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Dehalogenation

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https://www.readbyqxmd.com/read/28087526/rapid-enrichment-of-dehalococcoides-like-bacteria-by-partial-hydrophobic-separation
#1
Hanna R Temme, Kipp Sande, Tao Yan, Paige J Novak
: Organohalide respiring bacteria can be difficult to enrich and isolate, which can limit research on these important organisms. The goal of this research was to develop a method to rapidly (minutes to days) enrich these organisms from a mixed community. The method presented is based on the hypothesis that organohalide respiring bacteria would be more hydrophobic than other bacteria as they dehalogenate hydrophobic compounds. The developed method tests this hypothesis by separating a portion of putative organohalide respiring bacteria, those phylogenetically related to Dehalococcoides mccartyi, at the interface between a hydrophobic organic solvent and aqueous media...
January 13, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28068474/chemoselective-hydrodehalogenation-of-organic-halides-utilizing-two-dimensional-anionic-electrons-of-inorganic-electride-ca2n-%C3%A2-e
#2
Ye Ji Kim, Sun Min Kim, Chunghyeon Yu, Youngmin You, Eun Jin Cho, Jung Woon Yang, Sung Wng Kim
Halogenated organic compounds (HOCs) are important man-made chemicals widely used in chemical industry, biology and pharmacology; however, the persistence and inertness of organic halides cause human health problems and considerable environmental pollution. Thus, the elimination of halogen atoms from organic halides has been considered a central task in synthetic chemistry. In dehalogenation reactions, the inorganic bases remove halogen atoms, forming leaving groups and carbanions. Though the stable formation of free carbanion is the most decisive factor in determining the pathway and efficiency of reactions, the importance of carbanion stability in dehalogenation has long been overlooked...
January 9, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28035800/in-situ-generation-of-pd-pt-core-shell-nanoparticles-on-reduced-graphene-oxide-pd-pt-rgo-using-microwaves-applications-in-dehalogenation-reactions-and-reduction-of-olefins
#3
Anandarup Goswami, Anuj K Rathi, Claudia Aparicio, Ondrej Tomanec, Martin Petr, Radka Pocklanova, Manoj B Gawande, Rajender S Varma, Radek Zboril
Core-shell nanocatalysts are a distinctive class of nanomaterials with varied potential applications in view of their unique structure, composition-dependent physicochemical properties, and promising synergism among the individual components. A one-pot microwave (MW)-assisted approach is described to prepare the reduced graphene oxide (rGO)-supported Pd-Pt core-shell nanoparticles, (Pd@Pt/rGO); spherical core-shell nanomaterials (∼95 nm) with Pd core (∼80 nm) and 15 nm Pt shell were nicely distributed on the rGO matrix in view of the choice of reductant and reaction conditions...
January 11, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28034557/relative-roles-of-h-atom-transfer-and-electron-transfer-in-the-debromination-of-polybrominated-diphenyl-ethers-by-palladized-nanoscale-zerovalent-iron
#4
Rui Wang, Guining Lu, Haozhong Lin, Kaibo Huang, Ting Tang, Xiuling Xue, Xingjian Yang, Hua Yin, Zhi Dang
The relative significance of H-atom transfer versus electron transfer in the dehalogenation of halogenated organic compounds (HOCs) in bimetallic systems has long been debated. In this study, we have investigated this question through the case study of the debromination of 2, 2', 4, 4'-tetrabromodiphenyl ether (BDE-47). The debromination rates of isomer products of BDE-47 by palladized nano zero-valent iron (n-ZVI/Pd) in the same reactor were compared. The results confirmed a shift in the debromination pathway of BDE-47 when treated with unpalladized nano zero-valent iron (n-ZVI) vs...
December 26, 2016: Environmental Pollution
https://www.readbyqxmd.com/read/28034497/vertical-distribution-of-dehalogenating-bacteria-in-mangrove-sediment-and-their-potential-to-remove-polybrominated-diphenyl-ether-contamination
#5
Ying Pan, Juan Chen, Haichao Zhou, Shazia Farzana, Nora F Y Tam
The removal and degradation of polybrominated diphenyl ethers (PBDEs) in sediments are not clear. The vertical distribution of total and dehalogenating bacteria in sediment cores collected from a typical mangrove swamp in South China and their intrinsic degradation potential were investigated. These bacterial groups had the highest abundances in surface sediments (0-5cm). A 5-months microcosm experiment also showed that surface sediments had the highest rate to remove BDE-47 than deeper sediments (5-30cm) under anaerobic condition...
December 26, 2016: Marine Pollution Bulletin
https://www.readbyqxmd.com/read/28013469/bacterial-communities-associated-with-anaerobic-debromination-of-decabromodiphenyl-ether-from-mangrove-sediment
#6
Chu-Wen Yang, Ching-Chang Lee, His Ku, Bea-Ven Chang
This study evaluated decabromodiphenyl ether (BDE-209) anaerobic debromination and bacterial community changes in mangrove sediment. BDE-209 debromination rates were enhanced with zerovalent iron compared to without zerovalent iron in the sediment. BDE-209 debromination rates in microcosms constructed with sediments collected in autumn were higher than in microcosms constructed with sediments collected in spring and were higher at the Bali sampling site than the Guandu sampling site. The intermediate products resulting from the reductive debromination of BDE-209 in sediment were nona-BDE (BDE-206, BDE-207), octa-BDEs (BDE-196, BDE-197), hepta-BDEs (BDE-183, BDE-184, BDE-191), hexa-BDEs (BDE-137, BDE-138, BDE-154, BDE-157), penta-BDEs (BDE-85, BDE-99, BDE-100, BDE-126), tetra-BDEs (BDE-47, BDE-49, BDE-66, BDE-77), tri-BDEs (BDE-17, BDE-28), and di-BDEs (BDE-15)...
December 24, 2016: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/27997179/the-suzuki-miyaura-cross-coupling-reaction-of-halogenated-aminopyrazoles-method-development-scope-and-mechanism-of-dehalogenation-side-reaction
#7
Lukáš Jedinák, Renáta Zátopková, Hana Zemánková, Alena Šustková, Petr Cankař
The efficient Suzuki-Miyaura cross-coupling reaction of halogenated aminopyrazoles and their amides or ureas with a range of aryl, heteroaryl, and styryl boronic acids or esters has been developed. The method allowed incorporation of problematic substrates: aminopyrazoles bearing protected or unprotected pyrazole NH, as well as the free amino or N-amide group. Direct comparison of the chloro, bromo, and iodopyrazoles in the Suzuki-Miyaura reaction revealed that Br and Cl derivatives were superior to iodopyrazoles, as a result of reduced propensity to dehalogenation...
December 20, 2016: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/27997128/spatial-and-temporal-trends-of-polyhalogenated-carbazoles-in-sediments-of-upper-great-lakes-insights-into-their-origin
#8
Jiehong Guo, Zhuona Li, Prabha Ranasinghe, Solidea Bonina, Soheil Hosseini, Margaret B Corcoran, Colin Smalley, Karl J Rockne, Neil C Sturchio, John P Giesy, An Li
Polyhalogenated carbazoles (PHCZs) have been increasingly detected in the environment. Their similarities in chemical structure with legacy pollutants and their potential toxicity have caused increasing concern. In this work, 112 Ponar grab and 28 core sediment samples were collected from Lakes Michigan, Superior, and Huron, and a total of 26 PHCZs were analyzed along with unsubstituted carbazole using gas chromatography coupled with single- or triple-quadrupole mass spectrometry. Our results show that the total accumulation of PHCZs in the sediments of the upper Great Lakes is >3000 tonnes, orders of magnitude greater than those of polychlorinated biphenyls (PCBs) and decabromodiphenyl ether (BDE209)...
January 3, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/27974767/accessing-non-natural-reactivity-by-irradiating-nicotinamide-dependent-enzymes-with-light
#9
Megan A Emmanuel, Norman R Greenberg, Daniel G Oblinsky, Todd K Hyster
Enzymes are ideal for use in asymmetric catalysis by the chemical industry, because their chemical compositions can be tailored to a specific substrate and selectivity pattern while providing efficiencies and selectivities that surpass those of classical synthetic methods. However, enzymes are limited to reactions that are found in nature and, as such, facilitate fewer types of transformation than do other forms of catalysis. Thus, a longstanding challenge in the field of biologically mediated catalysis has been to develop enzymes with new catalytic functions...
December 14, 2016: Nature
https://www.readbyqxmd.com/read/27966913/functional-characterization-of-a-novel-amidase-involved-in-biotransformation-of-triclocarban-and-its-dehalogenated-congeners-in-ochrobactrum-sp-tcc-2
#10
Hui Yun, Bin Liang, Jiguo Qiu, Long Zhang, Youkang Zhao, Jiandong Jiang, Aijie Wang
Haloaromatic antimicrobial triclocarban (3,4,4'-trichlorocarbanilide, TCC) is a refractory contaminant which is frequently detected in various aquatic and sediment environments globally. However, few TCC-degrading communities or pure cultures have been documented, and functional enzymes involved in TCC biodegradation hitherto have not yet been characterized. In this study, a bacterial strain, Ochrobactrum sp. TCC-2, capable of degrading TCC under both aerobic and anaerobic conditions was isolated from a sediment sample...
January 3, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/27958704/photoconversion-of-chlorinated-saline-wastewater-dbps-in-receiving-seawater-is-overall-a-detoxification-process
#11
Jiaqi Liu, Xiangru Zhang, Yu Li
Chlorine disinfection of wastewater effluents rich in bromide and iodide ions results in the formation of relatively toxic bromo- and iodo-disinfection byproducts (DBPs), especially highly toxic bromophenolic and iodophenolic DBPs, which could harm the marine ecosystem when they are discharged into receiving seawater along with the wastewater effluents. In this study, we investigated the conversion of three individual halophenolic DBPs (5-bromosalicylic acid, 2,5-dibromohydroquinone, and 2,4,6-triiodophenol) and two chlorinated saline wastewater DBP mixtures in seawater...
January 3, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/27894722/impact-of-bio-palladium-nanoparticles-bio-pd-nps-on-the-activity-and-structure-of-a-marine-microbial-community
#12
Andrea Nuzzo, Baharak Hosseinkhani, Nico Boon, Giulio Zanaroli, Fabio Fava
Biogenic palladium nanoparticles (bio-Pd NPs) represent a promising catalyst for organohalide remediation in water and sediments. However, the available information regarding their possible impact in case of release into the environment, particularly on the environmental microbiota, is limited. In this study the toxicity of bio-Pd NPs on the model marine bacterium V. fischeri was assessed. The impacts of different concentrations of bio-Pd NPs on the respiratory metabolisms (i.e. organohalide respiration, sulfate reduction and methanogenesis) and the structure of a PCB-dechlorinating microbial community enriched form a marine sediment were also investigated in microcosms mimicking the actual sampling site conditions...
January 2017: Environmental Pollution
https://www.readbyqxmd.com/read/27889179/estimation-of-rate-constants-of-pcb-dechlorination-reactions-using-an-anaerobic-dehalogenation-model
#13
Filiz Karakas, Ipek Imamoglu
This study aims to estimate anaerobic dechlorination rate constants (km) of reactions of individual PCB congeners using data from four laboratory microcosms set up using sediment from Baltimore Harbor. Pathway km values are estimated by modifying a previously developed model as Anaerobic Dehalogenation Model (ADM) which can be applied to any halogenated hydrophobic organic (HOC). Improvements such as handling multiple dechlorination activities (DAs) and co-elution of congeners, incorporating constraints, using new goodness of fit evaluation led to an increase in accuracy, speed and flexibility of ADM...
February 15, 2017: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/27884059/dna-methylation-analysis-in-rat-kidney-epithelial-cells-exposed-to-3-mcpd-and-glycidol
#14
Mine Senyildiz, Buket Alpertunga, Sibel Ozden
3-Monochloropropane-1,2-diol (3-MCPD) is a well-known food processing contaminant that has been regarded as a rat carcinogen, which is known to induce Leydig-cell and mammary gland tumors in males, as well as kidney tumors in both genders. 3-MCPD is highly suspected to be a non-genotoxic carcinogen. 2,3-Epoxy-1-propanol (glycidol) can be formed via dehalogenation from 3-MCPD. We aimed to investigate the cytotoxic effects of 3-MCPD and glycidol, then to demonstrate the possible epigenetic mechanisms with global and gene-specific DNA methylation in rat kidney epithelial cells (NRK-52E)...
November 24, 2016: Drug and Chemical Toxicology
https://www.readbyqxmd.com/read/27809526/role-of-resonance-electron-attachment-in-phytoremediation-of-halogenated-herbicides
#15
Stanislav A Pshenichnyuk, Alberto Modelli, Eleonora F Lazneva, Alexei S Komolov
This study is aimed to point out the important role played by resonance electron attachment in reductive dehalogenation, in particular in phytoremediation of organic pollutants under conditions of excess negative charge. To model enzymatic reactions occurring in reductive conditions, low-energy electron capture by the halogenated herbicides atrazine and bromoxynil was studied in vacuo using electron transmission spectroscopy. A variety of decay channels of the temporary molecular negative ions was discovered by means of dissociative electron attachment spectroscopy...
December 1, 2016: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/27809258/biotransformation-of-bicyclic-halolactones-with-a-methyl-group-in-the-cyclohexane-ring-into-hydroxylactones-and-their-biological-activity
#16
Katarzyna Wińska, Małgorzata Grabarczyk, Wanda Mączka, Barbara Żarowska, Gabriela Maciejewska, Katarzyna Dancewicz, Beata Gabryś, Antoni Szumny, Mirosław Anioł
The aim of this study was the chemical synthesis of a series of halo- and unsaturated lactones, as well as their microbial transformation products. Finally some of their biological activities were assessed. Three bicyclic halolactones with a methyl group in the cyclohexane ring were obtained from the corresponding γ,δ-unsaturated ester during a two-step synthesis. These lactones were subjected to screening biotransformation using twenty two fungal strains. These strains were tested on their ability to transform halolactones into new hydroxylactones...
October 31, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/27783046/original-synthesis-of-fluorenyl-alcohol-derivatives-by-reductive-dehalogenation-initiated-by-tdae
#17
Alain Gamal Giuglio-Tonolo, Thierry Terme, Patrice Vanelle
We report here a novel and easy-to-handle reductive dehalogenation of 9-bromofluorene in the presence of arylaldehydes and dicarbonyl derivatives to give the corresponding fluorenyl alcohol derivatives and Darzens epoxides as by-products in tetrakis(dimethylamino)ethylene (TDAE) reaction conditions. The reaction is believed to proceed via two successive single electron transfers to generate the fluorenyl anion which was able to react with different electrophiles. A mechanistic study was conducted to understand the formation of the epoxide derivatives...
October 24, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/27779481/a-novel-non-opioid-binding-site-for-endomorphin-1
#18
I Lengyel, F Toth, D Biyashev, I Szatmari, K Monory, C Tomboly, G Toth, S Benyhe, A Borsodi
Endomorphins are natural amidated opioid tetrapeptides with the following structure: Tyr-Pro-Trp-Phe-NH2 (endomorphin-1), and Tyr-Pro-Phe-Phe-NH2 (endomorphin-2). Endomorphins interact selectively with the μ-opioid or MOP receptors and exhibit nanomolar or sub-nanomolar receptor binding affinities, therefore they suggested to be endogenous agonists for the μ-opioid receptors. Endomorphins mediate a number of characteristic opioid effects, such as antinociception, however there are several physiological functions in which endomorphins appear to act in a fashion that does not involve binding to and activation of the μ-opioid receptor...
August 2016: Journal of Physiology and Pharmacology: An Official Journal of the Polish Physiological Society
https://www.readbyqxmd.com/read/27766437/biological-degradation-of-4-chlorobenzoic-acid-by-a-pcb-metabolizing-bacterium-through-a-pathway-not-involving-chloro-catechol
#19
Sunday A Adebusoye
Cupriavidus sp. strain SK-3, previously isolated on polychlorinated biphenyl mixtures, was found to aerobically utilize a wide spectrum of substituted aromatic compounds including 4-fluoro-, 4-chloro- and 4-bromobenzoic acids as a sole carbon and energy source. Other chlorobenzoic acid (CBA) congeners such as 2-, 3-, 2,3-, 2,5-, 3,4- and 3,5-CBA were all rapidly transformed to respective chlorocatechols (CCs). Under aerobic conditions, strain SK-3 grew readily on 4-CBA to a maximum concentration of 5 mM above which growth became impaired and yielded no biomass...
October 20, 2016: Biodegradation
https://www.readbyqxmd.com/read/27765723/integration-of-organohalide-respiring-bacteria-and-nanoscale-zero-valent-iron-bio-nzvi-rd-a-perfect-marriage-for-the-remediation-of-organohalide-pollutants
#20
Shanquan Wang, Siyuan Chen, Yu Wang, Adrian Low, Qihong Lu, Rongliang Qiu
Due to massive production and improper handling, organohalide compounds are widely distributed in subsurface environments, primarily in anoxic groundwater, soil and sediment. Compared to traditional pump-and-treat or dredging-and-disposal treatments, in situ remediation employing abiotic or biotic reductive dehalogenation represents a sustainable and economic solution for the removal of organohalide pollutants. Both nanoscale zero-valent iron (nZVI) and organohalide-respiring bacteria remove halogens through reductive dehalogenation and have been extensively studied and successfully applied for the in situ remediation of chloroethenes and other organohalide pollutants...
October 17, 2016: Biotechnology Advances
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