Studies on biological methylation. Part XIV. The formation of trimethylarsine and dimethyl selenide in mould cultures from methyl sources containing 14C

Challenger, Frederick; Lisle, D. B.; Dransfield, Philip B.

doi:10.1039/jr9540001760

Cited by 46 publications

(8 citation statements)

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“…The methylation of Se has been shown to be mainly a biotic process [1,23,27,44,49] and is primarily thought to be a protective mechanism to detoxify the microorganisms surrounding environment. The predominant groups of Se-methylating organisms isolated from soils and sediments are bacteria and fungi [1,2,4,8,26], while bacteria are thought to be the active Se methylating organisms in water [5,6,9,37,43,49]. The volatile Se compound produced by most organisms is DMSe [8,9,16,[25][26][27]46] which, being a gas, escapes to the environment.…”

Section: Methylation Of Se In Soil and Watermentioning

confidence: 99%

Bioremediation of selenium‐contaminated sediments and water

Frankenberger

Arshad

2001

BioFactors

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Selenium (Se) is a contaminant of agricultural irrigation-drainage water in the western United States, and the cause of wildlife deaths and grotesque deformities. Some approaches in reducing the toxic Se concentrations from contaminated sediments and water have been proposed, but most of these tend to be costly or ineffective. Bioremediation through microbial transformations of toxic Se species into nontoxic forms is being considered as an effective remedial alternative. The microbial reduction of toxic oxyanions of Se (SeO(4)(2-) and SeO(3)(2-)) into insoluble Se(0) or methylation of these species to dimethylselenide (DMSe) has been accepted as a potential bioremediation strategy for cleanup of Se-contaminated water and sediments. By conducting a series of laboratory, bench-scale and field studies, we have thoroughly investigated the remedial potential of these approaches. It was observed that microorganisms, particularly Enterobacter cloacea, are very active in reduction of Se oxyanions present in irrigation drainage water, into insoluble Se(0) and, by monitoring various environmental conditions and addition of organic amendments, the process could be stimulated manifold. Similarly, the process of biomethylation of Se in soil sediments and water was found active and highly dependent on specific carbon amendments (pectin and proteins), pH, temperature, moisture, aeration and activators (cofactors). Moreover, Se biomethylation was protein/peptide-limited rather than nitrogen-, amino acid- or carbon-limited. Crude casein and its components were equally stimulatory producing a >50-fold enhancement in DMSe yield. Methionine and methyl cobalamin stimulated DMSe production by Alternaria alternata, indicating that the coenzyme may mediate the transfer of a methyl group to the Se atom. An acute toxicity test involving inhalation of DMSe by rats revealed that DMSe is nontoxic. Experiments were scaled up from laboratory studies to field plots to verify the feasibility of this bioremediation approach. Based upon the promising results of these studies, a biotechnology prototype was developed which could be applicable for cleanup of polluted sediments and water throughout the western United States.

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Section: Methylation Of Se In Soil and Watermentioning

confidence: 99%

Bioremediation of selenium‐contaminated sediments and water

Frankenberger

Arshad

2001

BioFactors

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“…Assimilatory reduction can also occur, and several bacteria, archaea, and yeast are known to reduce

{SeO}_{3}^{2 -}

{SeO}_{4}^{2 -}

to organic Se(‐II) through Se amino acid production (Stolz, Basu, Santini, & Oremland, ; Xu et al., ). Aerobic Se(IV,VI) reduction has also been demonstrated by a number of micro‐organisms, generally as a means for detoxification, although it is substantially less studied (Barkes & Fleming, ; Bebien, Chauvin, Adriano, Grosse, & Verméglio, ; Challenger, Lisle, & Dransfield, ; Gharieb, Wilkinson, & Gadd, ; Kessi & Hanselmann, ; Schilling, Johnson, & Wilcke, ), and most publications have focused on bacterial, rather than fungal, processes. Many fungi have known metal(loid) tolerances (Gadd, ; Santelli, Chaput, & Hansel, ; Santelli et al., ; Wainwright & Gadd, ), with metal(loid) contamination often altering environmental microbial communities, in favor of fungi (Fliessbach, Martens, & Reber, ; Rajapaksha, Tobor‐Kapłon, & Bååth, ).…”

Section: Introductionmentioning

confidence: 99%

Selenium (IV,VI) reduction and tolerance by fungi in an oxic environment

et al. 2017

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Microbial processes are known to mediate selenium (Se) oxidation-reduction reactions, strongly influencing Se speciation, bioavailability, and transport throughout the environment. While these processes have commonly been studied in anaerobic bacteria, the role that aerobic fungi play in Se redox reactions could be important for Se-rich soil systems, dominated by microbial activity. We quantified fungal growth, aerobic Se(IV, VI) reduction, and Se immobilization and volatilization in the presence of six, metal-tolerant Ascomycete fungi. We found that the removal of dissolved Se was dependent on the fungal species, Se form (i.e., selenite or selenate), and Se concentration. All six species grew and removed dissolved Se(IV) or Se(VI) from solution, with five species reducing both oxyanions to Se(0) biominerals, and all six species removing at least 15%-20% of the supplied Se via volatilization. Growth rates of all fungi, however, decreased with increasing Se(IV,VI) concentrations. All fungi removed 85%-93% of the dissolved Se(IV) within 10 d in the presence of 0.01 mm Se(IV), although only about 20%-30% Se(VI) was removed when grown with 0.01 mm Se(VI). Fungi-produced biominerals were typically 50- to 300-nm-diameter amorphous or paracrystalline spherical Se(0) nanoparticles. Our results demonstrate that activity of common soil fungi can influence Se form and distribution, and these organisms may therefore play a role in detoxifying Se-polluted environments.

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“…7,8 Challenger demonstrated that S-adenosylmethionine (SAM) plays an important role in biomethylation of arsenic, and can transfer the methyl group of methionine to arsenic. 21 These findings suggest that there must be some kind of enzyme acting as the catalyst of the biomethylation reaction, which means that biological methylation is completed at the pH of the organism, which is generally close to 7. Further study is necessary to confirm which enzymes in the organism take part in the biomethylation reaction.…”

Section: Resultsmentioning

confidence: 99%

Simulate methylation reaction of arsenic(III) with methyl iodide in an aquatic system

Chen

Wang

et al. 2006

Applied Organom Chemis

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The methylation reaction of inorganic arsenic occurring in aquatic systems was studied by HPLC-HG-AFS as a method to separate and detect soluble methylarsenic species. Transformation from inorganic arsenic to methylarsenic was essential for major changes in toxicity to organisms. Monomethylarsenic [AsOCH 3 (OH) 2 ] was the only product in the methylation reaction of inorganic arsenic(III) with methyl iodide (MeI). This process can be described as an oxidative carbonium-ion transfer, with MeI acting as a methyl donor. From a thermodynamic point of view, the activity of the carbonium ion and pH were the two major influencing factors. The pH dependence of redox potential of As(III) was the reason for the effect of pH on methylation of arsenic. The influences of salinity and concentration of the methyl donor may be explained by their effects on the activity of carbonium. Moreover, kinetics experiments demonstrated that the methylation reaction was first-order for both As(III) and methyl iodide. First-order reaction rates were also calculated at different pH, salinity and MeI, and were found to be in the range 0.0026-0.0123 h −1 . The methylation rate varied largely under different reaction conditions.

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Studies on biological methylation. Part XIV. The formation of trimethylarsine and dimethyl selenide in mould cultures from methyl sources containing 14C

Cited by 46 publications

References 0 publications

Bioremediation of selenium‐contaminated sediments and water

Bioremediation of selenium‐contaminated sediments and water

Selenium (IV,VI) reduction and tolerance by fungi in an oxic environment

Simulate methylation reaction of arsenic(III) with methyl iodide in an aquatic system

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