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Linlin Yang, Xu Jing, Bowen An, Cheng He, Yang Yang, Chunying Duan
By synergistic combination of multicomponent self-assembly and template-directed approaches, triply interlocked metal organic catenanes that consist of two isolated chirally identical tetrahedrons were constructed and stabilized as thermodynamic minima. In the presence of suitable template anions, the structural conversion from the isolated tetrahedral conformers into locked catenanes occurred via the cleavage of an intrinsically reversible coordination bond in each of the tetrahedrons, followed by the reengineering and interlocking of two fragments with the regeneration of the broken coordination bonds...
January 28, 2018: Chemical Science
Dominique Türkowsky, Jens Esken, Tobias Goris, Torsten Schubert, Gabriele Diekert, Nico Jehmlich, Martin von Bergen
Organohalide respiration (OHR), comprising the reductive dehalogenation of halogenated organic compounds, is subject to a unique memory effect and long-term transcriptional downregulation of the involved genes in Sulfurospirillum multivorans. Gene expression ceases slowly over approximately 100 generations in the absence of tetrachloroethene (PCE). However, the molecular mechanisms of this regulation process are not understood. We show here that Sulfurospirillum halorespirans undergoes the same type of regulation when cultivated without chlorinated ethenes for a long period of time...
April 1, 2018: Journal of Proteomics
Wei Zhang, Wei Wu, Yu Long, Fushan Wang, Jiantai Ma
The design of lower-cost alternative heterogeneous catalysts for the hydrogenation of halogenated nitrobenzenes using green method to synthesize the corresponding anilines is highly desirable. In this study, Ag was incorporated into the Co-MOFs during the growing process (Co-Ag(n)-MOFs), and then followed the carbothermal reduction process without any additional procedures, we synthesized a series of Co-Ag(n)@NCs. The self-supported catalysts exhibited excellent and stable catalytic performances for the chemoselective hydrogenation of halogenated nitrobenzenes without obvious dehalogenation...
March 19, 2018: Journal of Colloid and Interface Science
Christof Holliger, Ivonne Nijenhuis
No abstract text is available yet for this article.
March 24, 2018: FEMS Microbiology Ecology
Steffi Franke, Steffen Kümmel, Ivonne Nijenhuis
RATIONALE: Halogenated benzoic acids occur in the environment due to their widespread agricultural and pharmaceutical use. Compound-specific stable isotope analysis (CSIA) has developed over the last decades for investigation of in-situ transformation and reaction mechanisms of environmental pollutants amenable by gas chromatography (GC). As polar compounds are unsuitable for GC analysis we developed a method to perform liquid chromatography (LC)/CSIA for halogenated benzoates. METHODS: LC/isotope ratio mass spectrometry (IRMS) utilizing a LC-Surveyor Pump coupled to a MAT 253 isotope ratio mass spectrometer via a LC-Isolink interface was applied...
March 25, 2018: Rapid Communications in Mass Spectrometry: RCM
Zsolt Majzik, Niko Pavliček, Manuel Vilas-Varela, Dolores Pérez, Nikolaj Moll, Enrique Guitián, Gerhard Meyer, Diego Peña, Leo Gross
Antiaromatic and open-shell molecules are attractive because of their distinct electronic and magnetic behaviour. However, their increased reactivity creates a challenge for probing their properties. Here, we describe the on-surface and in-solution generation and characterisation of a highly reactive antiaromatic molecule: indeno[1,2-b]fluorene (IF). In solution, we generated IF by KI-induced dehalogenation of a dibromo-substituted precursor molecule and found that IF survives for minutes at ambient conditions...
March 22, 2018: Nature Communications
Xi-Hui Xu, Xiao-Mei Liu, Long Zhang, Yang Mu, Xu-Yuan Zhu, Jing-Ya Fang, Shun-Peng Li, Jian-Dong Jiang
Although bioaugmentation of pollutant-contaminated sites is a great concern, there are few reports on the relationships among indigenous microbial consortia, exogenous inocula, and pollutants in a bioaugmentation process. In this study, bioaugmentation with Pseudochrobactrum sp. BSQ1 and Massilia sp. BLM18, which can hydrolytically and reductively dehalogenate chlorothalonil (TPN), respectively, was studied for its ability to remove TPN from soil; the alteration of the soil microbial community during the bioaugmentation process was investigated...
March 8, 2018: Journal of Hazardous Materials
Xuefeng Guo, Chao Yu, Zhouyang Yin, Shouheng Sun, Christopher Takakazu Seto
We report a Ni30Pd70/nitrogen-doped graphene (NG) catalyst that hydrodehalogenates halogenated aromatics under mild reaction conditions. It reduces mono- or dichloroarenes to the corresponding dehalogenated arenes in >90% yield in 10% aqueous isopropanol solvent at or below 50C within 5 hours. Tests on a variety of substrates containing various functional groups show that the catalyst is selective for reduction of C-Cl and C-Br bonds. In addition, this catalyst completely hydrodehalogenates high concentration solutions of dioxin, polychlorinated biphenyls (PCBs), chloroaromatic constituents of the defoliant agent orange, and polybrominated diphenyl ethers (PBDEs) in 12 hours...
March 14, 2018: ChemSusChem
Mingquan Yan, Zhanghao Chen, Na Li, Yuxuan Zhou, Chenyang Zhang, Gregory Korshin
This study examined the electrochemical (EC) reduction of iodinated contrast media (ICM) exemplified by iopamidol and diatrizoate. The method of rotating ring-disc electrode (RRDE) was used to elucidate rates and mechanisms of the EC reactions of the selected ICMs. Experiments were carried at varying hydrodynamic conditions, concentrations of iopamidol, diatrizoate, natural organic matter (NOM) and model compounds (resorcinol, catechol, guaiacol) which were used to examine interactions between products of the EC reduction of ICMs and halogenation-active species...
February 21, 2018: Water Research
Paul G Koster van Groos, Paul B Hatzinger, Sheryl H Streger, Simon Vainberg, R Paul Philp, Tomasz Kuder
1,2-Dibromethane (EDB) is a toxic fuel additive that likely occurs at many sites where leaded fuels have impacted groundwater. This study quantified carbon (C) isotope fractionation of EDB associated with anaerobic and aerobic biodegradation, abiotic degradation by iron sulfides, and abiotic hydrolysis. These processes likely contribute to EDB degradation in source zones (biodegradation) and in more dilute plumes (hydrolysis). Mixed anaerobic cultures containing dehalogenating organisms (e.g., Dehaloccoides spp...
March 1, 2018: Environmental Science & Technology
Qiang Sun, Xin Yu, Meiling Bao, Mengxi Liu, Jinliang Pan, Zeqi Zha, Liangliang Cai, Honghong Ma, Chunxue Yuan, Xiaohui Qiu, Wei Xu
On-surface synthesis shows significant potential in constructing novel nanostructures/nanomaterials, which has been intensely studied over the recent years. The formation of acetylenic scaffoldings provides an important route to the fabrication of emerging carbon nanostructures including carbyne, graphyne and graphdiyne, which involve the chemically vulnerable sp-hybridized carbons. Herein, we designed and synthesized a tribromomethyl group, by using the combination of high-resolution scanning tunneling microscopy and non-contact atomic force microscopy imaging and density functional theory calculations, we demonstrated that it is feasible to achieve the direct formation of C-C triple bonded structural motifs via on-surface dehalogenative homocoupling reactions...
February 20, 2018: Angewandte Chemie
Qitang Fan, Liming Liu, Jingya Dai, Tao Wang, Huanxin Ju, Jin Zhao, Julian Kuttner, Gerhard Hilt, J Michael Gottfried, Junfa Zhu
Structural transformations of supramolecular systems triggered by external stimuli maintain great potential for application in the fabrication of molecular storage devices. Using combined ultrahigh vacuum scanning tunneling microscopy (UHV-STM), X-ray photoemission spectroscopy (XPS), and density functional theory (DFT) calculation, we unambiguously observed the surface adatom mediated structural transformation from 4,4''-dibromo-m-terphenyl (DMTP)-based halogen-bonded networks to DMTP-Cu(Ag) coordination networks on Cu(111) and Ag(111) at low temperatures...
February 19, 2018: ACS Nano
Shu-Ping Zou, Kai Gu, Yu-Guo Zheng
Halohydrin dehalogenase (HHDH)-mediated dehalogenation of 1,3-dichloro-2-propanol (1,3-DCP) is a key step in the chemoenzymatic synthesis of epichlorohydrin (ECH) from glycerol. In this study, a covalent immobilization strategy was employed to enhance the stability of Agrobacterium tumefaciens HHDH by using epoxy resin ES-103B as a carrier. Under optimal conditions, the activity recovery of ES-103B-immobilized HHDH (HHDH@ES-103B) was 62.4% and the specific activity was 1604 U/g. The HHDH@ES-103B exhibited excellent thermostability, with a half-life of 68...
February 1, 2018: Biotechnology Progress
Ivonne Nijenhuis, Reiner Stollberg, Ute Lechner
The megasite Bitterfeld-Wolfen is highly contaminated as result of accidents and because of dumping of wastes from local chemical industries in the last century. A variety of contaminants including chlorinated ethenes and benzenes, hexachlorohexanes and chlorinated dioxins can still be found in the groundwater and (river) sediments. Investigations of the in situ microbial transformation of organohalides have been performed only over the last two decades at this megasite. In this review, we summarize the research on the activity of anaerobic dehalogenating bacteria at the field site in Bitterfeld-Wolfen, focusing on chlorinated ethenes, monochlorobenzene and chlorinated dioxins...
January 29, 2018: FEMS Microbiology Ecology
Kiran G Bapatla, Arjun Singh, Srujana Yeddula, Ramanagouda H Patil
The insect gut has been the house of many taxonomically and physiologically diverse groups of microbial colonizers as symbionts and commensals, which are evolving to support the physiological requirement of insects. Lepidoptera is one of the important family of class hexapoda, comprising agriculture insect pest Spodoptera litura and Spilosoma obliqua. Information on gut microbiota and their functional role in these insects was meager to elucidate the wide-ranging survivalist mechanisms. In this context, we analyzed the composition, diversity and functional role of gut bacteria in S...
January 30, 2018: Journal of Basic Microbiology
Bat-Erdene Jugder, Karl A P Payne, Karl Fisher, Susanne Bohl, Helene Lebhar, Mike Manefield, Matthew Lee, David Leys, Christopher P Marquis
Reductive dehalogenases (RDases) are key enzymes involved in the respiratory process of anaerobic organohalide respiring bacteria (ORB). Heterologous expression of respiratory RDases is desirable for structural and functional studies; however, there are few reports of successful expression of these enzymes. Dehalobacter sp. strain UNSWDHB is an ORB, whose preferred electron acceptor is chloroform. This study describes efforts to express recombinant reductive dehalogenase (TmrA), derived from UNSW DHB, using the heterologous hosts Escherichia coli and Bacillus megaterium...
March 16, 2018: ACS Chemical Biology
Yayue Wang, Yanbin Feng, Xupeng Cao, Yinghui Liu, Song Xue
D-2-haloacid dehalogenases (D-DEXs) catalyse the hydrolytic dehalogenation of D-2-haloacids, releasing halide ions and producing the corresponding 2-hydroxyacids. A structure-guided elucidation of the catalytic mechanism of this dehalogenation reaction has not been reported yet. Here, we report the catalytic mechanism of a D-DEX, HadD AJ1 from Pseudomonas putida AJ1/23, which was elucidated by X-ray crystallographic analysis and the H2 18 O incorporation experiment. HadD AJ1 is an α-helical hydrolase that forms a homotetramer with its monomer including two structurally axisymmetric repeats...
January 23, 2018: Scientific Reports
Mara R de Lima E Silva, Regiane C Correa, Isabel K Sakamoto, Maria B A Varesche
Recent papers have confirmed current environmental pollution and the continuous release of polychlorinated biphenyls (PCBs) despite the prohibition of its manufacture worldwide. As the dehalogenating microorganisms are able to remove halogens from various analogous compounds, the characterization of PCB metabolisms can improve the degradation of similar compounds. Thus, this study extensively evaluated the microbial community developed in methanogenic and iron-reducing reactors. The horizontal-flow anaerobic reactor (HAIB) with real waste of Aroclor (1 mL L-1) was fed with mineral medium, ethanol, and sodium formate...
January 17, 2018: Current Microbiology
Tassia C Egea, Roberto da Silva, Maurício Boscolo, Janaina Rigonato, Diego A Monteiro, Danilo Grünig, Humberto da Silva, Frans van der Wielen, Rick Helmus, John R Parsons, Eleni Gomes
The isolation of microorganisms from soil impacted by xenobiotic chemicals and exposing them in the laboratory to the contaminant can provide important information about their response to the contaminants. The purpose of this study was to isolate bacteria from soil with historical application of herbicides and to evaluate their potential to degrade diuron. The isolation media contained either glucose or diuron as carbon source. A total of 400 bacteria were isolated, with 68% being Gram-positive and 32% Gram-negative...
December 2017: Heliyon
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