Methylation of inorganic lead by Tamar Estuary (UK) sediments

Walton, Andrew P.; Ebdon, Les; Millward, G.E.

doi:10.1002/aoc.590020113

Cited by 17 publications

(9 citation statements)

References 11 publications

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“…The biomethylation of Pb(II) has been reported to be catalysed by Pseudomonas sp. (Walton et al , 1988; Wong et al , 1975), Alcaligenes sp. (Wong et al , 1975), Acinetobacter sp.…”

Section: Introductionmentioning

confidence: 99%

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Lead resistance in micro-organisms

2014

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Lead (Pb) is an element present in the environment that negatively affects all living organisms. To diminish its high toxicity, micro-organisms have developed several mechanisms that allow them to survive exposure to Pb(II). The main mechanisms of lead resistance involve adsorption by extracellular polysaccharides, cell exclusion, sequestration as insoluble phosphates, and ion efflux to the cell exterior. This review describes the various lead resistance mechanisms, and the regulation of their expression by lead binding regulatory proteins. Special attention is given to the Pbr system from Cupriavidus metallidurans CH34, which involves a unique mechanism combining efflux and lead precipitation.

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“…The biomethylation of Pb(II) has been reported to be catalysed by Pseudomonas sp. (Walton et al , 1988; Wong et al , 1975), Alcaligenes sp. (Wong et al , 1975), Acinetobacter sp.…”

Section: Introductionmentioning

confidence: 99%

“…(Wong et al , 1975) and Bacillus sp. (Walton et al , 1988). In general, two forms of volatile methylated lead have been identified as products of microbial activity: tetramethyl (Me 4 Pb) and trimethyl (Me 3 Pb) lead.…”

Section: Introductionmentioning

confidence: 99%

Lead resistance in micro-organisms

2014

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“…In concentrated solutions, 1 decomposed rapidly to a black insoluble material. Deprotection of 1 with sodium tetraborate (borax) in MeOH/THF, which is the mildest method for the deprotection of Me,Si-substituted alkynes [25], was rapid and quantitative, but decomposition of the formed parent C,,H4 chromophore 3 occurred immediately upon evaporation of solvent. Even in dilute solution, 3 decomposed rapidly and could, therefore, not be characterized.…”

mentioning

confidence: 99%

Macrocyclic Tetraethynylethene Molecular Scaffolding: Perethynylated aromatic dodecadehydro[18]annulenes, antiaromatic octadehydro[12]annulenes, and expanded radialenes

Anthony¹,

Boldi²,

Boudon³

et al. 1995

Helvetica Chimica Acta

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Tetraethynylethene (3,4-diethynylhex-3-ene-1,5-diyne) molecular scaffolding provided access to novel macrocyclic nanometer-sized C-rich molecules with unusual structural and electronic properties. Starting from cis-bisdeprotected cis -bis(trialkylsilyl)-protected tetraethynylethenes, the per(silylethyny1)ated octadehydro[ 12lannul-enes 1 and 2 and the corresponding dodecadehydro[l8]annulenes 4 and 5 were prepared by oxidative Huy coupling.X-Ray crystal-structure analyses of (i-Pr)$i-protected 2 and Me,Si-protected 4 showed that both annulene perimeters are perfectly planar. Electronic absorption spectral comparisons provided strong evidence that the macro rings in the deep-purple-colored 1 and 2 are antiaromatic (4n n-electrons), whereas those in yellow 4 and 5 are aromatic ((4n + 2) n-electrons). Although unstable in solution, the antiaromatic compound 2 gave high-melting crystals in which the individual octadehydro[l2]annulene chromophores are isolated and stabilized in a matrix-type environment formed by the bulky (i-Pr)$i groups. Electrochemical studies demonstrated that the antiaromatic octadehydro[ 12lannulene 2 undergoes two stepwise one-electron reductions more readily than the aromatic chromophore 5. This redox behavior is best explained by the formation of an aromatic (4n + 2) n-electron dianion from 2, whereas 5 loses its aromaticity upon reduction. The Me$i derivative 4 was deprotected with borax in MeOH/THF to give the highly unstable hexaethynyl-dodecadehydro[ 1 Blannulene 6, a C,oH6 isomer and macrocyclic precursor to a two-dimensional all-C-network. Deprotection of 2 did not give isolable amounts of tetraethynyl-octadehydro[l2]annulene 3 due to the extreme instability of the latter. Starting from dirneric and trimeric acyclic tetraethynylethene oligomers, a series of expanded radialenes were obtained. They possess large C-cores with silylethynyl-protected peripheral valences and can be viewed as persilylated C,, (7), C,, (S), and C60 (9) isomers. These expanded C-sheets are high-melting, highly stable, soluble materials which were readily characterized by laser-desorption time-of-flight (LD-TOF) mass spectrometry. Due to inefficient macrocyclic cross-conjugation and/or non-planarity, the extent of rr-electron delocalization in 7-9 is limited to the longest linearly conjugated n-electron fragment. In agreement with these properties, all three expanded radialenes exhibited similar redox behavior; they are difficult to oxidize but undergo several reversible one-electron reductions in similar potential ranges. Presumably, the reduced n-electron delocalization is also at the origin of the particularly high stability of 7-9.

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“…Moreover, Pb is not an essential nutrient in the metabolic processes of plants and/or animals, and it can accumulate to high levels and become toxic to organisms. [8][9][10] were capable of converting organic/ inorganic forms of Pb into less toxic derivatives. Several chemical methods have been developed to control the dispersion and biomagnication of metals from contaminated soil.…”

Section: Introductionmentioning

confidence: 99%

“…7 Several studies reported that the bacterial strains such as Pseudomonas sp., Bacillus sp., Acinetobacter sp., Flavobacterium sp., Aeromonas sp. [8][9][10] were capable of converting organic/ inorganic forms of Pb into less toxic derivatives. However, survival of the bacteria in the contaminated soil is essential for biotransformation of Pb since these reactions are enzyme mediated.…”

Section: Introductionmentioning

confidence: 99%

Lead biotransformation potential of allochthonous Bacillus sp. SKK11 with sesame oil cake extract in mine soil

Govarthanan

Park

et al. 2015

RSC Adv.

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The potential of allochthonous Bacillus sp. SKK11 and sesame oil cake extract for the immobilization of Pb in mine soil was investigated in this study. The isolate SKK11, isolated from a brackish environment and identified as Bacillus sp. based on partial 16S rDNA sequencing, exhibited maximum resistance to Pb (750 mg L À1 ). Growth kinetic studies revealed that the presence of oil cake extract (2%) increased the biomass of the isolate SKK11. Transmission electron microscopy and X-ray diffraction studies showed that isolate SKK11 transformed Pb either intracellularly or extracellularly. Selective sequential extraction studies showed that the bioremediation decreased 24.9% of the exchangeable fraction in the mine soil in 3 days. However, 75.1% of the exchangeable fraction was not immobilized in the soil. An X-ray diffractogram of the bioremediated soil showed a major decrease (79.0%) in the intensity of the plagioclase mineral peak. Urease, dehydrogenase, amylase, invertase, cellulase, and alkaline phosphatase enzyme activities were increased in the bioremediated mine soil. These results suggest that the isolate Bacillus sp. SKK11 in combination with sesame oil cake extract could be employed for the immobilization of bioavailable Pb in contaminated soil.

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Methylation of inorganic lead by Tamar Estuary (UK) sediments

Cited by 17 publications

References 11 publications

Lead resistance in micro-organisms

Lead resistance in micro-organisms

Macrocyclic Tetraethynylethene Molecular Scaffolding: Perethynylated aromatic dodecadehydro[18]annulenes, antiaromatic octadehydro[12]annulenes, and expanded radialenes

Lead biotransformation potential of allochthonous Bacillus sp. SKK11 with sesame oil cake extract in mine soil

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