Selenium, Tellurium and Polonium

Bagnall, Kenneth W.

doi:10.1016/b978-0-08-018856-0.50008-0

Cited by 25 publications

(33 citation statements)

References 2 publications

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“…The presence of Te-containing compounds with different pdtc-to-Te ratios depended on the molar ratios of pdtc to tellurite used for the reactions. When equimolar concentrations were used, (pdtc)Te was detected mainly with some (pdtc) 2 Te. When a twofold-higher pdtc concentration was used for the reaction, (pdtc) 2 Te was predominant, with some (pdtc) 3 , m/z 138.0) were found (spectra not shown).…”

Section: Resultsmentioning

confidence: 99%

“…When equimolar concentrations were used, (pdtc)Te was detected mainly with some (pdtc) 2 Te. When a twofold-higher pdtc concentration was used for the reaction, (pdtc) 2 Te was predominant, with some (pdtc) 3 , m/z 138.0) were found (spectra not shown). Structures of the pdtc tellurides were proposed based on the fragmentation patterns of the parent molecules seen during ESI-MS/MS daughter analysis (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Tellurium is a relatively rare element found in nature in the form of metal tellurides (e.g., Pb, Cu, Ag, Au, and Sb). Industrial waste discharge sites can contain elevated concentrations of Te (2). Te(IV) as tellurite (TeO 3 2Ϫ ) is more toxic to most gram-negative bacteria than Se(IV) in the form of selenite.…”

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confidence: 99%

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Pyridine-2,6-Bis(Thiocarboxylic Acid) Produced by Pseudomonas stutzeri KC Reduces and Precipitates Selenium and Tellurium Oxyanions

Zawadzka

Crawford

Paszczyński

2006

Appl Environ Microbiol

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The siderophore of Pseudomonas stutzeri KC, pyridine-2,6-bis(thiocarboxylic acid) (pdtc), is shown to detoxify selenium and tellurium oxyanions in bacterial cultures. A mechanism for pdtc's detoxification of tellurite and selenite is proposed. The mechanism is based upon determination using mass spectrometry and energydispersive X-ray spectrometry of the chemical structures of compounds formed during initial reactions of tellurite and selenite with pdtc. Selenite and tellurite are reduced by pdtc or its hydrolysis product H 2 S, forming zero-valent pdtc selenides and pdtc tellurides that precipitate from solution. These insoluble compounds then hydrolyze, releasing nanometer-sized particles of elemental selenium or tellurium. Electron microscopy studies showed both extracellular precipitation and internal deposition of these metalloids by bacterial cells. The precipitates formed with synthetic pdtc were similar to those formed in pdtc-producing cultures of P. stutzeri KC. Culture filtrates of P. stutzeri KC containing pdtc were also active in removing selenite and precipitating elemental selenium and tellurium. The pdtc-producing wild-type strain KC conferred higher tolerance against selenite and tellurite toxicity than a pdtc-negative mutant strain, CTN1. These observations support the hypothesis that pdtc not only functions as a siderophore but also is involved in an initial line of defense against toxicity from various metals and metalloids.Siderophores are iron-specific chelators that are produced and excreted by microorganisms under iron-limiting conditions as a part of an iron acquisition system. Some siderophores chelate metals other than iron, forming soluble or insoluble metal compounds and affecting the mobility and toxicity of those metals (8,17,47). Pyridine-2,6-bis(thiocarboxylic acid) (pdtc) is a siderophore produced by Pseudomonas stutzeri KC and P. putida DSM 3601 and DSM 3602 that has fortuitous carbon tetrachloride degradation activity (21, 30). Recent research has shown that pdtc promotes iron transport into the cell (25). P. stutzeri KC, its spontaneous pdtc-negative mutant CTN1, and other P. stutzeri strains also produce proferrioxamines (pFOs), which are probably their primary siderophores (A. Zawadzka et al., unpublished data). pdtc is a broad-range metal chelator; it chelates many transition metals, some heavy metals, lanthanides, and actinides. In general, micronutrient metals chelated by pdtc are soluble, while toxic metals form insoluble precipitates with pdtc (8, 39). Selenium and tellurium oxyanions are among the toxic metalloids precipitated by pdtc and pdtc-producing Pseudomonas stutzeri KC cultures.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Pyridine-2,6-Bis(Thiocarboxylic Acid) Produced by Pseudomonas stutzeri KC Reduces and Precipitates Selenium and Tellurium Oxyanions

Zawadzka

Crawford

Paszczyński

2006

Appl Environ Microbiol

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“…Te is relatively rare in the environment, but it can be found at high concentrations near waste discharge sites. Native elemental Te is uncommon (an abundance in the lithosphere of 2 ϫ 10 Ϫ7 %), usually occurring in conjunction with elemental sulfur or as tellurides of lead, copper, silver, gold, and antimony (2). The extraction of Te is difficult because of its low content in natural ores, and Te compounds are usually obtained as by-products of metal-refining processes (20).…”

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confidence: 99%

Isolation of Tellurite- and Selenite-Resistant Bacteria from Hydrothermal Vents of the Juan de Fuca Ridge in the Pacific Ocean

Rathgeber

Yurkova

Stackebrandt

et al. 2002

Appl Environ Microbiol

101

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Deep-ocean hydrothermal-vent environments are rich in heavy metals and metalloids and present excellent sites for the isolation of metal-resistant microorganisms. Both metalloid-oxide-resistant and metalloid-oxidereducing bacteria were found. Tellurite-and selenite-reducing strains were isolated in high numbers from ocean water near hydrothermal vents, bacterial films, and sulfide-rich rocks. Growth of these isolates in media containing K 2 TeO 3 or Na 2 SeO 3 resulted in the accumulation of metallic tellurium or selenium. The MIC of K 2 TeO 3 ranged from 1,500 to greater than 2,500 g/ml, and the MIC of Na 2 SeO 3 ranged from 6,000 to greater than 7,000 g/ml for 10 strains. Phylogenetic analysis of 4 of these 10 strains revealed that they form a branch closely related to members of the genus Pseudoalteromonas, within the ␥-3 subclass of the Proteobacteria. All 10 strains were found to be salt tolerant, pH tolerant, and thermotolerant. The metalloid resistance and morphological, physiological, and phylogenetic characteristics of newly isolated strains are described.

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“…Also, in the manner of TeCl 4 , it forms bright yellow solutions in aqueous HCl, which suggests the formation of the hexachloropolonates. The formation of PoCl 6 2− in 12.2 M HCl is highly probable, but not definitive.…”

Section: Chlorine Compounds Of Poloniummentioning

confidence: 99%

Polonium: Inorganic Chemistry

Zingaro¹

2005

Encyclopedia of Inorganic and Bioinorganic Chemistry

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The chemistry of polonium is quite limited. Because all of the isotopes of this element are radioactive, and because it is available in such limited quantities, research with polonium is difficult. The metal has been isolated and characterized. Although a number of polonium compounds, such as PoO2 have been well characterized, the evidence for many is insubstantial. Among the halide derivatives, PoCl4 has been studied in greatest detail. A number of other halides, and their complex ions such as PoBr6‐2, have been studied with considerable success. A simple binary nitride has never been prepared, and only indirect evidence for the existence of H2Po has been reported.

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Selenium, Tellurium and Polonium

Cited by 25 publications

References 2 publications

Pyridine-2,6-Bis(Thiocarboxylic Acid) Produced by Pseudomonas stutzeri KC Reduces and Precipitates Selenium and Tellurium Oxyanions

Pyridine-2,6-Bis(Thiocarboxylic Acid) Produced by Pseudomonas stutzeri KC Reduces and Precipitates Selenium and Tellurium Oxyanions

Isolation of Tellurite- and Selenite-Resistant Bacteria from Hydrothermal Vents of the Juan de Fuca Ridge in the Pacific Ocean

Polonium: Inorganic Chemistry

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