bio-S0 addition increased the selenite removal rate, but initially slightly decreased selenate reduction rates. Selenite reacted with biologically generated sulfide resulting in selenium-sulfur, which upon further bio-reduction creates a sulfur bio-reduction cycle. Sulfate addition increased the bio-reduction rate for both selenite and sulfate. Bio-S0 or sulfate promoted hexagonal selenium formation, whereas without these, mostly amorphous Se0 resulted. With another inoculum, 'Eerbeek', bio-S0 accelerated the selenite reduction rate less than for 'Emmtec' because of lower sulfur and higher selenite bio-reduction rates. Bio-S0 addition increased the selenate reduction rate slightly and accelerated hexagonal selenium formation. Hexagonal selenium formation is advantageous because it facilitates separation and recovery and is less mobile and toxic than amorphous Se0. Insights into the interaction between selenium and sulfur bio-reduction are valuable for understanding environmental pathways and considerations regarding remediation and recovery.
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Affiliation(s)
- B Song
- Department of Environmental Technology, Wageningen University and Research, the Netherlands
| | - J Weijma
- Department of Environmental Technology, Wageningen University and Research, the Netherlands
| | - C J N Buisman
- Department of Environmental Technology, Wageningen University and Research, the Netherlands
| | - R D van der Weijden
- Department of Environmental Technology, Wageningen University and Research, the Netherlands.
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4
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Ho MS, Vettese GF, Morris K, Lloyd JR, Boothman C, Bower WR, Shaw S, Law GTW. Retention of immobile Se(0) in flow-through aquifer column systems during bioreduction and oxic-remobilization. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 834:155332. [PMID: 35460788 DOI: 10.1016/j.scitotenv.2022.155332] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 04/12/2022] [Accepted: 04/12/2022] [Indexed: 06/14/2023]
Abstract
Selenium (Se) is a toxic contaminant with multiple anthropogenic sources, including 79Se from nuclear fission. Se mobility in the geosphere is generally governed by its oxidation state, therefore understanding Se speciation under variable redox conditions is important for the safe management of Se contaminated sites. Here, we investigate Se behavior in sediment groundwater column systems. Experiments were conducted with environmentally relevant Se concentrations, using a range of groundwater compositions, and the impact of electron-donor (i.e., biostimulation) and groundwater sulfate addition was examined over a period of 170 days. X-Ray Absorption Spectroscopy and standard geochemical techniques were used to track changes in sediment associated Se concentration and speciation. Electron-donor amended systems with and without added sulfate retained up to 90% of added Se(VI)(aq), with sediment associated Se speciation dominated by trigonal Se(0) and possibly trace Se(-II); no Se colloid formation was observed. The remobilization potential of the sediment associated Se species was then tested in reoxidation and seawater intrusion perturbation experiments. In all treatments, sediment associated Se (i.e., trigonal Se(0)) was largely resistant to remobilization over the timescale of the experiments (170 days). However, in the perturbation experiments, less Se was remobilized from sulfidic sediments, suggesting that previous sulfate-reducing conditions may buffer Se against remobilization and migration.
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Affiliation(s)
- Mallory S Ho
- Radiochemistry Unit, Department of Chemistry, University of Helsinki, 00014, Finland
| | - Gianni F Vettese
- Radiochemistry Unit, Department of Chemistry, University of Helsinki, 00014, Finland
| | - Katherine Morris
- Department of Earth and Environmental Sciences, University of Manchester, M13 9PL, UK.
| | - Jonathan R Lloyd
- Department of Earth and Environmental Sciences, University of Manchester, M13 9PL, UK
| | - Christopher Boothman
- Department of Earth and Environmental Sciences, University of Manchester, M13 9PL, UK
| | - William R Bower
- Radiochemistry Unit, Department of Chemistry, University of Helsinki, 00014, Finland
| | - Samuel Shaw
- Department of Earth and Environmental Sciences, University of Manchester, M13 9PL, UK
| | - Gareth T W Law
- Radiochemistry Unit, Department of Chemistry, University of Helsinki, 00014, Finland.
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Yang H, Yang X, Ning Z, Kwon SY, Li ML, Tack FMG, Kwon EE, Rinklebe J, Yin R. The beneficial and hazardous effects of selenium on the health of the soil-plant-human system: An overview. JOURNAL OF HAZARDOUS MATERIALS 2022; 422:126876. [PMID: 34416699 DOI: 10.1016/j.jhazmat.2021.126876] [Citation(s) in RCA: 55] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/25/2021] [Accepted: 08/07/2021] [Indexed: 06/13/2023]
Abstract
Selenium (Se), which can be both hazardous and beneficial to plants, animals and humans, plays a pivotal role in regulating soil-plant-human ecosystem functions. The biogeochemical behavior of Se and its environmental impact on the soil-plant-human system has received broad attention in the last decades. This review provides a comprehensive understanding of Se biogeochemistry in the soil-plant-human system. The speciation, transformation, bioavailability as well as the beneficial and hazardous effects of Se in the soil-plant-human system are summarized. Several important aspects in Se in the soil-plant-human system are detailed mentioned, including (1) strategies for biofortification in Se-deficient areas and phytoremediation of soil Se in seleniferous areas; (2) factors affecting Se uptake and transport by plants; (3) metabolic pathways of Se in the human body; (4) the interactions between Se and other trace elements in plant and animals, in particular, the detoxification of heavy metals by Se. Important research hotspots of Se biogeochemistry are outlined, including (1) the coupling of soil microbial activity and the Se biogeochemical cycle; (2) the molecular mechanism of Se metabolic in plants and animals; and (3) the application of Se isotopes as a biogeochemical tracer in research. This review provides up-to-date knowledge and guidelines on Se biogeochemistry research.
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Affiliation(s)
- Hui Yang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; Guizhou Academy of Tobacco Science, 550081 Guiyang, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xuefeng Yang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zengping Ning
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Sae Yun Kwon
- Division of Environmental Science & Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam Gu, Pohang 37673, South Korea
| | - Mi-Ling Li
- School of Marine Science and Policy, University of Delaware, Newark, DE 19716 USA
| | - Filip M G Tack
- Ghent University, Department of Green Chemistry and Technology, Ghent, Belgium
| | - Eilhann E Kwon
- Department of Environment, Energy and Geoinformatics, Sejong University, 98 Gunja-Dong, Guangjin-Gu, Seoul, Republic of Korea
| | - Jörg Rinklebe
- Department of Environment, Energy and Geoinformatics, Sejong University, 98 Gunja-Dong, Guangjin-Gu, Seoul, Republic of Korea; University of Wuppertal, School of Architecture and Civil Engineering, Institute of Foundation Engineering, Water and Waste Management, Laboratory of Soil and Groundwater Management, Pauluskirchstraße 7, 42285 Wuppertal, Germany
| | - Runsheng Yin
- State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.
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Xiong J, Wang H, Yao J, He Q, Ma J, Yang J, Liu C, Chen Y, Huangfu X, Liu H. A critical review on sulfur reduction of aqueous selenite: Mechanisms and applications. JOURNAL OF HAZARDOUS MATERIALS 2022; 422:126852. [PMID: 34399225 DOI: 10.1016/j.jhazmat.2021.126852] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 07/28/2021] [Accepted: 08/05/2021] [Indexed: 06/13/2023]
Abstract
Selenite, which is extremely toxic at high concentrations, can easily be enriched in natural aquatic environments due to human activities, which causes great harm to ecosystems. Sulfur reduction can effectively reduce soluble selenite in large quantities to nontoxic solid elemental selenium, which plays a significant role in controlling the toxicity and cycle of selenium. In view of the bright prospects of the sulfur reduction reaction of selenite, this review comprehensively summarizes the continuous development in the sulfidation of selenite. First, the geochemical characteristics of aqueous selenium in different sulfur systems involving species distribution and various phase types at Eh-pH conditions were summarized. Second, sulfur reductions of selenite with chemical sulfide in natural water environments, sulfur reductase and extracellular polymer substances containing thiol groups in sulfate-reducing bacteria have been reviewed to further understand the corresponding mechanisms, rates and influencing factors. Furthermore, applications of sulfur reduction of selenium, including removal of selenium, enrichment of selenium, synthesis of selenoproteins and prevention of leakage of selenium, were also summarized. Finally, this review identified future research needs for the sulfidation of selenite for environmental applications.
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Affiliation(s)
- Jiaming Xiong
- Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, College of Environment and Ecology, Chongqing University, Chongqing 400044, China
| | - Hainan Wang
- Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, College of Environment and Ecology, Chongqing University, Chongqing 400044, China
| | - Jinni Yao
- Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, College of Environment and Ecology, Chongqing University, Chongqing 400044, China
| | - Qiang He
- Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, College of Environment and Ecology, Chongqing University, Chongqing 400044, China
| | - Jun Ma
- State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090, China
| | - Jingjing Yang
- Center for Separation and Purification Materials & Technologies, Suzhou University of Science and Technology, Suzhou 215009, China
| | - Caihong Liu
- Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, College of Environment and Ecology, Chongqing University, Chongqing 400044, China
| | - Yao Chen
- Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, College of Environment and Ecology, Chongqing University, Chongqing 400044, China
| | - Xiaoliu Huangfu
- Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, College of Environment and Ecology, Chongqing University, Chongqing 400044, China.
| | - Hongxia Liu
- Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, College of Environment and Ecology, Chongqing University, Chongqing 400044, China.
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7
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Wang D, Rensing C, Zheng S. Microbial reduction and resistance to selenium: Mechanisms, applications and prospects. JOURNAL OF HAZARDOUS MATERIALS 2022; 421:126684. [PMID: 34339989 DOI: 10.1016/j.jhazmat.2021.126684] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 06/25/2021] [Accepted: 07/16/2021] [Indexed: 06/13/2023]
Abstract
Selenium is an essential trace element for humans, animals and microorganisms. Microbial transformations, in particular, selenium dissimilatory reduction and bioremediation applications have received increasing attention in recent years. This review focuses on multiple Se-reducing pathways under anaerobic and aerobic conditions, and the phylogenetic clustering of selenium reducing enzymes that are involved in these processes. It is emphasized that a selenium reductase may have more than one metabolic function, meanwhile, there are several Se(VI) and/or Se(IV) reduction pathways in a bacterial strain. It is noted that Se(IV)-reducing efficiency is inconsistent with Se(IV) resistance in bacteria. Moreover, we discussed the links of selenium transformations to biogeochemical cycling of other elements, roles of Se-reducing bacteria in soil, plant and digestion system, and the possibility of using functional genes involved in Se transformation as biomarker in different environments. In addition, we point out the gaps and perspectives both on Se transformation mechanisms and applications in terms of bioremediation, Se fortification or dietary supplementation.
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Affiliation(s)
- Dan Wang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China; College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, PR China
| | - Christopher Rensing
- Institute of Environmental Microbiology, College of Resources and Environment, Fujian Agriculture & Forestry University, Fuzhou, Fujian 350002, PR China.
| | - Shixue Zheng
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China.
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8
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Jugnia LB, Manno D, Vidales AG, Hrapovic S, Tartakovsky B. Selenite and selenate removal in a permeable flow-through bioelectrochemical barrier. JOURNAL OF HAZARDOUS MATERIALS 2021; 408:124431. [PMID: 33189466 DOI: 10.1016/j.jhazmat.2020.124431] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 10/21/2020] [Accepted: 10/28/2020] [Indexed: 06/11/2023]
Abstract
This study demonstrated the removal of selenite and selenate in flow-through permeable bioelectrochemical barriers (microbial electrolysis cells, MECs). The bioelectrochemical barriers consisted of cathode and anode electrode compartments filled with granular carbon or metallurgical coke. A voltage of 1.4 V was applied to the electrodes to enable the bioelectrochemical removal of selenium species. For comparison, a similarly designed permeable anaerobic biobarrier filled with granular carbon was operated without voltage. All biobarrier setups were fed with water containing up to 5,000 µg L-1 of either selenite or selenate and 70 mg L-1 of acetate as a source of organic carbon. Significant removal of selenite and selenate was observed in MEC experimental setups, reaching 99.5-99.8% over the course of the experiment, while in the anaerobic biobarrier the removal efficiency did not exceed 88%. By simultaneously operating several setups and changing operating parameters (selenium species, influent Se and acetate concentrations, etc.) we demonstrated enhanced removal of Se species under bioelectrochemical conditions.
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Affiliation(s)
- Louis-B Jugnia
- National Research Council Canada, 6100 Royalmount Avenue, Montreal, Quebec H4P 2R2, Canada.
| | - Dominic Manno
- National Research Council Canada, 6100 Royalmount Avenue, Montreal, Quebec H4P 2R2, Canada
| | - Abraham Gomez Vidales
- National Research Council Canada, 6100 Royalmount Avenue, Montreal, Quebec H4P 2R2, Canada
| | - Sabahudin Hrapovic
- National Research Council Canada, 6100 Royalmount Avenue, Montreal, Quebec H4P 2R2, Canada
| | - Boris Tartakovsky
- National Research Council Canada, 6100 Royalmount Avenue, Montreal, Quebec H4P 2R2, Canada
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9
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Song B, Tian Z, van der Weijden RD, Buisman CJN, Weijma J. High-rate biological selenate reduction in a sequencing batch reactor for recovery of hexagonal selenium. WATER RESEARCH 2021; 193:116855. [PMID: 33556693 DOI: 10.1016/j.watres.2021.116855] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 12/30/2020] [Accepted: 01/16/2021] [Indexed: 06/12/2023]
Abstract
Recovery of selenium (Se) from wastewater provides a solution for both securing Se supply and preventing Se pollution. Here, we developed a high-rate process for biological selenate reduction to elemental selenium. Distinctive from other studies, we aimed for a process with selenate as the main biological electron sink, with minimal formation of methane or sulfide. A sequencing batch reactor, fed with an influent containing 120 mgSe L-1 selenate and ethanol as electron donor and carbon source, was operated for 495 days. The high rates (419 ± 17 mgSe L-1 day-1) were recorded between day 446 and day 495 for a hydraulic retention time of 6 h. The maximum conversion efficiency of selenate amounted to 96% with a volumetric conversion rate of 444 mgSe L-1 day-1, which is 6 times higher than the rates reported in the literature thus far. At the end of the experiment, a highly enriched selenate reducing biomass had developed, with a specific activity of 856 ± 26 mgSe-1day-1gbiomass-1, which was nearly 1000-fold higher than that of the inoculum. No evidence was found for the formation of methane, sulfide, or volatile reduced selenium compounds like dimethyl-selenide or H2Se, revealing a high selectivity. Ethanol was incompletely oxidized to acetate. The produced elemental selenium partially accumulated in the reactor as pure (≥80% Se of the total mixture of biomass sludge flocs and flaky aggregates, and ~100% of the specific flaky aggregates) selenium black hexagonal needles, with cluster sizes between 20 and 200 µm. The new process may serve as the basis for a high-rate technology to remove and recover pure selenium from wastewater or process streams with high selectivity.
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Affiliation(s)
- B Song
- Department of Environmental Technology, Wageningen University and Research, P.O. Box 17; 6700 AA Wageningen, the Netherlands
| | - Z Tian
- Department of Environmental Technology, Wageningen University and Research, P.O. Box 17; 6700 AA Wageningen, the Netherlands
| | - R D van der Weijden
- Department of Environmental Technology, Wageningen University and Research, P.O. Box 17; 6700 AA Wageningen, the Netherlands
| | - C J N Buisman
- Department of Environmental Technology, Wageningen University and Research, P.O. Box 17; 6700 AA Wageningen, the Netherlands
| | - J Weijma
- Department of Environmental Technology, Wageningen University and Research, P.O. Box 17; 6700 AA Wageningen, the Netherlands.
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Abstract
'There's antimony, arsenic, aluminum, selenium, and hydrogen, and oxygen, and nitrogen and rhenium'-so begins 'The Elements' song (https://www.youtube.com/watch?v=AcS3NOQnsQM), whereby Tom Lehrer (Fig. 1) assiduously deconstructed the many painstaking decades of research effort by scores of scientists in assembling the Periodic Table as primarily based upon the atomic numbers of the elements. Lehrer instead opted for his imaginative rhyme, with its musical meter purloined from the patter song of Major General Stanley ("I am the Very Model of a Modern Major General') as in the Gilbert and Sullivan's operetta 'The Pirates of Penzance'. By some coincidence, however, three of the four named in the first stanza are Group 15 and 16 elements with which I have considerable microbiological research experience. Only one is missing (tellurium). Hence, by futzing with Lehrer's 'libretto' to suit my own needs for this issue of FEMS, I would pose the following introductory re-rearrangement: 'There's antimony, arsenic, selenium, tellurium, and cadmium, and chromium, and calcium and curium'. While this may (or may not) sit well with Mr Lehrer, who at the time of this writing is still living, I hope it does not cause further discomfiture to the collective eternal peace of Professor Dimitri Mendeleev, Sir William Schwenk Gilbert and Sir Arthur Sullivan. Nonetheless, I will use this preface to take departure for the primary subject of this manuscript, namely our efforts on selenium, which is where it all got started.
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Affiliation(s)
- Ronald S Oremland
- Emeritus Senior Scientist, United States Geological Survey, Menlo Park, CA 94025, USA
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11
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Wells M, Stolz JF. Microbial selenium metabolism: a brief history, biogeochemistry and ecophysiology. FEMS Microbiol Ecol 2020; 96:5921172. [DOI: 10.1093/femsec/fiaa209] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 10/08/2020] [Indexed: 01/02/2023] Open
Abstract
ABSTRACTSelenium is an essential trace element for organisms from all three domains of life. Microorganisms, in particular, mediate reductive transformations of selenium that govern the element's mobility and bioavailability in terrestrial and aquatic environments. Selenium metabolism is not just ubiquitous but an ancient feature of life likely extending back to the universal common ancestor of all cellular lineages. As with the sulfur biogeochemical cycle, reductive transformations of selenium serve two metabolic functions: assimilation into macromolecules and dissimilatory reduction during anaerobic respiration. This review begins with a historical overview of how research in both aspects of selenium metabolism has developed. We then provide an overview of the global selenium biogeochemical cycle, emphasizing the central role of microorganisms in the cycle. This serves as a basis for a robust discussion of current models for the evolution of the selenium biogeochemical cycle over geologic time, and how knowledge of the evolution and ecophysiology of selenium metabolism can enrich and refine these models. We conclude with a discussion of the ecophysiological function of selenium-respiring prokaryotes within the cycle, and the tantalizing possibility of oxidative selenium transformations during chemolithoautotrophic growth.
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Affiliation(s)
- Michael Wells
- Department of Biological Sciences, Duquesne University, Pittsburgh, PA 15282, USA
| | - John F Stolz
- Department of Biological Sciences, Duquesne University, Pittsburgh, PA 15282, USA
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12
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Shi LD, Lv PL, Niu ZF, Lai CY, Zhao HP. Why does sulfate inhibit selenate reduction: Molybdenum deprivation from Mo-dependent selenate reductase. WATER RESEARCH 2020; 178:115832. [PMID: 32335368 DOI: 10.1016/j.watres.2020.115832] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 04/07/2020] [Accepted: 04/13/2020] [Indexed: 06/11/2023]
Abstract
Selenium pollution has become an increasingly serious global concern. Methane-fed selenate reduction has proven to be of great interest for the bioremediation of selenate-contaminated waters even with the coexistence of nitrate and dissolved oxygen. However, it is unclear if the common concurrent sulfate anion affects selenate removal. To address this question, we first introduced selenate (SeO42-) as the sole influent electron acceptor in a CH4-fed membrane biofilm reactor (CH4-MBfR); then we added different concentrations of sulfate (SO42-). The initial selenate removal efficiency (∼90%) was decreased by 50% in the presence of 15.6 μM of sulfate and completely inhibited after loading with 171.9 μM of sulfate. 16S rRNA gene sequencing showed that the selenate-reducing bacteria decreased after the addition of sulfate. Metagenomic sequencing showed that the abundance of genes encoding molybdenum (Mo)-dependent selenate reductase reduced by >50% when exposed to high concentrations of sulfate. Furthermore, the decrease in the total genes encoding all Mo-oxidoreductases was much greater than that of the genes encoding molybdate transporters, suggesting that the inhibition of selenate reduction by sulfate was most likely via the direct competition with molybdate for the transport system, leading to a lack of available Mo for Mo-dependent selenate reductases and thus reducing their activities. This result was confirmed by a batch test wherein the supplementation of molybdate mitigated the sulfate effect. Overall, this study shed light on the underlying mechanism of sulfate inhibition on selenate reduction and laid the foundation for applying the technology to practical wastewaters.
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Affiliation(s)
- Ling-Dong Shi
- MOE Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Science, Zhejiang University, Hangzhou, 310058, China; Zhejiang Prov Key Lab Water Pollut Control & Envi, Zhejiang University, Hangzhou, Zhejiang, China
| | - Pan-Long Lv
- MOE Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Science, Zhejiang University, Hangzhou, 310058, China; Zhejiang Prov Key Lab Water Pollut Control & Envi, Zhejiang University, Hangzhou, Zhejiang, China
| | - Zi-Fan Niu
- MOE Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Science, Zhejiang University, Hangzhou, 310058, China; Zhejiang Prov Key Lab Water Pollut Control & Envi, Zhejiang University, Hangzhou, Zhejiang, China
| | - Chun-Yu Lai
- MOE Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Science, Zhejiang University, Hangzhou, 310058, China
| | - He-Ping Zhao
- MOE Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Science, Zhejiang University, Hangzhou, 310058, China; Zhejiang Prov Key Lab Water Pollut Control & Envi, Zhejiang University, Hangzhou, Zhejiang, China.
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13
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Fungal formation of selenium and tellurium nanoparticles. Appl Microbiol Biotechnol 2019; 103:7241-7259. [PMID: 31324941 PMCID: PMC6691031 DOI: 10.1007/s00253-019-09995-6] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 06/17/2019] [Accepted: 06/17/2019] [Indexed: 11/24/2022]
Abstract
The fungi Aureobasidium pullulans, Mortierella humilis, Trichoderma harzianum and Phoma glomerata were used to investigate the formation of selenium- and tellurium-containing nanoparticles during growth on selenium- and tellurium-containing media. Most organisms were able to grow on both selenium- and tellurium-containing media at concentrations of 1 mM resulting in extensive precipitation of elemental selenium and tellurium on fungal surfaces as observed by the red and black colour changes. Red or black deposits were confirmed as elemental selenium and tellurium, respectively. Selenium oxide and tellurium oxide were also found after growth of Trichoderma harzianum with 1 mM selenite and tellurite as well as the formation of elemental selenium and tellurium. The hyphal matrix provided nucleation sites for metalloid deposition with extracellular protein and extracellular polymeric substances localizing the resultant Se or Te nanoparticles. These findings are relevant to remedial treatments for selenium and tellurium and to novel approaches for selenium and tellurium biorecovery.
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14
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LeBlanc KL, Kumkrong P, Mercier PHJ, Mester Z. Selenium analysis in waters. Part 2: Speciation methods. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 640-641:1635-1651. [PMID: 29935780 DOI: 10.1016/j.scitotenv.2018.05.394] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 05/25/2018] [Accepted: 05/31/2018] [Indexed: 06/08/2023]
Abstract
In aquatic ecosystems, there is often no correlation between the total concentration of selenium present in the water column and the toxic effects observed in that environment. This is due, in part, to the variation in the bioavailability of different selenium species to organisms at the base of the aquatic food chain. The first part of this review (Kumkrong et al., 2018) discusses regulatory framework and standard methodologies for selenium analysis in waters. In this second article, we are reviewing the state of speciation analysis and importance of speciation data for decision makers in industry and regulators. We look in detail at fractionation methods for speciation, including the popular selective sequential hydride generation. We examine advantages and limitations of these methods, in terms of achievable detection limits and interferences from other matrix species, as well as the potential to over- or under-estimate operationally-defined fractions based on the various conversion steps involved in fractionation processes. Additionally, we discuss methods of discrete speciation (through separation methods), their importance in analyzing individual selenium species, difficulties associated with their implementation, as well as ways to overcome these difficulties. We also provide a brief overview of biological treatment methods for the remediation of selenium-contaminated waters. We discuss the importance of selenium speciation in the application of these methods and their potential to actually increase the bioavailability of selenium despite decreasing its total waterborne concentration.
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Affiliation(s)
- Kelly L LeBlanc
- National Research Council Canada, 1200 Montreal Road, Ottawa, Ontario, Canada.
| | - Paramee Kumkrong
- National Research Council Canada, 1200 Montreal Road, Ottawa, Ontario, Canada
| | - Patrick H J Mercier
- National Research Council Canada, 1200 Montreal Road, Ottawa, Ontario, Canada
| | - Zoltán Mester
- National Research Council Canada, 1200 Montreal Road, Ottawa, Ontario, Canada
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15
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Bao P, Li GX, Sun GX, Xu YY, Meharg AA, Zhu YG. The role of sulfate-reducing prokaryotes in the coupling of element biogeochemical cycling. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 613-614:398-408. [PMID: 28918271 DOI: 10.1016/j.scitotenv.2017.09.062] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 09/07/2017] [Accepted: 09/07/2017] [Indexed: 06/07/2023]
Abstract
Sulfate-reducing prokaryotes (SRP) represent a diverse group of heterotrophic and autotrophic microorganisms that are ubiquitous in anoxic habitats. In addition to their important role in both sulfur and carbon cycles, SRP are important biotic and abiotic regulators of a variety of sulfur-driven coupled biogeochemical cycling of elements, including: oxygen, nitrogen, chlorine, bromine, iodine and metal(loid)s. SRP gain energy form most of the coupling of element transformation. Once sulfate-reducing conditions are established, sulfide precipitation becomes the predominant abiotic mechanism of metal(loid)s transformation, followed by co-precipitation between metal(loid)s. Anthropogenic contamination, since the industrial revolution, has dramatically disturbed sulfur-driven biogeochemical cycling; making sulfur coupled elements transformation complicated and unpredictable. We hypothesise that sulfur might be detoxication agent for the organic and inorganic toxic compounds, through the metabolic activity of SRP. This review synthesizes the recent advances in the role of SRP in coupled biogeochemical cycling of diverse elements.
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Affiliation(s)
- Peng Bao
- Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, PR China; Ningbo Urban Environment Observation and Station, Chinese Academy of Sciences, Ningbo 315800, PR China
| | - Guo-Xiang Li
- Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, PR China; Ningbo Urban Environment Observation and Station, Chinese Academy of Sciences, Ningbo 315800, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Guo-Xin Sun
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100086, PR China
| | - Yao-Yang Xu
- Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, PR China; Ningbo Urban Environment Observation and Station, Chinese Academy of Sciences, Ningbo 315800, PR China
| | - Andrew A Meharg
- Institute of Global Food Security, Queen's University Belfast, David Keir Building, Stranmillis Road, Belfast BT9 5AG, United Kingdom
| | - Yong-Guan Zhu
- Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, PR China; State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100086, PR China.
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16
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Fakra SC, Luef B, Castelle CJ, Mullin SW, Williams KH, Marcus MA, Schichnes D, Banfield JF. Correlative Cryogenic Spectromicroscopy to Investigate Selenium Bioreduction Products. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:503-512. [PMID: 26371540 DOI: 10.1021/acs.est.5b01409] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Accurate mapping of the composition and structure of minerals and associated biological materials is critical in geomicrobiology and environmental research. Here, we have developed an apparatus that allows the correlation of cryogenic transmission electron microscopy (cryo-TEM) and synchrotron hard X-ray microprobe (SHXM) data sets to precisely determine the distribution, valence state, and structure of selenium in biofilms sampled from a contaminated aquifer near Rifle, CO. Results were replicated in the laboratory via anaerobic selenate-reducing enrichment cultures. 16S rRNA analyses of field-derived biofilm indicated the dominance of Betaproteobacteria from the Comamonadaceae family and uncultivated members of the Simplicispira genus. The major product in field and culture-derived biofilms is ∼25-300 nm red amorphous Se0 aggregates of colloidal nanoparticles. Correlative analyses of the cultures provided direct evidence for the microbial dissimilatory reduction of Se(VI) to Se(IV) to Se0. Extended X-ray absorption fine-structure spectroscopy showed red amorphous Se0 with a first shell Se-Se interatomic distance of 2.339 ± 0.003 Å. Complementary scanning transmission X-ray microscopy revealed that these aggregates are strongly associated with a protein-rich biofilm matrix. These findings have important implications for predicting the stability and mobility of Se bioremediation products and understanding of Se biogeochemical cycling. The approach, involving the correlation of cryo-SHXM and cryo-TEM data sets from the same specimen area, is broadly applicable to biological and environmental samples.
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Affiliation(s)
- Sirine C Fakra
- Department of Earth and Planetary Science and ‡Department of Plant & Microbial Biology, University of California , Berkeley, California 94720, United States
- Advanced Light Source and ∥Earth Sciences Division, Lawrence Berkeley National Lab , Berkeley, California 94720, United States
| | - Birgit Luef
- Department of Earth and Planetary Science and ‡Department of Plant & Microbial Biology, University of California , Berkeley, California 94720, United States
- Advanced Light Source and ∥Earth Sciences Division, Lawrence Berkeley National Lab , Berkeley, California 94720, United States
| | - Cindy J Castelle
- Department of Earth and Planetary Science and ‡Department of Plant & Microbial Biology, University of California , Berkeley, California 94720, United States
- Advanced Light Source and ∥Earth Sciences Division, Lawrence Berkeley National Lab , Berkeley, California 94720, United States
| | - Sean W Mullin
- Department of Earth and Planetary Science and ‡Department of Plant & Microbial Biology, University of California , Berkeley, California 94720, United States
- Advanced Light Source and ∥Earth Sciences Division, Lawrence Berkeley National Lab , Berkeley, California 94720, United States
| | - Kenneth H Williams
- Department of Earth and Planetary Science and ‡Department of Plant & Microbial Biology, University of California , Berkeley, California 94720, United States
- Advanced Light Source and ∥Earth Sciences Division, Lawrence Berkeley National Lab , Berkeley, California 94720, United States
| | - Matthew A Marcus
- Department of Earth and Planetary Science and ‡Department of Plant & Microbial Biology, University of California , Berkeley, California 94720, United States
- Advanced Light Source and ∥Earth Sciences Division, Lawrence Berkeley National Lab , Berkeley, California 94720, United States
| | - Denise Schichnes
- Department of Earth and Planetary Science and ‡Department of Plant & Microbial Biology, University of California , Berkeley, California 94720, United States
- Advanced Light Source and ∥Earth Sciences Division, Lawrence Berkeley National Lab , Berkeley, California 94720, United States
| | - Jillian F Banfield
- Department of Earth and Planetary Science and ‡Department of Plant & Microbial Biology, University of California , Berkeley, California 94720, United States
- Advanced Light Source and ∥Earth Sciences Division, Lawrence Berkeley National Lab , Berkeley, California 94720, United States
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17
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Microbial Transformations of Selenium Species of Relevance to Bioremediation. Appl Environ Microbiol 2016; 82:4848-59. [PMID: 27260359 DOI: 10.1128/aem.00877-16] [Citation(s) in RCA: 117] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Selenium species, particularly the oxyanions selenite (SeO3 (2-)) and selenate (SeO4 (2-)), are significant pollutants in the environment that leach from rocks and are released by anthropogenic activities. Selenium is also an essential micronutrient for organisms across the tree of life, including microorganisms and human beings, particularly because of its presence in the 21st genetically encoded amino acid, selenocysteine. Environmental microorganisms are known to be capable of a range of transformations of selenium species, including reduction, methylation, oxidation, and demethylation. Assimilatory reduction of selenium species is necessary for the synthesis of selenoproteins. Dissimilatory reduction of selenate is known to support the anaerobic respiration of a number of microorganisms, and the dissimilatory reduction of soluble selenate and selenite to nanoparticulate elemental selenium greatly reduces the toxicity and bioavailability of selenium and has a major role in bioremediation and potentially in the production of selenium nanospheres for technological applications. Also, microbial methylation after reduction of Se oxyanions is another potentially effective detoxification process if limitations with low reaction rates and capture of the volatile methylated selenium species can be overcome. This review discusses microbial transformations of different forms of Se in an environmental context, with special emphasis on bioremediation of Se pollution.
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18
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Tan LC, Nancharaiah YV, van Hullebusch ED, Lens PNL. Selenium: environmental significance, pollution, and biological treatment technologies. Biotechnol Adv 2016; 34:886-907. [PMID: 27235190 DOI: 10.1016/j.biotechadv.2016.05.005] [Citation(s) in RCA: 210] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2015] [Revised: 04/26/2016] [Accepted: 05/21/2016] [Indexed: 10/21/2022]
Abstract
Selenium is an essential trace element needed for all living organisms. Despite its essentiality, selenium is a potential toxic element to natural ecosystems due to its bioaccumulation potential. Though selenium is found naturally in the earth's crust, especially in carbonate rocks and volcanic and sedimentary soils, about 40% of the selenium emissions to atmospheric and aquatic environments are caused by various industrial activities such as mining-related operations. In recent years, advances in water quality and pollution monitoring have shown that selenium is a contaminant of potential environmental concern. This has practical implications on industry to achieve the stringent selenium regulatory discharge limit of 5μgSeL(-1) for selenium containing wastewaters set by the United States Environmental Protection Agency. Over the last few decades, various technologies have been developed for the treatment of selenium-containing wastewaters. Biological selenium reduction has emerged as the leading technology for removing selenium from wastewaters since it offers a cheaper alternative compared to physico-chemical treatments and is suitable for treating dilute and variable selenium-laden wastewaters. Moreover, biological treatment has the advantage of forming elemental selenium nanospheres which exhibit unique optical and spectral properties for various industrial applications, i.e. medical, electrical, and manufacturing processes. However, despite the advances in biotechnology employing selenium reduction, there are still several challenges, particularly in achieving stringent discharge limits, the long-term stability of biogenic selenium and predicting the fate of bioreduced selenium in the environment. This review highlights the significance of selenium in the environment, health, and industry and biotechnological advances made in the treatment of selenium contaminated wastewaters. The challenges and future perspectives are overviewed considering recent biotechnological advances in the management of these selenium-laden wastewaters.
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Affiliation(s)
- Lea Chua Tan
- UNESCO-IHE Institute for Water Education, Westvest 7, 2611 AX Delft, The Netherlands.
| | - Yarlagadda V Nancharaiah
- Biofouling and Biofilm Process Section, Water and Steam Chemistry Division, Bhabha Atomic Research Centre Kalpakkam, 603102 Tamil Nadu, India.
| | - Eric D van Hullebusch
- Université Paris-Est, Laboratoire Géomatériaux et Environnement (EA 4508), UPEM, 77454 Marne-la-Vallée, France.
| | - Piet N L Lens
- UNESCO-IHE Institute for Water Education, Westvest 7, 2611 AX Delft, The Netherlands; Department of Chemistry and Bioengineering, Tampere University of Technology, P.O-Box 541, Tampere, Finland.
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19
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Hsiang HI, Chiang CY, Hsu WH, Chen WS, Chang JE. Leaching and re-synthesis of CIGS nanocrystallites from spent CIGS targets. ADV POWDER TECHNOL 2016. [DOI: 10.1016/j.apt.2016.02.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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20
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Ontiveros-Valencia A, Penton CR, Krajmalnik-Brown R, Rittmann BE. Hydrogen-fed biofilm reactors reducing selenate and sulfate: Community structure and capture of elemental selenium within the biofilm. Biotechnol Bioeng 2016; 113:1736-44. [DOI: 10.1002/bit.25945] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 01/16/2016] [Accepted: 01/20/2016] [Indexed: 11/07/2022]
Affiliation(s)
- Aura Ontiveros-Valencia
- Swette Center for Environmental Biotechnology; Biodesign Institute, Arizona State University; 1001 South McAllister Ave. Tempe Arizona 85287-5701
| | | | - Rosa Krajmalnik-Brown
- Swette Center for Environmental Biotechnology; Biodesign Institute, Arizona State University; 1001 South McAllister Ave. Tempe Arizona 85287-5701
- School of Sustainable Engineering and the Built Environment; Arizona State University; Tempe Arizona
| | - Bruce E. Rittmann
- Swette Center for Environmental Biotechnology; Biodesign Institute, Arizona State University; 1001 South McAllister Ave. Tempe Arizona 85287-5701
- School of Sustainable Engineering and the Built Environment; Arizona State University; Tempe Arizona
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21
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Mal J, Nancharaiah YV, van Hullebusch ED, Lens PNL. Metal chalcogenide quantum dots: biotechnological synthesis and applications. RSC Adv 2016. [DOI: 10.1039/c6ra08447h] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Metal chalcogenide (metal sulfide, selenide and telluride) quantum dots (QDs) have attracted considerable attention due to their quantum confinement and size-dependent photoemission characteristics.
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Affiliation(s)
- J. Mal
- UNESCO-IHE
- Delft
- The Netherlands
- Biofouling and Biofilm Process Section
- Water and Steam Chemistry Division
| | - Y. V. Nancharaiah
- UNESCO-IHE
- Delft
- The Netherlands
- Université Paris-Est
- Laboratoire Géomatériaux et Environnement (LGE)
| | - E. D. van Hullebusch
- Biofouling and Biofilm Process Section
- Water and Steam Chemistry Division
- Bhabha Atomic Research Centre
- Kalpakkam-603102
- India
| | - P. N. L. Lens
- UNESCO-IHE
- Delft
- The Netherlands
- Department of Chemistry and Bioengineering
- Tampere University of Technology
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22
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A Post-Genomic View of the Ecophysiology, Catabolism and Biotechnological Relevance of Sulphate-Reducing Prokaryotes. Adv Microb Physiol 2015. [PMID: 26210106 DOI: 10.1016/bs.ampbs.2015.05.002] [Citation(s) in RCA: 173] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Dissimilatory sulphate reduction is the unifying and defining trait of sulphate-reducing prokaryotes (SRP). In their predominant habitats, sulphate-rich marine sediments, SRP have long been recognized to be major players in the carbon and sulphur cycles. Other, more recently appreciated, ecophysiological roles include activity in the deep biosphere, symbiotic relations, syntrophic associations, human microbiome/health and long-distance electron transfer. SRP include a high diversity of organisms, with large nutritional versatility and broad metabolic capacities, including anaerobic degradation of aromatic compounds and hydrocarbons. Elucidation of novel catabolic capacities as well as progress in the understanding of metabolic and regulatory networks, energy metabolism, evolutionary processes and adaptation to changing environmental conditions has greatly benefited from genomics, functional OMICS approaches and advances in genetic accessibility and biochemical studies. Important biotechnological roles of SRP range from (i) wastewater and off gas treatment, (ii) bioremediation of metals and hydrocarbons and (iii) bioelectrochemistry, to undesired impacts such as (iv) souring in oil reservoirs and other environments, and (v) corrosion of iron and concrete. Here we review recent advances in our understanding of SRPs focusing mainly on works published after 2000. The wealth of publications in this period, covering many diverse areas, is a testimony to the large environmental, biogeochemical and technological relevance of these organisms and how much the field has progressed in these years, although many important questions and applications remain to be explored.
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23
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Carlson HK, Stoeva MK, Justice NB, Sczesnak A, Mullan MR, Mosqueda LA, Kuehl JV, Deutschbauer AM, Arkin AP, Coates JD. Monofluorophosphate is a selective inhibitor of respiratory sulfate-reducing microorganisms. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:3727-3736. [PMID: 25698072 DOI: 10.1021/es505843z] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Despite the environmental and economic cost of microbial sulfidogenesis in industrial operations, few compounds are known as selective inhibitors of respiratory sulfate reducing microorganisms (SRM), and no study has systematically and quantitatively evaluated the selectivity and potency of SRM inhibitors. Using general, high-throughput assays to quantitatively evaluate inhibitor potency and selectivity in a model sulfate-reducing microbial ecosystem as well as inhibitor specificity for the sulfate reduction pathway in a model SRM, we screened a panel of inorganic oxyanions. We identified several SRM selective inhibitors including selenate, selenite, tellurate, tellurite, nitrate, nitrite, perchlorate, chlorate, monofluorophosphate, vanadate, molydate, and tungstate. Monofluorophosphate (MFP) was not known previously as a selective SRM inhibitor, but has promising characteristics including low toxicity to eukaryotic organisms, high stability at circumneutral pH, utility as an abiotic corrosion inhibitor, and low cost. MFP remains a potent inhibitor of SRM growing by fermentation, and MFP is tolerated by nitrate and perchlorate reducing microorganisms. For SRM inhibition, MFP is synergistic with nitrite and chlorite, and could enhance the efficacy of nitrate or perchlorate treatments. Finally, MFP inhibition is multifaceted. Both inhibition of the central sulfate reduction pathway and release of cytoplasmic fluoride ion are implicated in the mechanism of MFP toxicity.
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Affiliation(s)
- Hans K Carlson
- †Energy Biosciences Institute, University of California-Berkeley, Berkeley, California 94720, United States
| | - Magdalena K Stoeva
- ∥Department of Plant and Microbial Biology, University of California-Berkeley, Berkeley, California 94720, United States
| | - Nicholas B Justice
- ‡Physical Biosciences Division, Lawrence Berkeley National Lab, Berkeley, California 94720, United States
| | - Andrew Sczesnak
- ⊥Department of Bioengineering, University of California-Berkeley, Berkeley, California 94720, United States
| | - Mark R Mullan
- †Energy Biosciences Institute, University of California-Berkeley, Berkeley, California 94720, United States
| | - Lorraine A Mosqueda
- †Energy Biosciences Institute, University of California-Berkeley, Berkeley, California 94720, United States
| | - Jennifer V Kuehl
- ‡Physical Biosciences Division, Lawrence Berkeley National Lab, Berkeley, California 94720, United States
| | - Adam M Deutschbauer
- ‡Physical Biosciences Division, Lawrence Berkeley National Lab, Berkeley, California 94720, United States
| | - Adam P Arkin
- ‡Physical Biosciences Division, Lawrence Berkeley National Lab, Berkeley, California 94720, United States
- ⊥Department of Bioengineering, University of California-Berkeley, Berkeley, California 94720, United States
| | - John D Coates
- †Energy Biosciences Institute, University of California-Berkeley, Berkeley, California 94720, United States
- §Earth Sciences Division, Lawrence Berkeley National Lab, Berkeley, California 94720, United States
- ∥Department of Plant and Microbial Biology, University of California-Berkeley, Berkeley, California 94720, United States
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24
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Abstract
In nature, selenium is actively cycled between oxic and anoxic habitats, and this cycle plays an important role in carbon and nitrogen mineralization through bacterial anaerobic respiration. Selenium-respiring bacteria (SeRB) are found in geographically diverse, pristine or contaminated environments and play a pivotal role in the selenium cycle. Unlike its structural analogues oxygen and sulfur, the chalcogen selenium and its microbial cycling have received much less attention by the scientific community. This review focuses on microorganisms that use selenate and selenite as terminal electron acceptors, in parallel to the well-studied sulfate-reducing bacteria. It overviews the significant advancements made in recent years on the role of SeRB in the biological selenium cycle and their ecological role, phylogenetic characterization, and metabolism, as well as selenium biomineralization mechanisms and environmental biotechnological applications.
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Affiliation(s)
- Y V Nancharaiah
- Environmental Engineering and Water Technology Department, UNESCO-IHE Institute for Water Education, Delft, The Netherlands Biofouling and Biofilm Processes Section, Water and Steam Chemistry Division, Bhabha Atomic Research Centre, Kalpakkam, Tamil Nadu, India
| | - P N L Lens
- Environmental Engineering and Water Technology Department, UNESCO-IHE Institute for Water Education, Delft, The Netherlands
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25
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Investigating the Effects of Se Solid Phase Substitution in Jarosite Minerals Influenced by Bacterial Reductive Dissolution. MINERALS 2014. [DOI: 10.3390/min4010017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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26
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Suzuki Y, Sakama Y, Saiki H, Kitamura A, Yoshikawa H, Tanaka K. Immobilization of selenium by biofilm ofShewanella putrefacienswith and without Fe(III)-citrate complex. J NUCL SCI TECHNOL 2013. [DOI: 10.1080/00223131.2013.851041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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27
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Hageman SPW, van der Weijden RD, Weijma J, Buisman CJN. Microbiological selenate to selenite conversion for selenium removal. WATER RESEARCH 2013; 47:2118-2128. [PMID: 23485421 DOI: 10.1016/j.watres.2013.01.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 12/25/2012] [Accepted: 01/06/2013] [Indexed: 06/01/2023]
Abstract
Removal of the toxic selenium compounds selenite and selenate from waste water before discharge is becoming increasingly imperative in industrialized countries. Bacteria can reduce selenate to selenite, but also further to elemental selenium, selenide or organic selenium. In this paper, we aim to exclusively bio-reduce selenate to selenite in an open high-rate bioreactor. This conversion could be part of a two-stage process in which the selenite is subsequently reduced by chemical means under optimal conditions to produce a biomass-free selenium product. In the process, yield and reduction rate of biological selenate to selenite should be maximized, while formation of elemental selenium, selenide and organic selenium compounds should be avoided. Fed-batch experiments with a liquid volume of 0.25-0.75 L at different temperatures 20-30-40-50 °C, pH settings 6-7-8-9, initial biomass concentration of 1 or 5 g wet weight granular Eerbeek sludge and various lactic acid concentrations were performed to determine their effect on the biological conversion of selenate to selenite. Furthermore, the effect on selenite losses by further biological reduction or, if present, chemical reduction was investigated as well. Optimal selenate reduction to selenite was found at 30 °C and pH 6 or 7 or 8 with 25 mM selenate and 13.75 mM lactic acid in the influent, with a selenite yield of 79-95%. In all the other conditions, less selenate was reduced to selenite. Also a 5 times higher electron donor concentration resulted in less selenite production, with only 22% of the selenate converted to selenite. The high yield and the high biological reduction rate of at least 741 mg Se/g initial VSS/day detected in the 1 g initial biomass experiment implicate that biological selenate conversion to selenite is a feasible process.
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Affiliation(s)
- Simon P W Hageman
- Sub-department of Environmental Technology, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands.
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28
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Truong HYT, Chen YW, Belzile N. Effect of sulfide, selenite and mercuric mercury on the growth and methylation capacity of the sulfate reducing bacterium Desulfovibrio desulfuricans. THE SCIENCE OF THE TOTAL ENVIRONMENT 2013; 449:373-84. [PMID: 23454698 DOI: 10.1016/j.scitotenv.2013.01.054] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Revised: 01/14/2013] [Accepted: 01/15/2013] [Indexed: 05/09/2023]
Abstract
Cultures of the sulfate reducing bacteria Desulfovibrio desulfuricans were grown under anoxic conditions to study the effect of added sulfide, selenite and mercuric ions. A chemical trap consisting in a CuSO4 solution was used to control the poisoning effect induced by the bacterial production of hydrogen sulfide via the precipitation of CuS. Following the addition of Hg(2+), the formation of methylmercury (MeHg) was correlated to bacterial proliferation with most of MeHg found in the culture medium. A large fraction (50-80%) of added Hg(2+) to a culture ended up in a solid phase (Hg(0) and likely HgS) limiting its bioavailability to cells with elemental Hg representing ~40% of the solid. Following the addition of selenite, a small fraction was converted into Se(0) inside the cells and, even though the conversion to this selenium species increased with the increase of added selenite, it never reached more than 49% of the added amount. The formation of volatile dimethylselenide is suggested as another detoxification mechanism. In cultures containing both added selenite and mercuric ions, elemental forms of the two compounds were still produced and the increase of selenium in the residual fraction of the culture suggests the formation of mercuric selenite limiting the bioavailability of both elements to cells.
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Affiliation(s)
- Hoang-Yen T Truong
- Department of Biology, Laurentian University, Sudbury, Ontario, Canada P3E 2C6
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29
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Bao P, Huang H, Hu ZY, Häggblom M, Zhu YG. Impact of temperature, CO2
fixation and nitrate reduction on selenium reduction, by a paddy soil Clostridium
strain. J Appl Microbiol 2013. [DOI: 10.1111/jam.12084] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- P. Bao
- State Key Lab of Urban and Regional Ecology; Research Center for Eco-Environmental Sciences; Chinese Academy of Sciences; Beijing China
| | - H. Huang
- State Key Lab of Urban and Regional Ecology; Research Center for Eco-Environmental Sciences; Chinese Academy of Sciences; Beijing China
| | - Z.-Y. Hu
- College of Resources and Environment; Graduate University of Chinese Academy of Sciences; Beijing China
| | - M.M. Häggblom
- Rutgers University; Department of Biochemistry and Microbiology; School of Environmental and Biological Sciences; New Brunswick NJ USA
| | - Y.-G. Zhu
- State Key Lab of Urban and Regional Ecology; Research Center for Eco-Environmental Sciences; Chinese Academy of Sciences; Beijing China
- Key Lab of Urban Environment and Health; Institute of Urban Environment, Chinese Academy of Sciences; Xiamen China
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30
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Gibson BD, Blowes DW, Lindsay MBJ, Ptacek CJ. Mechanistic investigations of Se(VI) treatment in anoxic groundwater using granular iron and organic carbon: an EXAFS study. JOURNAL OF HAZARDOUS MATERIALS 2012; 241-242:92-100. [PMID: 23040313 DOI: 10.1016/j.jhazmat.2012.09.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Revised: 09/10/2012] [Accepted: 09/10/2012] [Indexed: 06/01/2023]
Abstract
The removal of aqueous Se(VI) from a simulated groundwater by granular iron (GI), organic carbon (OC), and a mixture of these reactive materials (GI-OC) was evaluated in laboratory batch experiments. The experiments were performed under anoxic conditions to simulate subsurface treatment. A total reaction time of 120 h (5 d) was chosen to investigate the rapid changes in speciation occurring over reaction times that are reasonable for permeable reactive barrier (PRB) systems. After 120 h, concentrations of Se decreased by >90% in the GI system, 15% in the OC system and 35% in the GI-OC mixture. Analysis of the materials after contact with Se using synchrotron-radiation based X-ray absorption spectroscopy (XAS) indicated the presence of Se(IV) and Se(0) on the margins of GI grains after 6h with evidence of SeO and SeSe bonding, whereas Se(VI) was not observed. After 72 h, Se(0) was the only form of Se present in the GI experiments. In the OC batches, the XAS analysis indicated binding consistent with sorption of aqueous Se(VI) onto the OC with only minor reduction to Se(IV) and Se(0) after 120 h. Selenium XAS spectra collected for the GI-OC mixture were consistent with spectra for Se(IV) and Se(0) on both the margins of GI grains and OC particles, suggesting that the presence of dissolved Fe may have mediated the reduction of sorbed Se(VI). The results suggest that the application of granular Fe is effective at inducing aqueous Se removal in anoxic conditions through reductive precipitation processes.
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Affiliation(s)
- Blair D Gibson
- Department of Earth and Environmental Sciences, University of Waterloo, 200 University Ave. W., Waterloo, ON N2L 3G1, Canada.
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31
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Dhanjal S, Cameotra SS. Aerobic biogenesis of selenium nanospheres by Bacillus cereus isolated from coalmine soil. Microb Cell Fact 2010; 9:52. [PMID: 20602763 PMCID: PMC2909957 DOI: 10.1186/1475-2859-9-52] [Citation(s) in RCA: 164] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2010] [Accepted: 07/05/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Microorganisms that are exposed to pollutants in the environment, such as metals/metalloids, have a remarkable ability to fight the metal stress by various mechanisms. These metal-microbe interactions have already found an important role in biotechnological applications. It is only recently that microorganisms have been explored as potential biofactories for synthesis of metal/metalloid nanoparticles. Biosynthesis of selenium (Se 0) nanospheres in aerobic conditions by a bacterial strain isolated from the coalmine soil is reported in the present study. RESULTS The strain CM100B, identified as Bacillus cereus by morphological, biochemical and 16S rRNA gene sequencing [GenBank:GU551935.1] was studied for its ability to generate selenium nanoparticles (SNs) by transformation of toxic selenite (SeO3(2-)) anions into red elemental selenium (Se 0) under aerobic conditions. Also, the ability of the strain to tolerate high levels of toxic selenite ions was studied by challenging the microbe with different concentrations of sodium selenite (0.5 mM-10 mM). ESEM, AFM and SEM studies revealed the spherical Se 0 nanospheres adhering to bacterial biomass as well as present as free particles. The TEM microscopy showed the accumulation of spherical nanostructures as intracellular and extracellular deposits. The deposits were identified as element selenium by EDX analysis. This is also indicated by the red coloration of the culture broth that starts within 2-3 h of exposure to selenite oxyions. Selenium nanoparticles (SNs) were further characterized by UV-Visible spectroscopy, TEM and zeta potential measurement. The size of nanospheres was in the range of 150-200 nm with high negative charge of -46.86 mV. CONCLUSIONS This bacterial isolate has the potential to be used as a bionanofactory for the synthesis of stable, nearly monodisperse Se 0 nanoparticles as well as for detoxification of the toxic selenite anions in the environment. A hypothetical mechanism for the biogenesis of selenium nanoparticles (SNs) involving membrane associated reductase enzyme(s) that reduces selenite (SeO3(2-)) to Se 0 through electron shuttle enzymatic metal reduction process has been proposed.
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Affiliation(s)
- Soniya Dhanjal
- Institute of Microbial Technology, Sector 39-A, Chandigarh 160036, India
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32
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Oremland RS, Hollibaugh JT, Maest AS, Presser TS, Miller LG, Culbertson CW. Selenate reduction to elemental selenium by anaerobic bacteria in sediments and culture: biogeochemical significance of a novel, sulfate-independent respiration. Appl Environ Microbiol 2010; 55:2333-43. [PMID: 16348014 PMCID: PMC203077 DOI: 10.1128/aem.55.9.2333-2343.1989] [Citation(s) in RCA: 260] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Interstitial water profiles of SeO(4), SeO(3), SO(4), and Cl in anoxic sediments indicated removal of the seleno-oxyanions by a near-surface process unrelated to sulfate reduction. In sediment slurry experiments, a complete reductive removal of SeO(4) occurred under anaerobic conditions, was more rapid with H(2) or acetate, and was inhibited by O(2), NO(3), MnO(2), or autoclaving but not by SO(4) or FeOOH. Oxidation of acetate in sediments could be coupled to selenate but not to molybdate. Reduction of selenate to elemental selenium was determined to be the mechanism for loss from solution. Selenate reduction was inhibited by tungstate and chromate but not by molybdate. A small quantity of the elemental selenium precipitated into sediments from solution could be resolublized by oxidation with either nitrate or FeOOH, but not with MnO(2). A bacterium isolated from estuarine sediments demonstrated selenate-dependent growth on acetate, forming elemental selenium and carbon dioxide as respiratory end products. These results indicate that dissimilatory selenate reduction to elemental selenium is the major sink for selenium oxyanions in anoxic sediments. In addition, they suggest application as a treatment process for removing selenium oxyanions from wastewaters and also offer an explanation for the presence of selenite in oxic waters.
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Affiliation(s)
- R S Oremland
- Water Resources Division, U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025, and Tiburon Center, San Francisco State University, Tiburon, California 94920
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33
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Lenz M, Lens PNL. The essential toxin: the changing perception of selenium in environmental sciences. THE SCIENCE OF THE TOTAL ENVIRONMENT 2009; 407:3620-33. [PMID: 18817944 DOI: 10.1016/j.scitotenv.2008.07.056] [Citation(s) in RCA: 200] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2008] [Revised: 07/17/2008] [Accepted: 07/30/2008] [Indexed: 05/12/2023]
Abstract
During the last decades, the perception of selenium has undergone substantial changes. While its toxic effects were recognized causing hair and hoof loss in animals during the 1930s, its essential role in microbial, animal and human metabolism has been recognized later, i.e. with the discovery of selenium deficiency causing "white muscle disease" in feedstock in the 1950s. Nowadays, the positive effect of systematic selenium supplementation is discussed in manifold topics such as cancer or diabetes prevention and avian influenza susceptibility. Treatment of selenium containing waste streams poses a notable challenge to environmental engineers, and to date no ultimate solution has been found for e.g. the selenium contamination in agricultural areas of the western USA. For the future, selenium contamination carries an imminent danger, if the increasing energy demand is covered by fossil fuel combustion, which will lead to major selenium emission and toxicity. This review presents current knowledge of selenium's role in environmental sciences and outlines potentially feasible treatment options targeting a variety of selenium contaminated waste streams.
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Affiliation(s)
- Markus Lenz
- Sub-Department of Environmental Technology, Wageningen University, Bomenweg 2, 6700 EV Wageningen, The Netherlands
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34
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Chen YW, Truong HYT, Belzile N. Abiotic formation of elemental selenium and role of iron oxide surfaces. CHEMOSPHERE 2009; 74:1079-1084. [PMID: 19062070 DOI: 10.1016/j.chemosphere.2008.10.043] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Revised: 10/24/2008] [Accepted: 10/27/2008] [Indexed: 05/27/2023]
Abstract
The possible abiotic reduction of selenite to form elemental Se was studied under controlled conditions in the presence of ferrous iron. The reduction of selenite and formation of Se (0) was found to be a surface-mediated reaction by iron oxides. Without the presence of the reactive surface of freshly precipitated iron oxides, the reduction reaction could not be detected, even under a well controlled low oxygen environment (30 ppmv). Our results clearly illustrate the crucial role of iron oxide in this redox process. In lake sediments, the complex sediment matrix seems to strongly adsorb SeO(2-) and make it less available for reduction into Se(0). When lake sediments were submitted to UV irradiation to eliminate bacteria, the percentage of iron oxides increased and it was found that higher levels of iron oxides, generated by the UV treatment, correlated with the higher formation of Se(0). Moreover, the results of our field studies on two distinctively different lake sediments also showed a strong influence of iron oxides on the formation of elemental Se, which agrees well with our laboratory simulations.
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Affiliation(s)
- Yu-Wei Chen
- Department of Chemistry and Biochemistry, Laurentian University, 935 Ramsey Lake Road, Sudbury, Ontario P3E2C6, Canada
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35
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Afton SE, Catron B, Caruso JA. Elucidating the selenium and arsenic metabolic pathways following exposure to the non-hyperaccumulating Chlorophytum comosum, spider plant. JOURNAL OF EXPERIMENTAL BOTANY 2009; 60:1289-97. [PMID: 19273464 PMCID: PMC2657536 DOI: 10.1093/jxb/erp003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Although many studies have investigated the metabolism of selenium and arsenic in hyperaccumulating plants for phytoremediation purposes, few have explored non-hyperaccumulating plants as a model for general contaminant exposure to plants. In addition, the result of simultaneous supplementation with selenium and arsenic has not been investigated in plants. In this study, Chlorophytum comosum, commonly known as the spider plant, was used to investigate the metabolism of selenium and arsenic after single and simultaneous supplementation. Size exclusion and ion-pairing reversed phase liquid chromatography were coupled to an inductively coupled plasma mass spectrometer to obtain putative metabolic information of the selenium and arsenic species in C. comosum after a mild aqueous extraction. The chromatographic results depict that selenium and arsenic species were sequestered in the roots and generally conserved upon translocation to the leaves. The data suggest that selenium was directly absorbed by C. comosum roots when supplemented with Se(VI), but a combination of passive and direct absorption occurred when supplemented with Se(IV) due to the partial oxidation of Se(IV) to Se(VI) in the rhizosphere. Higher molecular weight selenium species were more prevalent in the roots of plants supplemented with Se(IV), but in the leaves of plants supplemented with Se(VI) due to an increased translocation rate. When supplemented as As(III), arsenic is proposed to be passively absorbed as As(III) and partially oxidized to As(V) in the plant root. Although total elemental analysis demonstrates a selenium and arsenic antagonism, a compound containing selenium and arsenic was not present in the general aqueous extract of the plant.
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36
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Takada T, Hirata M, Kokubu S, Toorisaka E, Ozaki M, Hano T. Kinetic study on biological reduction of selenium compounds. Process Biochem 2008. [DOI: 10.1016/j.procbio.2008.06.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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37
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Lenz M, van Hullebusch ED, Farges F, Nikitenko S, Borca CN, Grolimund D, Lens PNL. Selenium speciation assessed by X-ray absorption spectroscopy of sequentially extracted anaerobic biofilms. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2008; 42:7587-7593. [PMID: 18983079 DOI: 10.1021/es800811q] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Wet chemical methods such as sequential extraction procedures are commonly used to assess selenium fractionation in anoxic environments, allowing an estimation of the mobility and bioavailability of selenium. However, the interpretation can be biased by unselective extraction of targeted species and artifacts introduced during the extraction. Here, the selectivity of the single extraction steps to gain reliable selenium speciation information are scrutinized for the first time by direct, nondestructive X-ray absorption near edge structure (XANES) spectroscopy at the selenium K-edge. The sequential extraction procedures seriously overestimated the elemental selenium fraction, as major parts (58%) of the total selenium were present as metal selenides and organic selenium compounds, although extracted in the elemental fraction. Spectral fitting of the XANES spectra by the least-squares linear combinations utilizing a large set of model compounds, including previously neglected Se(-I) selenides, showed a novel degree of complexity in the speciation of selenium treating anaerobic biofilms, with up to 4 modeled selenium species contributing to the speciation, i.e., different elemental, organic, and metal-bound selenium species. Furthermore, a short exposure (10 min) to ambient air during the sequential extraction procedure induced the oxidation of organic selenium compounds, revealing the fragility of selenium speciation in anaerobic biofilms.
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Affiliation(s)
- Markus Lenz
- Sub-Department of Environmental Technology, Wageningen University, Wageningen, The Netherlands
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38
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Lenz M, Janzen N, Lens PNL. Selenium oxyanion inhibition of hydrogenotrophic and acetoclastic methanogenesis. CHEMOSPHERE 2008; 73:383-388. [PMID: 18653211 DOI: 10.1016/j.chemosphere.2008.05.059] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2008] [Revised: 05/08/2008] [Accepted: 05/18/2008] [Indexed: 05/26/2023]
Abstract
Inhibitory effects of selenite and selenate towards hydrogenotrophic and acetoclastic methanogenesis were evaluated in anaerobic toxicity assays. The 50% inhibitory concentration (IC50) of both selenium oxyanions was below 6.1x10(-5)M in hydrogenotrophic assays, whereas acetoclastic methanogens were less inhibited: IC50=8.3x10(-5)M and 5.5x10(-4)M for selenite and selenate, respectively. Selenite completely inhibits methanogenesis from both substrates tested at concentrations > or =10(-3)M selenite, while only marginal methanogenic activities occur at equimolar concentrations of selenate. Selenite becomes irreversibly inhibitory upon a single exposure, whereas selenate inhibits methanogens upon repeated exposure. Consequently, methane recovery can be seriously hampered or even impossible during anaerobic treatment of highly selenium contaminated waste streams.
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Affiliation(s)
- Markus Lenz
- Sub-Department of Environmental Technology, Wageningen University, 6700 EV Wageningen, The Netherlands
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39
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Pearce CI, Coker VS, Charnock JM, Pattrick RAD, Mosselmans JFW, Law N, Beveridge TJ, Lloyd JR. Microbial manufacture of chalcogenide-based nanoparticles via the reduction of selenite using Veillonella atypica: an in situ EXAFS study. NANOTECHNOLOGY 2008; 19:155603. [PMID: 21825617 DOI: 10.1088/0957-4484/19/15/155603] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The ability of metal-reducing bacteria to produce nanoparticles, and their precursors, can be harnessed for the biological manufacture of fluorescent, semiconducting nanomaterials. The anaerobic bacterium Veillonella atypica can reduce selenium oxyanions to form nanospheres of elemental selenium. These selenium nanospheres are then further reduced by the bacterium to form reactive selenide which could be precipitated with a suitable metal cation to produce nanoscale chalcogenide precipitates, such as zinc selenide, with optical and semiconducting properties. The whole cells used hydrogen as the electron donor for selenite reduction and an enhancement of the reduction rate was observed with the addition of a redox mediator (anthraquinone disulfonic acid). A novel synchrotron-based in situ time-resolved x-ray absorption spectroscopy technique was used, in conjunction with ion chromatography and inductively coupled plasma-atomic emission spectroscopy, to study the mechanisms and kinetics of the microbial reduction of selenite to selenide. The products of this biotransformation were also assessed using electron microscopy, energy-dispersive spectroscopy, x-ray diffraction and fluorescence spectroscopy. This process offers the potential to prepare chalcogenide-based nanocrystals, for application in optoelectronic devices and biological labelling, from more environmentally benign precursors than those used in conventional organometallic synthesis.
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Affiliation(s)
- Carolyn I Pearce
- School of Earth, Atmospheric and Environmental Sciences and Williamson Research Centre for Molecular Environmental Science, University of Manchester, Manchester M13 9PL, UK
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40
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Lenz M, Hullebusch EDV, Hommes G, Corvini PFX, Lens PNL. Selenate removal in methanogenic and sulfate-reducing upflow anaerobic sludge bed reactors. WATER RESEARCH 2008; 42:2184-2194. [PMID: 18177686 DOI: 10.1016/j.watres.2007.11.031] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Revised: 11/16/2007] [Accepted: 11/24/2007] [Indexed: 05/25/2023]
Abstract
This paper evaluates the use of upflow anaerobic sludge bed (UASB) bioreactors (30 degrees C, pH=7.0) to remove selenium oxyanions from contaminated waters (790 microg Se L(-1)) under methanogenic and sulfate-reducing conditions using lactate as electron donor. One UASB reactor received sulfate at different sulfate to selenate ratios, while another UASB was operated under methanogenic conditions for 132 days without sulfate in the influent. The selenate effluent concentrations in the sulfate-reducing and methanogenic reactor were 24 and 8 microg Se L(-1), corresponding to removal efficiencies of 97% and 99%, respectively. X-ray diffraction (XRD) analysis and sequential extractions showed that selenium was mainly retained as elemental selenium in the biomass. However, the total dissolved selenium effluent concentrations amounted to 73 and 80 microg Se L(-1), respectively, suggesting that selenate was partly converted to another selenium compound, most likely colloidally dispersed Se(0) nanoparticles. Possible intermediates of selenium reduction (selenite, dimethylselenide, dimethyldiselenide, H(2)Se) could not be detected. Sulfate reducers removed selenate at molar excess of sulfate to selenate (up to a factor of 2600) and elevated dissolved sulfide concentrations (up to 168 mg L(-1)), but selenium removal efficiencies were limited by the applied sulfate-loading rate. In the methanogenic bioreactor, selenate and dissolved selenium removal were independent of the sulfate load, but inhibited by sulfide (101 mg L(-1)). The selenium removal efficiency of the methanogenic UASB abruptly improved after 58 days of operation, suggesting that a specialized selenium-converting population developed in the reactor. This paper demonstrates that both sulfate-reducing and methanogenic UASB reactors can be applied to remove selenate from contaminated natural waters and anthropogenic waste streams, e.g. agricultural drainage waters, acid mine drainage and flue gas desulfurization bleeds.
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Affiliation(s)
- Markus Lenz
- Sub-Department of Environmental Technology, Wageningen University, Wageningen, The Netherlands.
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41
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Wen H, Carignan J, Hu R, Fan H, Chang B, Yang G. Large selenium isotopic variations and its implication in the Yutangba Se deposit, Hubei Province, China. ACTA ACUST UNITED AC 2007. [DOI: 10.1007/s11434-007-0320-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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42
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Knotek-Smith HM, Crawford DL, Möller G, Henson RA. Microbial studies of a selenium-contaminated mine site and potential for on-site remediation. J Ind Microbiol Biotechnol 2006; 33:897-913. [PMID: 16804682 DOI: 10.1007/s10295-006-0149-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2004] [Accepted: 05/17/2006] [Indexed: 10/24/2022]
Abstract
Surface water Selenium (Se) concentrations are above regulatory standards at several active and inactive phosphate mine sites in the US Western Phosphate Resource Area. The focus of the present study was to examine the impacts of the microbial communities on the oxidation state of Se in overburden waste from the Smoky Canyon phosphate mine in Idaho, USA. Microbial populations were found that reduce soluble selenate (SeO (4) (2-) ) to insoluble elemental Se. Microcosm experiments were conducted for molecular genetic analysis of this microbial community by rRNA gene profiling. An acetone pretreatment step was developed to remove interfering pre-petroleum hydrocarbons from the samples prior to extraction. PCR was used to amplify 16S and 18S rRNA genes present in the microbial community DNA. The amplified products were subjected to denaturing gradient gel electrophoresis (DGGE). Isolates and excised DGGE bands were amplified and sequenced for identification to determine the relative importance of culturable isolates to the total microbial population. Analysis of samples from different sites at the mine showed how Se contamination and previous remediation treatments changed the microbial populations across the site. Members of the family Enterobacteriaceae were dominant among the selenate reducing isolates from the site containing high Se levels. In particular, Serratia fonticola was isolated repeatedly from contaminated Smoky Canyon Mine site samples. Packed column studies were performed with seleniferous waste rock fractions from Smoky Canyon Mine. Column amendments consisted of combinations of iron, compost, and whey. Eh, pH, and extractable Se measurements were taken. Tests with infiltrated water showed columns containing an organic amendment combined with iron metal were the most resistant to Se leaching. Iron-based compounds from the corroding metal are thought to strongly bind the Se reduced by microbial activity, thereby stabilizing the Se in an insoluble form. We conclude that long-term stabilization of selenium at contaminated mine sites may require reductive microbial processes combined with abiotic immobilization by iron, either natural or engineered, to stabilize the Se and retard re-oxidation and release. Iron-selenide or iron-selenite compounds are more stable and resistant to leaching, especially when removed from active weathering.
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Affiliation(s)
- Heather M Knotek-Smith
- Department of Agricultural and Biological Systems Engineering, University of Idaho, Moscow, ID, 83844-2060, USA
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43
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Hockin S, Gadd GM. Removal of selenate from sulfate-containing media by sulfate-reducing bacterial biofilms. Environ Microbiol 2006; 8:816-26. [PMID: 16623739 DOI: 10.1111/j.1462-2920.2005.00967.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A biofilm-selected strain of a Desulfomicrobium sp. removed selenate from solution to sub-micromolar concentrations during growth on lactate (or hydrogen) and sulfate. Under sulfate-limited growth conditions, selenium was enzymatically reduced to selenide. Under excess sulfate conditions, selenate removal was primarily by enzymatic reduction to elemental selenium. Sequestration by biofilms was greater under the latter condition. Experiments with washed cell suspensions showed that high sulfate concentrations inhibited cell-specific selenate reduction, but when growing cells were exposed to selenate, the biomass increase achieved during incubations with abundant sulfate resulted in more rapid selenate removal. The addition of small amounts of sulfite, or thiosulfate, ameliorated this inhibition. Nitrate also inhibited selenate reduction in washed cell suspensions, apparently due to a general oxidizing effect. These results suggest that where biofilm-based sulfate-reducing bacteria (SRB) bioreactors are considered for the treatment of mixed metalliferous wastes that contain selenium oxyanions, adequate selenate removal should be achievable under a range of environmental conditions. The form and fate of the precipitated product will, however, be influenced by the dominant reduction pathway, which is controlled by environmental variables.
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Affiliation(s)
- Simon Hockin
- Division of Environmental and Applied Biology, Biological Sciences Institute, School of Life Sciences, University of Dundee, Dundee, DD1 4HN, UK
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44
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Ansede JH, Yoch DC. Comparison of selenium and sulfur volatilization by dimethylsulfoniopropionate lyase (DMSP) in two marine bacteria and estuarine sediments. FEMS Microbiol Ecol 2006. [DOI: 10.1111/j.1574-6941.1997.tb00412.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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45
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Hockin SL, Gadd GM. Linked redox precipitation of sulfur and selenium under anaerobic conditions by sulfate-reducing bacterial biofilms. Appl Environ Microbiol 2003; 69:7063-72. [PMID: 14660350 PMCID: PMC309891 DOI: 10.1128/aem.69.12.7063-7072.2003] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2003] [Accepted: 08/27/2003] [Indexed: 11/20/2022] Open
Abstract
A biofilm-forming strain of sulfate-reducing bacteria (SRB), isolated from a naturally occurring mixed biofilm and identified by 16S rDNA analysis as a strain of Desulfomicrobium norvegicum, rapidly removed 200 micro M selenite from solution during growth on lactate and sulfate. Elemental selenium and elemental sulfur were precipitated outside SRB cells. Precipitation occurred by an abiotic reaction with bacterially generated sulfide. This appears to be a generalized ability among SRB, arising from dissimilatory sulfide biogenesis, and can take place under low redox conditions and in the dark. The reaction represents a new means for the deposition of elemental sulfur by SRB under such conditions. A combination of transmission electron microscopy, environmental scanning electron microscopy, and cryostage field emission scanning electron microscopy were used to reveal the hydrated nature of SRB biofilms and to investigate the location of deposited sulfur-selenium in relation to biofilm elements. When pregrown SRB biofilms were exposed to a selenite-containing medium, nanometer-sized selenium-sulfur granules were precipitated within the biofilm matrix. Selenite was therefore shown to pass through the biofilm matrix before reacting with bacterially generated sulfide. This constitutes an efficient method for the removal of toxic concentrations of selenite from solution. Implications for environmental cycling and the fate of sulfur and selenium are discussed, and a general model for the potential action of SRB in selenium transformations is presented.
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Affiliation(s)
- Simon L Hockin
- Division of Environmental and Applied Biology, Biological Sciences Institute, School of Life Sciences, University of Dundee, Dundee DD1 4HN, Scotland, United Kingdom
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46
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Oremland RS, Blum JS, Bindi AB, Dowdle PR, Herbel M, Stolz JF. Simultaneous reduction of nitrate and selenate by cell suspensions of selenium-respiring bacteria. Appl Environ Microbiol 1999; 65:4385-92. [PMID: 10508064 PMCID: PMC91582 DOI: 10.1128/aem.65.10.4385-4392.1999] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Washed-cell suspensions of Sulfurospirillum barnesii reduced selenate [Se(VI)] when cells were cultured with nitrate, thiosulfate, arsenate, or fumarate as the electron acceptor. When the concentration of the electron donor was limiting, Se(VI) reduction in whole cells was approximately fourfold greater in Se(VI)-grown cells than was observed in nitrate-grown cells; correspondingly, nitrate reduction was approximately 11-fold higher in nitrate-grown cells than in Se(VI)-grown cells. However, a simultaneous reduction of nitrate and Se(VI) was observed in both cases. At nonlimiting electron donor concentrations, nitrate-grown cells suspended with equimolar nitrate and selenate achieved a complete reductive removal of nitrogen and selenium oxyanions, with the bulk of nitrate reduction preceding that of selenate reduction. Chloramphenicol did not inhibit these reductions. The Se(VI)-respiring haloalkaliphile Bacillus arsenicoselenatis gave similar results, but its Se(VI) reductase was not constitutive in nitrate-grown cells. No reduction of Se(VI) was noted for Bacillus selenitireducens, which respires selenite. The results of kinetic experiments with cell membrane preparations of S. barnesii suggest the presence of constitutive selenate and nitrate reduction, as well as an inducible, high-affinity nitrate reductase in nitrate-grown cells which also has a low affinity for selenate. The simultaneous reduction of micromolar Se(VI) in the presence of millimolar nitrate indicates that these organisms may have a functional use in bioremediating nitrate-rich, seleniferous agricultural wastewaters. Results with (75)Se-selenate tracer show that these organisms can lower ambient Se(VI) concentrations to levels in compliance with new regulations proposed for release of selenium oxyanions into the environment.
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Affiliation(s)
- R S Oremland
- U.S. Geological Survey, Menlo Park, California 94025, USA.
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47
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Avazéri C, Turner RJ, Pommier J, Weiner JH, Giordano G, Verméglio A. Tellurite reductase activity of nitrate reductase is responsible for the basal resistance of Escherichia coli to tellurite. MICROBIOLOGY (READING, ENGLAND) 1997; 143 ( Pt 4):1181-1189. [PMID: 9141681 DOI: 10.1099/00221287-143-4-1181] [Citation(s) in RCA: 124] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Tellurite and selenate reductase activities were identified in extracts of Escherichia coli. These activities were detected on non-denaturing polyacrylamide gels using an in situ methyl viologen activity-staining technique. The activity bands produced from membrane-protein extracts had the same RF values as those of nitrate reductases (NRs) A and Z. Tellurite and selenate reductase activities were absent from membranes obtained from mutants deleted in NRs A and Z. Further evidence of the tellurite and selenate reductase activities of NR was demonstrated using rocket immunoelectrophoresis analysis, where the tellurite and selenate reductase activities corresponded to the precipitation arc of NR. Additionally, hypersensitivity to potassium tellurite was observed under aerobic growth conditions in nar mutants. The tac promoter expression of NR A resulted in elevated tellurite resistance. The data obtained also imply that a minimal threshold level of NR A is required to increase resistance. Under anaerobic growth conditions additional tellurite reductase activity was identified in the soluble fraction on non-denaturing gels. Nitrate reductase mutants were not hypersensitive under anaerobic conditions, possibly due to the presence of this additional reductase activity.
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Affiliation(s)
- Cécile Avazéri
- Laboratoire de Bioénergétique Cellulaire, Département d'Ecophysiologie Végétale et Microbiologie, CEA Cadarache, 13108 Saint Paul lez Durance, France
| | - Raymond J Turner
- MRC Group in the Molecular Biology of Membranes, Department of Biochemistry, University of Alberta, Edmonton, Alberta, T6G 2H7Canada
| | - Jeanine Pommier
- Laboratoire de Chimie Bactérienne, CNRS, 31 Chemin Joseph Augier, 13402 Marseille Cedex 20, France
| | - Joël H Weiner
- MRC Group in the Molecular Biology of Membranes, Department of Biochemistry, University of Alberta, Edmonton, Alberta, T6G 2H7Canada
| | - Gérard Giordano
- Laboratoire de Chimie Bactérienne, CNRS, 31 Chemin Joseph Augier, 13402 Marseille Cedex 20, France
| | - André Verméglio
- Laboratoire de Bioénergétique Cellulaire, Département d'Ecophysiologie Végétale et Microbiologie, CEA Cadarache, 13108 Saint Paul lez Durance, France
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48
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Transformation of selenate and selenite to elemental selenium byDesulfovibrio desulfuricans. ACTA ACUST UNITED AC 1995. [DOI: 10.1007/bf01569947] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Oremland RS, Blum JS, Culbertson CW, Visscher PT, Miller LG, Dowdle P, Strohmaier FE. Isolation, Growth, and Metabolism of an Obligately Anaerobic, Selenate-Respiring Bacterium, Strain SES-3. Appl Environ Microbiol 1994; 60:3011-9. [PMID: 16349362 PMCID: PMC201757 DOI: 10.1128/aem.60.8.3011-3019.1994] [Citation(s) in RCA: 108] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A gram-negative, strictly anaerobic, motile vibrio was isolated from a selenate-respiring enrichment culture. The isolate, designated strain SES-3, grew by coupling the oxidation of lactate to acetate plus CO
2
with the concomitant reduction of selenate to selenite or of nitrate to ammonium. No growth was observed on sulfate or selenite, but cell suspensions readily reduced selenite to elemental selenium (Se
0
). Hence, SES-3 can carry out a complete reduction of selenate to Se
0
. Washed cell suspensions of selenate-grown cells did not reduce nitrate, and nitrate-grown cells did not reduce selenate, indicating that these reductions are achieved by separate inducible enzyme systems. However, both nitrate-grown and selenate-grown cells have a constitutive ability to reduce selenite or nitrite. The oxidation of [
14
C]lactate to
14
CO
2
coupled to the reduction of selenate or nitrate by cell suspensions was inhibited by CCCP (carbonyl cyanide
m
-chlorophenylhydrazone), cyanide, and azide. High concentrations of selenite (5 mM) were readily reduced to Se
0
by selenate-grown cells, but selenite appeared to block the synthesis of pyruvate dehydrogenase. Tracer experiments with [
75
Se]selenite indicated that cell suspensions could achieve a rapid and quantitative reduction of selenite to Se
0
. This reduction was totally inhibited by sulfite, partially inhibited by selenate or nitrite, but unaffected by sulfate or nitrate. Cell suspensions could reduce thiosulfate, but not sulfite, to sulfide. These results suggest that reduction of selenite to Se
0
may proceed, in part, by some of the components of a dissimilatory system for sulfur oxyanions.
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Affiliation(s)
- R S Oremland
- U.S. Geological Survey, Menlo Park, California 94025
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Affiliation(s)
- J Heider
- Lehrstuhl für Mikrobiologie, Universität München, Germany
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