Papers by Abdurrahman Eswayah
A wide range of microorganisms have been shown to transform selenium-containing oxyanions to redu... more A wide range of microorganisms have been shown to transform selenium-containing oxyanions to reduced forms of the element, particularly selenium-containing nanoparticles. Such reactions are promising for detoxification of environmental contamination and production of valuable selenium-containing products such as nanoparticles for application in biotechnology. It has previously been shown that aerobic methane-oxidising bacteria, including Methylococcus capsulatus (Bath), are able to perform methane-driven conversion of selenite (SeO 3 2-) to selenium-containing nanoparticles and methylated selenium species. Here, the biotransformation of selenite by Mc. capsulatus (Bath) has been studied in detail
Environmental science. Nano, 2020
The deep geological repository (DGR) system is widely accepted as the solution for the disposal o... more The deep geological repository (DGR) system is widely accepted as the solution for the disposal of radioactive wastes in the future. This concept is based on several natural and engineered barriers such as bentonite clays, which will encase the metal containers holding the radioactive waste. Microorganisms living therein can influence the mobility of the radionuclides (e.g. selenium, uranium, etc.) present in such residues. In this work the bentonite isolate Stenotrophomonas bentonitica is shown to reduce selenite (Se IV) to elemental Se (Se 0) nanostructures (amorphous and trigonal) and to volatile methylated Se −II species. Electron microscopy (HAADF-STEM) analysis of purified Se nanostructures supported the transformation process from amorphous to trigonal Se, proposed in previous studies. Infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) revealed the presence of amine rich organic matter, covering the nanostructures, suggesting the role of proteins in their synthesis and transformation. In addition, X-ray absorption spectroscopy (XAS) of SeNPs associated to the cells confirmed the formation of different Se 0 structures (amorphous and crystalline). Finally, the reduction of Se IV to volatile methylated species (DMDSe and DMSeS) was detected using a gas chromatography-mass spectrometry (GC-MS) system. The oxidation state and molecular coordination of Se in the purified Se nanostructures as well as the volatile Se species, by means of microscopic, spectroscopic, and gas chromatographic techniques, indicated their lower mobility and chemo-toxicity. This study thus highlights the potential environmental significance of microbial processes for the mobility and toxicity of selenium in future repositories, which in turn contribute to their safe implementation.
Science of The Total Environment
Social Science Research Network, 2022
The batch removal of Cu(II), Cd(II) and Pb(II) from individual heavy metal ion aqueous synthetic ... more The batch removal of Cu(II), Cd(II) and Pb(II) from individual heavy metal ion aqueous synthetic solution using biosurfactants produced by Pseudomonas aeruginosa with corn oil as substrate was investigated. The metal ion removal process of crude preparation biosurfactants (CPB) was established to be dependent on the initial pH and contact time. The optimum metal removal was observed at pH 6.0 of the initial metal solution and 10 min of contact time. The affinity sequence for metal ion removal was Pb(II)>Cd(II)>Cu(II). The removal capacity value of biosurfactant for Cu(II), Cd(II) and Pb(II) from single metal ions solution were 0.169, 0.276 and 0.323 mg/g, respectively. The removal capacity value of biosurfactant for Cu(II), Cd(II) and Pb(II) from multi metal ions solution were 0.064, 0.215 and 0.275 mg/g, respectively. The removal capacity of individual metal ion was diminished by the presence of other metal ions in multi metal ions from synthetic aqueous solution. The removal capacity value of biosurfactant for Cu(II), Cd(II) and Pb(II) from silver industry wastewater were 0.027, 0.055 and 0.291 mg/g, respectively. The results indicated that biosurfactants have potential to be used in the remediation of heavy metals in industrial wastewater.
Applied Microbiology and Biotechnology, Jun 23, 2017
Methane-oxidizing bacteria are well known for their role in the global methane cycle and their po... more Methane-oxidizing bacteria are well known for their role in the global methane cycle and their potential for microbial transformation of wide range of hydrocarbon and chlorinated hydrocarbon pollution. Recently, it has also emerged that methane-oxidizing bacteria interact with inorganic pollutants in the environment. Here, we report what we believe to be the first study of the interaction of pure strains of methane-oxidizing bacteria with selenite. Results indicate that the commonly used laboratory model strains of methaneoxidizing bacteria, Methylococcus capsulatus (Bath) and Methylosinus trichosporium OB3b, are both able to reduce the toxic selenite (SeO 3 2−) but not selenate (SeO 4 2−) to red spherical nanoparticulate elemental selenium (Se 0), which was characterized via energy-dispersive X-ray spectroscopy (EDXS), X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). The cultures also produced volatile selenium-containing species, which suggests that both strains may have an additional activity that can transform either Se 0 or selenite into volatile methylated forms of selenium. Transmission electron microscopy (TEM) measurements and experiments with the cell fractions cytoplasm, cell wall and cell membrane show that the nanoparticles are formed mainly on the cell wall. Collectively, these results are promising for the use of methane-oxidizing bacteria for bioremediation or suggest possible uses in the production of selenium nanoparticles for biotechnology.
Applied and Environmental Microbiology, 2021
M. capsulatus Bath is a well-characterized aerobic methane-oxidizing bacterium that has become a ... more M. capsulatus Bath is a well-characterized aerobic methane-oxidizing bacterium that has become a model system for biotechnological development of methanotrophs to perform useful reactions for environmental cleanup and for making valuable chemicals and biological products using methane gas. Interest in such technology has increased recently owing to increasing availability of low-cost methane from fossil and biological sources. Here, it is demonstrated that this versatile methanotroph can reduce the toxic contaminating heavy metal chromium(VI) to the less toxic form chromium(III) while accumulating the chromium(III) within the cells. This is expected to diminish the bioavailability of the chromium and make it less likely to be reoxidized to chromium(VI). Thus, M. capsulatus has the capacity to perform methane-driven remediation of chromium-contaminated water and other materials and to accumulate the chromium in the low-toxicity chromium(III) form within the cells.
Applied and Environmental Microbiology, 2019
Aerobic methane-oxidizing bacteria are ubiquitous in the environment. Two well-characterized stra... more Aerobic methane-oxidizing bacteria are ubiquitous in the environment. Two well-characterized strains, Mc . capsulatus (Bath) and Methylosinus trichosporium OB3b, representing gamma- and alphaproteobacterial methanotrophs, respectively, can convert selenite, an environmental pollutant, to volatile selenium compounds and selenium-containing particulates. Both conversions can be harnessed for the bioremediation of selenium pollution using biological or fossil methane as the feedstock, and these organisms could be used to produce selenium-containing particles for food and biotechnological applications. Using an extensive suite of techniques, we identified precursors of selenium nanoparticle formation and also found that these nanoparticles are made up of eight-membered mixed selenium and sulfur rings.
Applied microbiology and biotechnology, Jan 23, 2017
Methane-oxidizing bacteria are well known for their role in the global methane cycle and their po... more Methane-oxidizing bacteria are well known for their role in the global methane cycle and their potential for microbial transformation of wide range of hydrocarbon and chlorinated hydrocarbon pollution. Recently, it has also emerged that methane-oxidizing bacteria interact with inorganic pollutants in the environment. Here, we report what we believe to be the first study of the interaction of pure strains of methane-oxidizing bacteria with selenite. Results indicate that the commonly used laboratory model strains of methane-oxidizing bacteria, Methylococcus capsulatus (Bath) and Methylosinus trichosporium OB3b, are both able to reduce the toxic selenite (SeO3(2-)) but not selenate (SeO4(2-)) to red spherical nanoparticulate elemental selenium (Se(0)), which was characterized via energy-dispersive X-ray spectroscopy (EDXS), X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). The cultures also produced volatile selenium-containing species,...
Applied and environmental microbiology, Aug 3, 2016
Selenium species, particularly the oxyanions selenite (SeO3 (2-)) and selenate (SeO4 (2-)), are s... more Selenium species, particularly the oxyanions selenite (SeO3 (2-)) and selenate (SeO4 (2-)), are significant pollutants in the environment, which 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 twenty-first genetically encoded amino acid selenocysteine. Environmental microorganisms are known to be capable of a range of transformation of selenium species including reduction, methylation, oxidation and demethylation. Assimilatory reduction of selenium species is necessary for synthesis of selenoproteins. Dissimilatory reduction of selenate is known to support the anaerobic respiration of a number of microorganisms and the dissimilatatory reduction of soluble selenate and selenite to nanoparticulate elemental selenium greatly reduces the toxicity and bioavailability of selenium and has a major role in bio...
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Papers by Abdurrahman Eswayah