Microbial Methylation Of Lead

2020 ◽  
pp. 13-20
Author(s):  
Karin Beijer ◽  
Arne Jernelöv
Keyword(s):  
Microbial Methylation

scholarly journals Microbial Methylation of Iodide in Unconfined Aquifer Sediments at the Hanford Site, USA

2019 ◽  
Vol 10 ◽  
Author(s):  
Christopher E. Bagwell ◽  
Lirong Zhong ◽  
Jacqueline R. Wells ◽  
Alexandre V. Mitroshkov ◽  
Nikolla P. Qafoku
Keyword(s):  
Unconfined Aquifer ◽  
Hanford Site ◽  
Aquifer Sediments ◽  
Microbial Methylation

scholarly journals Microbial Transformations of Selenium Species of Relevance to Bioremediation

2016 ◽  
Vol 82 (16) ◽  
pp. 4848-4859 ◽  
Author(s):  
Abdurrahman S. Eswayah ◽  
Thomas J. Smith ◽  
Philip H. E. Gardiner
Keyword(s):  
Anthropogenic Activities ◽  
Anaerobic Respiration ◽  
Reaction Rates ◽  
Elemental Selenium ◽  
Human Beings ◽  
Microbial Transformations ◽  
Selenium Species ◽  
Number Of Microorganisms ◽  
Microbial Methylation ◽  
Detoxification Process

ABSTRACTSelenium species, particularly the oxyanions selenite (SeO32−) and selenate (SeO42−), 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.

scholarly journals Microbial Methylation of Metalloids: Arsenic, Antimony, and Bismuth

2002 ◽  
Vol 66 (2) ◽  
pp. 250-271 ◽  
Author(s):  
Ronald Bentley ◽  
Thomas G. Chasteen
Keyword(s):  
Public Health ◽  
Anaerobic Bacteria ◽  
Public Health Problem ◽  
Inorganic Arsenic ◽  
Arsenic Species ◽  
Dimethylarsinic Acid ◽  
Microbial Conversion ◽  
Microbiological Test ◽  
Methylarsonic Acid ◽  
Microbial Methylation

SUMMARY 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.

scholarly journals On the methylation of inorganic mercury and the decomposition of organo-mercury compounds - a review.

1976 ◽  
Vol 24 (2) ◽  
pp. 79-97 ◽  
Author(s):  
T.M. Lexmond ◽  
F.A.M. de Haan ◽  
M.J. Frissel
Keyword(s):  
Inorganic Mercury ◽  
Anaerobic Conditions ◽  
Mercury Compounds ◽  
Laboratory Cultures ◽  
Microbial Methylation ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions ◽  
Organic Mercurials

Mercury is subjected in nature to a number of turnover reactions. The conversion of inorganic to organic forms is governed by microbial methylation which may proceed at aerobic and anaerobic conditions. Decomposition of organic mercurials may follow a chemical or a microbial pathway. The reactions and mechanisms occurring in soils, water, sediments and laboratory cultures are described. 53 references. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals Evidence of Mercury Methylation and Demethylation by the Estuarine Microbial Communities Obtained in Stable Hg Isotope Studies

2018 ◽  
Vol 15 (10) ◽  
pp. 2141 ◽  
Author(s):  
Neusa Figueiredo ◽  
Maria Serralheiro ◽  
João Canário ◽  
Aida Duarte ◽  
Holger Hintelmann ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Critical Factor ◽  
High Rate ◽  
Mercury Removal ◽  
Tagus Estuary ◽  
Simultaneous Occurrence ◽  
Mercury Methylation ◽  
Aquatic Environments ◽  
Isotope Studies ◽  
Microbial Methylation

Microbial activity is a critical factor controlling methylmercury formation in aquatic environments. Microbial communities were isolated from sediments of two highly mercury-polluted areas of the Tagus Estuary (Barreiro and Cala do Norte) and differentiated according to their dependence on oxygen into three groups: aerobic, anaerobic, and sulphate-reducing microbial communities. Their potential to methylate mercury and demethylate methylmercury was evaluated through incubation with isotope-enriched Hg species (199HgCl and CH3201HgCl). The results showed that the isolated microbial communities are actively involved in methylation and demethylation processes. The production of CH3199Hg was positively correlated with sulphate-reducing microbial communities, methylating up to 0.07% of the added 199Hg within 48 h of incubation. A high rate of CH3201Hg degradation was observed and >20% of CH3201Hg was transformed. Mercury removal of inorganic forms was also observed. The results prove the simultaneous occurrence of microbial methylation and demethylation processes and indicate that microorganisms are mainly responsible for methylmercury formation and accumulation in the polluted Tagus Estuary.

scholarly journals Experimental evidence for recovery of mercury-contaminated fish populations

Nature ◽  
2021 ◽  
Author(s):  
Paul J. Blanchfield ◽  
John W. M. Rudd ◽  
Lee E. Hrenchuk ◽  
Marc Amyot ◽  
Christopher L. Babiarz ◽  
...  
Keyword(s):  
Experimental Evidence ◽  
Aquatic Ecosystems ◽  
Wet Deposition ◽  
Fish Populations ◽  
Single Factor ◽  
Deposition Rates ◽  
Microbial Methylation ◽  
High Concentrations ◽  
Single Factor Experiment ◽  
Hg Pollution

AbstractAnthropogenic releases of mercury (Hg)1–3 are a human health issue4 because the potent toxicant methylmercury (MeHg), formed primarily by microbial methylation of inorganic Hg in aquatic ecosystems, bioaccumulates to high concentrations in fish consumed by humans5,6. Predicting the efficacy of Hg pollution controls on fish MeHg concentrations is complex because many factors influence the production and bioaccumulation of MeHg7–9. Here we conducted a 15-year whole-ecosystem, single-factor experiment to determine the magnitude and timing of reductions in fish MeHg concentrations following reductions in Hg additions to a boreal lake and its watershed. During the seven-year addition phase, we applied enriched Hg isotopes to increase local Hg wet deposition rates fivefold. The Hg isotopes became increasingly incorporated into the food web as MeHg, predominantly from additions to the lake because most of those in the watershed remained there. Thereafter, isotopic additions were stopped, resulting in an approximately 100% reduction in Hg loading to the lake. The concentration of labelled MeHg quickly decreased by up to 91% in lower trophic level organisms, initiating rapid decreases of 38–76% of MeHg concentration in large-bodied fish populations in eight years. Although Hg loading from watersheds may not decline in step with lowering deposition rates, this experiment clearly demonstrates that any reduction in Hg loadings to lakes, whether from direct deposition or runoff, will have immediate benefits to fish consumers.

Microbial methylation potential of mercury sulfide particles dictated by surface structure

2021 ◽  
Author(s):  
Li Tian ◽  
Wenyu Guan ◽  
Yunyun Ji ◽  
Xin He ◽  
Wei Chen ◽  
...  
Keyword(s):  
Surface Structure ◽  
Mercury Sulfide ◽  
Microbial Methylation

scholarly journals Arsenic Methylation and Volatilization by ArseniteS-Adenosylmethionine Methyltransferase in Pseudomonas alcaligenes NBRC14159

2015 ◽  
Vol 81 (8) ◽  
pp. 2852-2860 ◽  
Author(s):  
Jun Zhang ◽  
Tingting Cao ◽  
Zhu Tang ◽  
Qirong Shen ◽  
Barry P. Rosen ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Heterologous Expression ◽  
Main Product ◽  
Inorganic Arsenic ◽  
Biogeochemical Cycle ◽  
Content Type ◽  
Arsenic Methylation ◽  
Inorganic As ◽  
Pseudomonas Alcaligenes ◽  
Microbial Methylation

ABSTRACTInorganic arsenic (As) is highly toxic and ubiquitous in the environment. Inorganic As can be transformed by microbial methylation, which constitutes an important part of the As biogeochemical cycle. In this study, we investigated As biotransformation byPseudomonas alcaligenesNBRC14159.P. alcaligeneswas able to methylate arsenite [As(III)] rapidly to dimethylarsenate and small amounts of trimethylarsenic oxide. An arseniteS-adenosylmethionine methyltransferase, PaArsM, was identified and functionally characterized. PaArsM shares low similarities with other reported ArsM enzymes (<55%). WhenP. alcaligenes arsMgene (PaarsM) was disrupted, the mutant lost As methylation ability and became more sensitive to As(III).PaarsMwas expressed in the absence of As(III) and the expression was further enhanced by As(III) exposure. Heterologous expression ofPaarsMin an As-hypersensitive strain ofEscherichia coliconferred As(III) resistance. Purified PaArsM protein methylated As(III) to dimethylarsenate as the main product in the medium and also produced dimethylarsine and trimethylarsine gases. We propose that PaArsM plays a role in As methylation and detoxification of As(III) and could be exploited in bioremediation of As-contaminated environments.

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