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https://www.readbyqxmd.com/read/28213734/dehalococcoides-and-general-bacterial-ecology-of-differentially-trichloroethene-dechlorinating-flow-through-columns
#1
Babur S Mirza, Darwin L Sorensen, Daniel J McGlinn, R Ryan Dupont, Joan E McLean
The diversity of Dehalococcoides mccartyi (Dhc) and/or other organohalide respiring or associated microorganisms in parallel, partial, or complete trichloroethene (TCE) dehalogenating systems has not been well described. The composition of Dhc populations and the associated bacterial community that developed over 7.5 years in the top layer (0-10 cm) of eight TCE-fed columns were examined using pyrosequencing. Columns biostimulated with one of three carbon sources, along with non-stimulated controls, developed into complete (ethene production, whey amended), partial (cis-dichloroethene (DCE) and VC, an emulsified oil with nonionic surfactant), limited (<5 % cis-DCE and 95 % TCE, an emulsified oil), and non- (controls) TCE dehalogenating systems...
February 17, 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28210952/two-dechlorinated-chlordecone-derivatives-formed-by-in-situ-chemical-reduction-are-devoid-of-genotoxicity-and-mutagenicity-and-have-lower-proangiogenic-properties-compared-to-the-parent-compound
#2
Samuel Legeay, Pierre-André Billat, Nicolas Clere, Fabrice Nesslany, Sébastien Bristeau, Sébastien Faure, Christophe Mouvet
Chlordecone (CLD) is a chlorinated hydrocarbon insecticide, now classified as a persistent organic pollutant. Several studies have previously reported that chronic exposure to CLD leads to hepatotoxicity, neurotoxicity, raises early child development and pregnancy complications, and increases the risk of liver and prostate cancer. In situ chemical reduction (ISCR) has been identified as a possible way for the remediation of soils contaminated by CLD. In the present study, the objectives were (i) to evaluate the genotoxicity and the mutagenicity of two CLD metabolites formed by ISCR, CLD-5a-hydro, or CLD-5-hydro (5a- or 5- according to CAS nomenclature; CLD-1Cl) and tri-hydroCLD (CLD-3Cl), and (ii) to explore the angiogenic properties of these molecules...
February 16, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28188205/metagenomic-and-metatranscriptomic-analyses-reveal-structure-and-dynamics-of-a-dechlorinating-community-containing-dehalococcoides-mccartyi-and-corrinoid-providing-microorganisms-under-cobalamin-limited-condition
#3
Yujie Men, Ke Yu, Jacob Bælum, Ying Gao, Julien Tremblay, Emmanuel Prestat, Ben Stenuit, Susannah G Tringe, Janet Jansson, Tong Zhang, Lisa Alvarez-Cohen
The aim of this study is to obtain a systems level understanding of the interactions between Dehalococcoides and corrinoid-supplying microorganisms by analyzing community structures and functional compositions, activities and dynamics in trichloroethene (TCE) - dechlorinating enrichments. Metagenomes and metatranscriptomes of the dechlorinating enrichments with and without exogenous cobalamin were compared. Seven putative draft genomes were binned from the metagenomes. At an early stage (2 d), more transcripts of genes in the Veillonellaceae bin-genome were detected in the metatranscriptome of the enrichment with exogenous cobalamin compared to the one without cobalamin addition...
February 10, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28159841/kinetic-mechanism-of-the-dechlorinating-flavin-dependent-monooxygenase-hada
#4
Panu Pimviriyakul, Kittisak Thotsaporn, Jeerus Sucharitakul, Pimchai Chaiyen
The accumulation of chlorophenols (CPs) in the environment, due to their wide use as agrochemicals, has become a serious environmental problem. These organic halides can be degraded by aerobic microorganisms, where the initial steps of various biodegradation pathways include an oxidative dechlorinating process in which chloride is replaced by a hydroxyl substituent. Harnessing these dechlorinating processes could provide an opportunity for environmental remediation, but detailed catalytic mechanisms for these enzymes are not yet known...
February 3, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28159790/the-effects-of-sulfate-reduction-on-tce-dechlorination-by-dehalococcoides-containing-microbial-communities
#5
Xinwei Mao, Alexandra Polasko, Lisa Alvarez-Cohen
: In order to elucidate interactions between sulfate reduction and dechlorination, we systematically evaluated the effects of different concentrations of sulfate and sulfide on reductive dechlorination by isolates, constructed consortia and enrichments containing Dehalococcoides sp. Sulfate (up to 5 mM) did not inhibit growth or metabolism of pure cultures of dechlorinator Dehalococcoides mccartyi 195, sulfate reducer Desulfovibrio vulgaris Hildenborough (DvH) or syntroph Syntrophomonas wolfei (S...
February 3, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28140362/self-catalyzed-gaas-nanowires-on-silicon-by-hydride-vapor-phase-epitaxy
#6
Zhenning Dong, Yamina André, Vladimir G Dubrovskii, Catherine Bougerol, Christine Leroux, Mohammed R Ramdani, Guillaume Monier, Agnès Trassoudaine, Dominique Castelluci, Evelyne Gil
Gold-free GaAs nanowires on silicon substrates can pave the way for monolithic integration of photonic nanodevices with silicon electronic platforms. It is extensively documented that the self-catalyzed approach works well in molecular beam epitaxy but is much more difficult to implement in vapor phase epitaxies. Here, we report the first gallium-catalyzed hydride vapor phase epitaxy growth of long (more than 10 μm) GaAs nanowires on Si(111) substrates with a high integrated growth rate up to 60 μm h(-1) and pure zincblende crystal structure...
January 31, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28135664/reductive-dechlorination-of-hexachlorobenzene-subjected-to-several-conditions-in-a-bioelectrochemical-system
#7
Hui Wang, Shuyu Yi, Xian Cao, Zhou Fang, Xianning Li
A microbial fuel cell (MFC) is a very promising way to remove organic pollutants. Hexachlorobenzene (HCB) is a widely used agricultural pesticide. In this study, single-chamber and membrane-less soil MFCs were constructed. The HCB was degraded to pentachlorobenzene (PeCB), tetrachlorobenzene (TeCB), and trichlorobenzene (TCB) in sequence by a reductive dechlorination process in soil MFCs. The influences of the external resistance, concentration of phosphate buffer, and electrode spacing in soil MFCs on the degradation rate and removal efficiency of HCB were analyzed...
January 27, 2017: Ecotoxicology and Environmental Safety
https://www.readbyqxmd.com/read/28126283/fenton-process-on-single-and-mixture-components-of-phenothiazine-pharmaceuticals-assessment-of-intermediaries-fate-and-preliminary-ecotoxicity
#8
Marcelo L Wilde, Mandy Schneider, Klaus Kümmerer
Pharmaceuticals do not occur isolated in the environment but in multi-component mixtures and may exhibit antagonist, synergistic or additive behavior. Knowledge on this is still scarce. The situation is even more complicated if effluents or potable water is treated by oxidative processes or such transformations occur in the environment. Thus, determining the fate and effects of parent compounds, metabolites and transformation products (TPs) formed by transformation and degradation processes in the environment is needed...
January 23, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28126048/dehalogenimonas-formicexedens-sp-nov-a-chlorinated-alkane-respiring-bacterium-isolated-from-contaminated-groundwater
#9
Trent A Key, Kimberly S Bowman, Imchang Lee, Jongsik Chun, Milton da Costa, Luciana Albuquerque, Fred A Rainey, William M Moe
A strictly anaerobic, Gram-stain-negative, non-spore-forming bacterium designated NSZ-14T, isolated from contaminated groundwater in Louisiana (USA), was characterized using a polyphasic approach. Strain NSZ-14T reductively dehalogenated a variety of polychlorinated aliphatic alkanes, producing ethene from 1,2-dichloroethane, propene from 1,2-dichloropropane, a mixture of cis- and trans-1,2-dichloroethene from 1,1,2,2-tetrachloroethane, vinyl chloride from 1,1,2-trichloroethane, and allyl chloride (3-chloro-1-propene) from 1,2,3-trichloropropane...
January 23, 2017: International Journal of Systematic and Evolutionary Microbiology
https://www.readbyqxmd.com/read/28112653/degradation-of-4-chlorophenol-by-mixed-fe-0-fe3o4-nanoparticles-from-the-perspective-of-mechanisms
#10
Rong Cheng, Xingyan Xue, Lei Shi, Tao Zhang, Yaping Liu, Mi Kang, Xiang Zheng
Fe(0) nanoparticles have been widely studied for pollution abatement in recent years; however, regarding the mechanism for pollutant degradation, studies have mainly focused on the reductive dechlorination by Fe(0), and the dynamic process has not been clarified completely. As reported, some organics could be degraded during the oxidation of Fe(0) by O2, and hydrogen peroxide was supposed to be produced. In this study, Fe3O4, an oxidation product of Fe(0), was used to treat the pollutant combining with Fe(0) nanoparticles, and 4-chlorophenol (4-CP) was used as the model pollutant...
January 2017: Water Science and Technology: a Journal of the International Association on Water Pollution Research
https://www.readbyqxmd.com/read/28088720/role-of-dissolved-mn-iii-in-transformation-of-organic-contaminants-non-oxidative-versus-oxidative-mechanisms
#11
Erdan Hu, Ya Zhang, Shuyan Wu, Jun Wu, Liyuan Liang, Feng He
Mn(III) is a strong oxidant for one electron transfer, which may be important in the transformation of organic contaminants during water/wastewater treatment and biogeochemical redox processes. This study explored the reaction mechanisms of dissolved Mn(III) with organics. The role of dissolved Mn(III) either as a catalyst or an oxidant in reactions with organics was recognized. Aquo and/or hydroxo (or free) Mn(III), generated from the bisulfite activated permanganate process, facilitated efficient N-dealkylation of atrazine via a β-elimination mechanism, resulting no net redox reaction...
January 7, 2017: Water Research
https://www.readbyqxmd.com/read/28087526/rapid-enrichment-of-dehalococcoides-like-bacteria-by-partial-hydrophobic-separation
#12
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/28075122/acetylene-fuels-tce-reductive-dechlorination-by-defined-dehalococcoides-pelobacter-consortia
#13
Xinwei Mao, Ronald S Oremland, Tong Liu, Sara Gushgari, Abigail A Landers, Shaun M Baesman, Lisa Alvarez-Cohen
Acetylene (C2H2) can be generated in contaminated groundwater sites as a consequence of chemical degradation of trichloroethene (TCE) by in situ minerals, and C2H2 is known to inhibit bacterial dechlorination. In this study, we show that while high C2H2 (1.3 mM) concentrations reversibly inhibit reductive dechlorination of TCE by Dehalococcoides mccartyi isolates as well as enrichment cultures containing D. mccartyi sp., low C2H2 (0.4 mM) concentrations do not inhibit growth or metabolism of D. mccartyi. Cocultures of Pelobacter SFB93, a C2H2-fermenting bacterium, with D...
February 3, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28043044/ascorbic-acid-induced-atrazine-degradation
#14
Xiaojing Hou, Xiaopeng Huang, Zhihui Ai, Jincai Zhao, Lizhi Zhang
In this study, we systematically investigated the degradation efficiency and the degradation mechanism of atrazine in the presence of ascorbic acid at different pH values. Although atrazine could be degraded by ascorbic acid in a wide pH range from 4 to 12, its degradation under either acidic (pH≤4) or alkaline (pH≥12) condition was more efficient than under neutral condition (pH=7). This pH dependent atrazine degradation was related to the reactive characteristic of atrazine and the reductive activity of ascorbic acid...
December 27, 2016: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/28038879/microbial-polychlorinated-biphenyl-dechlorination-in-sediments-by-electrical-stimulation-the-effect-of-adding-acetate-and-nonionic-surfactant
#15
Hui Yu, Hui Wan, Chunhua Feng, Xiaoyun Yi, Xiaoping Liu, Yuan Ren, Chaohai Wei
The necessity for developing an efficient and cost-effective in situ bioremediation technology for sediments contaminated with polychlorinated biphenyls (PCBs) has prompted the application of low-voltage electrical fields to anaerobic digestion systems. Here we show that the use of a sediment-based bio-electrochemical reactor (BER) poised at a potential of -0.50V (vs. a standard calomel electrode, SCE) substantially enhanced the reduction of 2,3,4,5-tetrachlorobiphenyl (PCB 61) when acetate was added as a carbon source...
December 27, 2016: Science of the Total Environment
https://www.readbyqxmd.com/read/28013464/in-situ-remediation-of-contaminated-marinesediment-an-overview
#16
G Lofrano, G Libralato, D Minetto, S De Gisi, F Todaro, B Conte, D Calabrò, L Quatraro, M Notarnicola
Sediment tends to accumulate inorganic and persistent hydrophobic organic contaminants representing one of the main sinks and sources of pollution. Generally, contaminated sediment poses medium- and long-term risks to humans and ecosystem health; dredging activities or natural resuspension phenomena (i.e., strongly adverse weather conditions) can remobilize pollution releasing it into the water column. Thus, ex situ traditional remediation activities (i.e., dredging) can be hazardous compared to in situ techniques that try to keep to a minimum sediment mobilization, unless dredging is compulsory to reach a desired bathymetric level...
December 24, 2016: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28008985/an-exceptionally-facile-two-step-structural-isomerization-and-detoxication-via-a-water-assisted-double-lossen-rearrangement
#17
Feng Li, Chun-Hua Huang, Lin-Na Xie, Na Qu, Jie Shao, Bo Shao, Ben-Zhan Zhu
N-hydroxyphthalimide (NHPI), which is best known as an organocatalyst for efficient C-H activation, has been found to be oxidized by quinoid compounds to its corresponding catalytically active nitroxide-radical. Here, we found that NHPI can be isomerized into isatoic anhydride by an unusually facile two-step method using tetrachloro-1,4-benzoquinone (TCBQ, p-chloranil), accompanied by a two-step hydrolytic dechlorination of highly toxic TCBQ into the much less toxic dihydroxylation product, 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone (chloranilic acid)...
December 23, 2016: Scientific Reports
https://www.readbyqxmd.com/read/28007851/complete-genome-sequence-of-dehalococcoides-mccartyi-strain-wbc-2-capable-of-anaerobic-reductive-dechlorination-of-vinyl-chloride
#18
Olivia Molenda, Shuiquan Tang, Elizabeth A Edwards
Dehalococcoides mccartyi strain WBC-2 dechlorinates carcinogen vinyl chloride to ethene in the West Branch Canal Creek (WBC-2) microbial consortium used for bioaugmentation. We assembled and closed the complete genome sequence of this prokaryote using metagenomic sequencing from an enrichment culture.
December 22, 2016: Genome Announcements
https://www.readbyqxmd.com/read/28004913/geochemical-parameters-and-reductive-dechlorination-determine-aerobic-cometabolic-vs-aerobic-metabolic-vinyl-chloride-biodegradation-at-oxic-anoxic-interface-of-hyporheic-zones
#19
Siavash Atashgahi, Yue Lu, Javier Ramiro-Garcia, Peng Peng, Farai Maphosa, Detmer Sipkema, Winnie Dejonghe, Hauke Smidt, Dirk Springael
Hyporheic zones mediate vinyl chloride (VC) biodegradation in groundwater discharging into surface waters. At the oxic/anoxic interface (OAI) of hyporheic zones subjected to redox oscillations, VC is degraded via coexisting aerobic ethenotrophic and anaerobic reductive dechlorination pathways. However, the identity of aerobic VC degradation pathways (cometabolic vs metabolic) and their interactions with reductive dechlorination in relation to riverbed sediment geochemistry remain ill-defined. We addressed this using microcosms containing OAI sediments incubated under fluctuating oxic/anoxic atmosphere...
January 11, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28002948/survival-of-vinyl-chloride-respiring-dehalococcoides-mccartyi-under-long-term-electron-donor-limitation
#20
Koshlan Mayer-Blackwell, Mohammad F Azizian, Jennifer K Green, Alfred M Spormann, Lewis Semprini
In anoxic groundwater aquifers, the long-term survival of Dehalococcoides mccartyi populations expressing the gene vcrA (or bvcA) encoding reductive vinyl chloride dehalogenases are important to achieve complete dechlorination of tetrachloroethene (PCE) and trichloroethene (TCE) to nonchlorinated ethene. The absence or inactivity of vcrA-containing Dehalococcoides results in the accumulation of the harmful chlorinated intermediates dichloroethene (DCE) and vinyl chloride (VC). Although vcrA-containing Dehalococcoides subpopulations depend on synergistic interaction with other organohalide-respiring populations generating their metabolic electron acceptors (DCE and VC), their survival requires successful competition for electron donor within the entire organohalide-respiring microbial community...
January 17, 2017: Environmental Science & Technology
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