Microbiological Methylation of Arsenic

Cox, D.P.

doi:10.1021/bk-1975-0007.ch006

Cited by 25 publications

(15 citation statements)

References 6 publications

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“…Only a brief account will be given here since two authoritative reviews are available (52,75). All of the organic As(V) compounds of the Challenger pathway (methylarsonate, dimethylarsinate, trimethylarsine oxide) have been observed in cell extracts metabolizing arsenate, and all of them are precursors for trimethylarsine biosynthesis (70,195).…”

Section: Fungi and Yeastsmentioning

confidence: 99%

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Microbial Methylation of Metalloids: Arsenic, Antimony, and Bismuth

Bentley

Chasteen

2002

Microbiol Mol Biol Rev

515

316

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A significant 19th century public health problem was that the inhabitants of many houses containing wallpaper decorated with green arsenical pigments experienced illness and death. The problem was caused by certain fungi that grew in the presence of inorganic arsenic to form a toxic, garlic-odored gas. The garlic odor was actually put to use in a very delicate microbiological test for arsenic. In 1933, the gas was shown to be trimethylarsine. It was not until 1971 that arsenic methylation by bacteria was demonstrated. Further research in biomethylation has been facilitated by the development of delicate techniques for the determination of arsenic species. As described in this review, many microorganisms (bacteria, fungi, and yeasts) and animals are now known to biomethylate arsenic, forming both volatile (e.g., methylarsines) and nonvolatile (e.g., methylarsonic acid and dimethylarsinic acid) compounds. The enzymatic mechanisms for this biomethylation are discussed. The microbial conversion of sodium arsenate to trimethylarsine proceeds by alternate reduction and methylation steps, with S-adenosylmethionine as the usual methyl donor. Thiols have important roles in the reductions. In anaerobic bacteria, methylcobalamin may be the donor. The other metalloid elements of the periodic table group 15, antimony and bismuth, also undergo biomethylation to some extent. Trimethylstibine formation by microorganisms is now well established, but this process apparently does not occur in animals. Formation of trimethylbismuth by microorganisms has been reported in a few cases. Microbial methylation plays important roles in the biogeochemical cycling of these metalloid elements and possibly in their detoxification. The wheel has come full circle, and public health considerations are again important

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Section: Fungi and Yeastsmentioning

confidence: 99%

“…Sodium salts of selenite and selenate were also strongly inhibitory, and sodium tellurate was a moderate inhibitor. C. humiculus is known to methylate both selenate and selenite to dimethylselenide (52).…”

Section: Fungi and Yeastsmentioning

confidence: 99%

Microbial Methylation of Metalloids: Arsenic, Antimony, and Bismuth

Bentley

Chasteen

2002

Microbiol Mol Biol Rev

515

316

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“…of As were'first recognized in the early nineteenth century (Cox, 1975;Epps and Sturgis, 1939;Fleischer, 1973). Wood (1974) pointed out that, in the reduced environment such as flooded soils, arsenate is reduced to arsine and then methylated to form methylarsenic acid forms.…”

Section: Biological Transformations Of As In Soilsmentioning

confidence: 99%

Arsenic chemistry in soils: An overview of thermodynamic predictions and field observations

Sadiq

1997

Water Air Soil Pollut

363

223

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Abstract, Published information, both theoretical and experimental, on As chemical behavior in soils is reviewed. Because of many emission sources, As is ubiquitous. Thermodynamic calculations revealed that As(V) species (HAsO~->H2AsQ-at pH 7) are more abundant in soil solutions that are oxidized more than pe+pH>9. Arsenic is expected to be in As(III) form (HAsO ~ = H3AsO~ = H2AsO~-at pH 7) in relatively anoxic soil solutions with pe+pH<7.Adsorption on soil colloids is an important As scavenging mechanism. The adsorption capacity and behavior of these colloids (clay, oxides or hydroxides surfaces of AI, Fe and Mn, calcium carbonates, and/or organic matter) are dependent on ever-changing factors, such as hydration, soil pH, specific adsorption, changes in cation coordination, isomorphous replacement, crystallinity, etc. Because of the altering tendencies of soil colloids properties, adsorption of As has become a complex, empirical, ambiguous, and often a self contradicting process in soils. In general, Fe oxides/hydroxides are the most commonly involved in the adsorption of As in both acidic and alkaline soils. The surfaces of AI oxides/hydroxides and clay may play a role in As adsorption, but only in acidic soils. The carbonate minerals are expected to adsorb As in calcareous soils. The role of Mn oxides and biogenic particles in the As adsorption in soils appears to be limited to acidic soils. Kinetically, As adsorption may reach over 90% completion in terms of hours.Precipitation of a solid phase is another mechanism of As removal from soil solutions. Thermodynamic calculations showed that in the acidic oxic and suboxic soils, Fe-arsenate (Fe3(AsO4)2) may control As solubility, whereas in the anoxic soils, sulfides of As(IIl) may control the concentrations of the dissolved As in soil solutions. In alkaline acidic oxic and suboxic soils, precipitation of both Fe-and Ca-arsenate may limit As concentrations in soil solutions.Field observations suggest that direct precipitation of discrete As solid phases may not occur, except in contaminated soils. Chemisorption of As oxyanions on soil colloid surfaces, especially those of Fe oxide/hydroxides and carbonates, is believed to a common mechanisms for As solid phase formation in soils. It is suggested that As oxyanions gradually concentrate on colloid surfaces to a level high enough to precipitate a discrete or mixed As solid phase.Arsenic volatilization is another As scavenging mechanism operating in soils. Many soil organisms are capable of converting arsenate and arsenite to several reduced forms, largely methylated arsines which are volatile. These organisms may generate different or similar biochemical products. Methylation and volatilization of As can be affected by several biotic (such as type of organisms, ability of organism for methylation, etc.) and abiotic factors (soil pH, temperature, redox conditions, methyl donor, presence of other ions, etc.) factors. Information on the rate of As biotransformations in soils is limited. In comparison to the biologicall...

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“…Chalenger and Higginbottom 8 showed that the fungus Scopulariopsis brevicaulus could produce TMA from arsenite. Subsequent work 9,10 confirmed that other fungi, such as Penicillium sp., Gliocladium reseum and the yeast, Candida humicola, were also capable of arsenic biomethylation. Transformation of arsenic compounds to less toxic forms can help remove toxic arsenic from the environment.…”

Section: Introductionmentioning

confidence: 91%

Untitled

Visoottiviseth¹,

Panviroj²

2001

ScienceAsia

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Thirty eight fungal isolates that grew in 700 mg l -1 of either arsenite or arsenate medium were isolated from soil samples collected from arsenic-polluted areas in Ron Phibun District, Nakhon Si Thammarat Province, Thailand. Out of these, the fungal isolate (RRMT2-40I) was the most efficient at removing arsenite/arsenate from potato dextrose broth. This fungus, identified as Penicillium sp., grew best in growth medium with a pH of 5.0 or 7.0 at 27 o C, reaching the stationary growth phase within 4 days. Its growth was slightly affected by arsenite/arsenate concentrations of 1000 mg l -1 in the medium, but lower concentrations (10 and 100 mg l -1 ) had no effect. Arsenic uptake exhibited a peak and turning point at the stationary growth phase. During this phase, arsenic was excreted from the fungal cells. Arsenic removal depended on culture age and cell viability since there was no arsenite/arsenate removal when the cells were killed by autoclaving.

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Microbiological Methylation of Arsenic

Cited by 25 publications

References 6 publications

Microbial Methylation of Metalloids: Arsenic, Antimony, and Bismuth

Microbial Methylation of Metalloids: Arsenic, Antimony, and Bismuth

Arsenic chemistry in soils: An overview of thermodynamic predictions and field observations

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