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Precise Regulation of Differential Transcriptions of Various Catabolic Genes by OdcR via a Single Nucleotide Mutation in the Promoter Ensures the Safety of Metabolic Flux. Appl Environ Microbiol 2022; 88:e0118222. [PMID: 36036586 PMCID: PMC9499029 DOI: 10.1128/aem.01182-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Synergistic regulation of the expression of various genes in a catabolic pathway is crucial for the degradation, survival, and adaptation of microorganisms in polluted environments. However, how a single regulator accurately regulates and controls differential transcriptions of various catabolic genes to ensure metabolic safety remains largely unknown. Here, a LysR-type transcriptional regulator (LTTR), OdcR, encoded by the regulator gene odcR, was confirmed to be essential for 3,5-dibromo-4-hydroxybenozate (DBHB) catabolism and simultaneously activated the transcriptions of a gene with unknown function, orf419, and three genes, odcA, odcB, and odcC, involved in the DBHB catabolism in Pigmentiphaga sp. strain H8. OdcB further metabolized the highly toxic intermediate 2,6-dibromohydroquinone, which was produced from DBHB by OdcA. The upregulated transcriptional level of odcB was 7- to 9-fold higher than that of orf419, odcA, or odcC in response to DBHB. Through an electrophoretic mobility shift assay and DNase I footprinting assay, DBHB was found to be the effector and essential for OdcR binding to all four promoters of orf419, odcA, odcB, and odcC. A single nucleotide mutation in the regulatory binding site (RBS) of the promoter of odcB (TAT-N11-ATG), compared to those of odcA/orf419 (CAT-N11-ATG) and odcC (CAT-N11-ATT), was identified and shown to enable the significantly higher transcription of odcB. The precise regulation of these genes by OdcR via a single nucleotide mutation in the promoter avoided the accumulation of 2,6-dibromohydroquinone, ensuring the metabolic safety of DBHB. IMPORTANCE Prokaryotes use various mechanisms, including improvement of the activity of detoxification enzymes, to cope with toxic intermediates produced during catabolism. However, studies on how bacteria accurately regulate differential transcriptions of various catabolic genes via a single regulator to ensure metabolic safety are scarce. This study revealed a LysR-type transcriptional activator, OdcR, which strongly activated odcB transcription for the detoxification of the toxic intermediate 2,6-dibromohydroquinone and slightly activated the transcriptions of other genes (orf419, odcA, and odcC) for 3,5-dibromo-4-hydroxybenozate (DBHB) catabolism in Pigmentiphaga sp. strain H8. Interestingly, the differential transcription/expression of the four genes, which ensured the metabolic safety of DBHB in cells, was determined by a single nucleotide mutation in the regulatory binding sites of the four promoters. This study describes a new and ingenious regulatory mode of ensuring metabolic safety in bacteria, expanding our understanding of synergistic transcriptional regulation in prokaryotes.
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Baygi SF, Fernando S, Hopke PK, Holsen TM, Crimmins BS. Nontargeted Discovery of Novel Contaminants in the Great Lakes Region: A Comparison of Fish Fillets and Fish Consumers. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:3765-3774. [PMID: 33646760 DOI: 10.1021/acs.est.0c08507] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Sport fish fillets and human sera (fish consumers) were collected in the Lake Superior and Lake Michigan basin and screened for novel contaminants using the isotopic profile deconvoluted chromatogram (IPDC) algorithm. The IPDC algorithm was extended beyond traditional Cl/Br filters to detect additional potential bioaccumulative and toxic (PBT) such as perfluoroalkyl substances (PFAS). The IPDC algorithm screened for approximately 13.5 million theoretical molecular formulas. Additional algorithm modules were developed to detect data independent MS/MS fragmentation products and a retention time index calculator using a series of 13C-labeled perfluoroalkyl carboxylic acids (13C-PFCAs). Ten potential compound classes were isolated including six untargeted PFAS, six homologue groups of polyfluorinated carboxylic acids, polyfluorinated telomer alcohols (PoFTOHs), two hydroxylated polychlorobiphenyls, pesticides, herbicides, antifungals, pharmaceuticals, artificial sweeteners, and personal care products with minimal postprocessing efforts. The algorithm isolated 48 ubiquitous PoFTOHs in both fish fillet and serum of fish consumers suggesting a region wide distribution of this class of compounds. The 3, 4, and 7 fluorine substituted PoFTOH were the most abundant congeners in both biological matrices.
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Affiliation(s)
- Sadjad Fakouri Baygi
- Clarkson University, Department of Chemical and Biomolecular Engineering, 8 Clarkson Avenue, Potsdam, New York 13699, United States
| | - Sujan Fernando
- Clarkson University, Center for Air Resources Engineering and Science, 8 Clarkson Avenue, Potsdam, New York 13699, United States
| | - Philip K Hopke
- Clarkson University, Department of Chemical and Biomolecular Engineering, 8 Clarkson Avenue, Potsdam, New York 13699, United States
| | - Thomas M Holsen
- Clarkson University, Center for Air Resources Engineering and Science, 8 Clarkson Avenue, Potsdam, New York 13699, United States
- Clarkson University, Department of Civil and Environmental Engineering, 8 Clarkson Avenue, Potsdam, New York 13699, United States
| | - Bernard S Crimmins
- Clarkson University, Department of Civil and Environmental Engineering, 8 Clarkson Avenue, Potsdam, New York 13699, United States
- AEACS, LLC, New Kensington, Pennsylvania 15068, United States
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Knossow N, Siebner H, Bernstein A. Isotope analysis method for the herbicide bromoxynil and its application to study photo-degradation processes. JOURNAL OF HAZARDOUS MATERIALS 2020; 388:122036. [PMID: 31951995 DOI: 10.1016/j.jhazmat.2020.122036] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 12/29/2019] [Accepted: 01/06/2020] [Indexed: 06/10/2023]
Abstract
Bromoxynil is an increasingly applied nitrile herbicide used for post-emergent control of annual broadleaved weeds. Compound-specific isotope analysis (CSIA) of the compound is of interest for studying its environmental fate, yet is challenging following its polar nature. We present a CSIA method for bromoxynil that includes offline thin-layer chromatography purification followed by an elemental analyzer isotope ratio mass spectrometer (EA-IRMS). This method was shown to be accurate and precise for δ13C and δ15N analysis of the compound (standard deviation of replicate standards <0.5‰). The method was applied to photodegraded samples, either radiated under laboratory condition with a UV lamp, or exposed to sunlight under environmental conditions. Dominating degradation products were similar in both cases. Nevertheless, isotope effects differed, presenting a strong inverse carbon isotope effect (εC = 4.74 ± 0.82‰) and a weak inverse nitrogen isotope effect (εN = 0.76 ± 0.12‰) for the laboratory experiment, and an insignificant carbon isotope effect (εC = 0.34 ± 0.44‰) and a normal nitrogen isotope effect (εN = -3.70 ± 0.30‰) for the natural conditions experiment. The differences in δ13C vs. δ15N enrichment trends suggest different mechanism for the two processes. Finally, the obtained dual isotope trend for natural conditions provide the basis for studying the dominance of photodegradation as a degradation route in the environment.
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Affiliation(s)
- Nadav Knossow
- Zuckerberg Institute for Water Research, Department of Environmental Hydrology and Microbiology, Ben-Gurion University of the Negev, Sede Boqer Campus, 8499000, Israel
| | - Hagar Siebner
- Zuckerberg Institute for Water Research, Department of Environmental Hydrology and Microbiology, Ben-Gurion University of the Negev, Sede Boqer Campus, 8499000, Israel
| | - Anat Bernstein
- Zuckerberg Institute for Water Research, Department of Environmental Hydrology and Microbiology, Ben-Gurion University of the Negev, Sede Boqer Campus, 8499000, Israel.
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4
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Knossow N, Siebner H, Bernstein A. Isotope Fractionation (δ 13C, δ 15N) in the Microbial Degradation of Bromoxynil by Aerobic and Anaerobic Soil Enrichment Cultures. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2020; 68:1546-1554. [PMID: 31986047 DOI: 10.1021/acs.jafc.9b07653] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Bromoxynil is an increasingly applied nitrile herbicide. Under aerobic conditions, hydration, nitrilation, or hydroxylation of the nitrile group commonly occurs, whereas under anaerobic conditions reductive dehalogenation is common. This work studied the isotope effects associated with these processes by soil cultures. The aerobic soil enrichment culture presented a significant increase in Stenotrophomonas, Pseudomonas, Chryseobacterium, Achromobacter, Azospirillum, and Arcticibacter, and degradation products indicated that nitrile hydratase was the dominant degradation route. The anaerobic culture was dominated by Proteobacteria and Firmicutes phyla with a significant increase in Dethiosulfatibacter, and degradation products indicated reductive debromination as a major degradation route. Distinct dual-isotope trends (δ13C, δ15N) were determined for the two routes: a strong inverse nitrogen isotope effect (εN = 10.56 ± 0.36‰) and an insignificant carbon isotope effect (εC = 0.37 ± 0.36‰) for the aerobic process versus a negligible effect for both elements in the anaerobic process. These trends differ from formerly reported trends for the photodegradation of bromoxynil and enable one to distinguish between the processes in the field.
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Affiliation(s)
- Nadav Knossow
- Zuckerberg Institute for Water Research, Department of Environmental Hydrology and Microbiology , Ben-Gurion University of the Negev , Sede Boqer Campus , Sede Boqer 8499000 , Israel
| | - Hagar Siebner
- Zuckerberg Institute for Water Research, Department of Environmental Hydrology and Microbiology , Ben-Gurion University of the Negev , Sede Boqer Campus , Sede Boqer 8499000 , Israel
| | - Anat Bernstein
- Zuckerberg Institute for Water Research, Department of Environmental Hydrology and Microbiology , Ben-Gurion University of the Negev , Sede Boqer Campus , Sede Boqer 8499000 , Israel
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Sims GK, Kanissery RG. Anaerobic Biodegradation of Pesticides. MICROORGANISMS FOR SUSTAINABILITY 2019. [DOI: 10.1007/978-981-13-7462-3_2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Collins FA, Fisher K, Payne KAP, Gaytan Mondragon S, Rigby SEJ, Leys D. NADPH-Driven Organohalide Reduction by a Nonrespiratory Reductive Dehalogenase. Biochemistry 2018; 57:3493-3502. [PMID: 29630828 DOI: 10.1021/acs.biochem.8b00255] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Reductive dehalogenases are corrinoid and iron-sulfur cluster-dependent enzymes that mostly act as the terminal oxidoreductases in the bacterial organohalide respiration process. This process often leads to detoxification of recalcitrant organohalide pollutants. While low cell yields and oxygen sensitivity hamper the study of many reductive dehalogenases, this is not the case for the nonrespiratory reductive dehalogenase NpRdhA from Nitratireductor pacificus. We here report in vitro and in vivo reconstitution of an NADPH-dependent reducing system for NpRdhA. Surprisingly, NpRdhA mediated organohalide reduction could not be supported using N. pacificus ferredoxin-NAD(P)H oxidoreductase and associated ferredoxins. Instead, we found a nonphysiological system comprised of the Escherichia coli flavodoxin reductase (EcFldr) in combination with spinach ferredoxin (SpFd) was able to support NADPH-dependent organohalide reduction by NpRdhA. Using this system, organohalide reduction can be performed under both anaerobic and aerobic conditions, with 1.1 ± 0.1 and 3.5 ± 0.3 equiv of NADPH consumed per product produced, respectively. No significant enzyme inactivation under aerobic conditions was observed, suggesting a Co(I) species is unlikely to be present under steady state conditions. Furthermore, reduction of the Co(II) resting state was not observed in the absence of substrate. Only the coexpression of EcFldr, SpFd, and NpRdhA in Bacillus megaterium conferred the latter with the ability to reduce brominated NpRdhA substrates in vivo, in agreement with our in vitro observations. Our work provides new insights into biological reductive dehalogenase reduction and establishes a blueprint for the minimal functional organohalide reduction module required for bioremediation in situ.
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Affiliation(s)
- Fraser A Collins
- Manchester Institute of Biotechnology , University of Manchester , 131 Princess Street , Manchester M1 7DN , U.K
| | - Karl Fisher
- Manchester Institute of Biotechnology , University of Manchester , 131 Princess Street , Manchester M1 7DN , U.K
| | - Karl A P Payne
- Manchester Institute of Biotechnology , University of Manchester , 131 Princess Street , Manchester M1 7DN , U.K
| | - Samantha Gaytan Mondragon
- Manchester Institute of Biotechnology , University of Manchester , 131 Princess Street , Manchester M1 7DN , U.K
| | - Stephen E J Rigby
- Manchester Institute of Biotechnology , University of Manchester , 131 Princess Street , Manchester M1 7DN , U.K
| | - David Leys
- Manchester Institute of Biotechnology , University of Manchester , 131 Princess Street , Manchester M1 7DN , U.K
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El-Sayed WS. Characterization of a Highly Enriched Microbial Consortium Reductively Dechlorinating 2,3-Dichlorophenol and 2,4,6-Trichlorophenol and the Corresponding cprA Genes from River Sediment. Pol J Microbiol 2018; 65:341-352. [PMID: 29334051 DOI: 10.5604/17331331.1215613] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Anaerobic reductive dechlorination of 2,3-dichlorophenol (2,3DCP) and 2,4,6-trichlorophenol (2,4,6TCP) was investigated in microcosms from River Nile sediment. A stable sediment-free anaerobic microbial consortium reductively dechlorinating 2,3DCP and 2,4,6TCP was established. Defined sediment-free cultures showing stable dechlorination were restricted to ortho chlorine when enriched with hydrogen as the electron donor, acetate as the carbon source, and either 2,3-DCP or 2,4,6-TCP as electron acceptors. When acetate, formate, or pyruvate were used as electron donors, dechlorination activity was lost. Only lactate can replace dihydrogen as an electron donor. However, the dechlorination potential was decreased after successive transfers. To reveal chlororespiring species, the microbial community structure of chlorophenol-reductive dechlorinating enrichment cultures was analyzed by PCR-denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments. Eight dominant bacteria were detected in the dechlorinating microcosms including members of the genera Citrobacter, Geobacter, Pseudomonas, Desulfitobacterium, Desulfovibrio and Clostridium. Highly enriched dechlorinating cultures were dominated by four bacterial species belonging to the genera Pseudomonas, Desulfitobacterium, and Clostridium. Desulfitobacterium represented the major fraction in DGGE profiles indicating its importance in dechlorination activity, which was further confirmed by its absence resulting in complete loss of dechlorination. Reductive dechlorination was confirmed by the stoichiometric dechlorination of 2,3DCP and 2,4,6TCP to metabolites with less chloride groups and by the detection of chlorophenol RD cprA gene fragments in dechlorinating cultures. PCR amplified cprA gene fragments were cloned and sequenced and found to cluster with the cprA/pceA type genes of Dehalobacter restrictus.
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Affiliation(s)
- Wael S El-Sayed
- Biology Department, Faculty of Science, Taibah University, Almadinah Almunawarah, KSA; Microbiology Department, Faculty of Science, Ain Shams University, Cairo, Egypt
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Pshenichnyuk SA, Modelli A, Komolov AS. Interconnections between dissociative electron attachment and electron-driven biological processes. INT REV PHYS CHEM 2018. [DOI: 10.1080/0144235x.2018.1461347] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Stanislav A. Pshenichnyuk
- Institute of Molecule and Crystal Physics – Subdivision of the Ufa Research Centre of the Russian Academy of Sciences, Ufa, Russia
| | - Alberto Modelli
- Dipartimento di Chimica ‘G. Ciamician’, Università di Bologna, Bologna, Italy
- Centro Interdipartimentale di Ricerca in Scienze Ambientali, Ravenna, Italy
| | - Alexei S. Komolov
- Department of Solid State Electronics, St. Petersburg State University, St. Petersburg, Russia
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Comparative Transcriptome Analysis Reveals the Mechanism Underlying 3,5-Dibromo-4-Hydroxybenzoate Catabolism via a New Oxidative Decarboxylation Pathway. Appl Environ Microbiol 2018; 84:AEM.02467-17. [PMID: 29305508 DOI: 10.1128/aem.02467-17] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 12/13/2017] [Indexed: 02/07/2023] Open
Abstract
The compound 3,5-dibromo-4-hydroxybenzoate (DBHB) is both anthropogenically released into and naturally produced in the environment, and its environmental fate is of great concern. Aerobic and anaerobic reductive dehalogenations are the only two reported pathways for DBHB catabolism. In this study, a new oxidative decarboxylation pathway for DBHB catabolism was identified in a DBHB-utilizing strain, Pigmentiphaga sp. strain H8. The genetic determinants underlying this pathway were elucidated based on comparative transcriptome analysis and subsequent experimental validation. A gene cluster comprising orf420 to orf426, with transcripts that were about 33- to 4,400-fold upregulated in DBHB-induced cells compared with those in uninduced cells, was suspected to be involved in DBHB catabolism. The gene odcA (orf420), which is essential for the initial catabolism of DBHB, encodes a novel NAD(P)H-dependent flavin monooxygenase that mediates the oxidative decarboxylation of DBHB to 2,6-dibromohydroquinone (2,6-DBHQ). The substrate specificity of the purified OdcA indicated that the 4-hydroxyl group and its ortho-halogen(s) are important for hydroxylation of the C-1 site carboxyl group by OdcA. 2,6-DBHQ is then ring cleaved by the dioxygenase OdcB (Orf425) to 2-bromomaleylacetate, which is finally transformed to β-ketoadipate by the maleylacetate reductase OdcC (Orf426). These results provide a better understanding of the molecular mechanism underlying the catabolic diversity of halogenated para-hydroxybenzoates.IMPORTANCE Halogenated hydroxybenzoates (HBs), which are widely used synthetic precursors for chemical products and common metabolic intermediates from halogenated aromatics, exert considerable adverse effects on human health and ecological security. Microbial catabolism plays key roles in the dissipation of halogenated HBs in the environment. In this study, the discovery of a new catabolic pathway for 3,5-dibromo-4-hydroxybenzoate (DBHB) and clarification of the genetic determinants underlying the pathway broaden our knowledge of the catabolic diversity of halogenated HBs in microorganisms. Furthermore, the NAD(P)H-dependent flavin monooxygenase OdcA identified in Pigmentiphaga sp. strain H8 represents a novel 1-monooxygenase for halogenated para-HBs found in prokaryotes and enhances our knowledge of the decarboxylative hydroxylation of (halogenated) para-HBs.
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Oliveira KO, Silva AR, da Silva BF, Milagre HM, Milagre CD. Insights into the microbial degradation pathways of the ioxynil octanoate herbicide. BIOCATALYSIS AND AGRICULTURAL BIOTECHNOLOGY 2018. [DOI: 10.1016/j.bcab.2018.01.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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11
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Huang X, He J, Yan X, Hong Q, Chen K, He Q, Zhang L, Liu X, Chuang S, Li S, Jiang J. Microbial catabolism of chemical herbicides: Microbial resources, metabolic pathways and catabolic genes. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2017; 143:272-297. [PMID: 29183604 DOI: 10.1016/j.pestbp.2016.11.010] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Revised: 11/21/2016] [Accepted: 11/23/2016] [Indexed: 06/07/2023]
Abstract
Chemical herbicides are widely used to control weeds and are frequently detected as contaminants in the environment. Due to their toxicity, the environmental fate of herbicides is of great concern. Microbial catabolism is considered the major pathway for the dissipation of herbicides in the environment. In recent decades, there have been an increasing number of reports on the catabolism of various herbicides by microorganisms. This review presents an overview of the recent advances in the microbial catabolism of various herbicides, including phenoxyacetic acid, chlorinated benzoic acid, diphenyl ether, tetra-substituted benzene, sulfonamide, imidazolinone, aryloxyphenoxypropionate, phenylurea, dinitroaniline, s-triazine, chloroacetanilide, organophosphorus, thiocarbamate, trazinone, triketone, pyrimidinylthiobenzoate, benzonitrile, isoxazole and bipyridinium herbicides. This review highlights the microbial resources that are capable of catabolizing these herbicides and the mechanisms involved in the catabolism. Furthermore, the application of herbicide-degrading strains to clean up herbicide-contaminated sites and the construction of genetically modified herbicide-resistant crops are discussed.
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Affiliation(s)
- Xing Huang
- Department of Microbiology, Key Lab of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, People's Republic of China
| | - Jian He
- Department of Microbiology, Key Lab of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, People's Republic of China
| | - Xin Yan
- Department of Microbiology, Key Lab of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, People's Republic of China
| | - Qing Hong
- Department of Microbiology, Key Lab of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, People's Republic of China
| | - Kai Chen
- Department of Microbiology, Key Lab of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, People's Republic of China
| | - Qin He
- Department of Microbiology, Key Lab of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, People's Republic of China
| | - Long Zhang
- Department of Microbiology, Key Lab of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, People's Republic of China
| | - Xiaowei Liu
- Department of Microbiology, Key Lab of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, People's Republic of China
| | - Shaochuang Chuang
- Department of Microbiology, Key Lab of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, People's Republic of China
| | - Shunpeng Li
- Department of Microbiology, Key Lab of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, People's Republic of China
| | - Jiandong Jiang
- Department of Microbiology, Key Lab of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, People's Republic of China.
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Liu J, Lopez N, Ahn Y, Goldberg T, Bromberg Y, Kerkhof LJ, Häggblom MM. Novel reductive dehalogenases from the marine sponge associated bacterium Desulfoluna spongiiphila. ENVIRONMENTAL MICROBIOLOGY REPORTS 2017; 9:537-549. [PMID: 28618195 DOI: 10.1111/1758-2229.12556] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Revised: 05/08/2017] [Accepted: 06/03/2017] [Indexed: 06/07/2023]
Abstract
Desulfoluna spongiiphila strain AA1 is an organohalide respiring bacterium, isolated from the marine sponge Aplysina aerophoba, that can use brominated and iodinated phenols, in addition to sulfate and thiosulfate as terminal electron acceptors. The genome of Desulfoluna spongiiphila strain AA1 is approximately 6.5 Mb. Three putative reductive dehalogenase (rdhA) genes involved in respiratory metabolism of organohalides were identified within the sequence. Conserved motifs found in respiratory reductive dehalogenases (a twin arginine translocation signal sequence and two iron-sulfur clusters) were present in all three putative AA1 rdhA genes. Transcription of one of the three rdhA genes was significantly upregulated during respiration of 2,6-dibromophenol and sponge extracts. Strain AA1 appears to have the ability to synthesize cobalamin, the key cofactor of most characterized reductive dehalogenase enzymes. The genome contains genes involved in cobalamin synthesis and uptake and can grow without cobalamin supplementation. Identification of this target gene associated with debromination lays the foundation for understanding how dehalogenating bacteria control the fate of organohalide compounds in sponges and their role in a symbiotic organobromine cycle. In the sponge environment, D. spongiiphila strain AA1 may thus take advantage of both brominated compounds and sulfate as electron acceptors for respiration.
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Affiliation(s)
- Jie Liu
- Departments of Biochemistry and Microbiology, School of Environmental and Biological Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA
| | - Nora Lopez
- Departments of Biochemistry and Microbiology, School of Environmental and Biological Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA
- Marine and Coastal Sciences, School of Environmental and Biological Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA
| | - Youngbeom Ahn
- Departments of Biochemistry and Microbiology, School of Environmental and Biological Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA
| | - Tatyana Goldberg
- Department for Bioinformatics and Computational Biology, Technical University Munich, Garching, 85748, Germany
| | - Yana Bromberg
- Departments of Biochemistry and Microbiology, School of Environmental and Biological Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA
| | - Lee J Kerkhof
- Marine and Coastal Sciences, School of Environmental and Biological Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA
| | - Max M Häggblom
- Departments of Biochemistry and Microbiology, School of Environmental and Biological Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA
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Pshenichnyuk SA, Modelli A, Lazneva EF, Komolov AS. Role of Resonance Electron Attachment in Phytoremediation of Halogenated Herbicides. J Phys Chem B 2016; 120:12098-12104. [DOI: 10.1021/acs.jpcb.6b10149] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Stanislav A. Pshenichnyuk
- Institute
of Molecule and Crystal Physics, Ufa Research Centre, Russian Academy of Sciences, Prospeκt Oktyabrya 151, 450075 Ufa, Russia
- St. Petersburg State University, Universitetskaya nab. 7/9, 199034 St. Petersburg, Russia
| | - Alberto Modelli
- Dipartimento
di Chimica “G. Ciamician”, Università di Bologna, via Selmi 2, 40126 Bologna, Italy
- Centro Interdipartimentale di Ricerca in Scienze Ambientali, via S. Alberto 163, 48123 Ravenna, Italy
| | - Eleonora F. Lazneva
- St. Petersburg State University, Universitetskaya nab. 7/9, 199034 St. Petersburg, Russia
| | - Alexei S. Komolov
- St. Petersburg State University, Universitetskaya nab. 7/9, 199034 St. Petersburg, Russia
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Kuppusamy S, Palanisami T, Megharaj M, Venkateswarlu K, Naidu R. Ex-Situ Remediation Technologies for Environmental Pollutants: A Critical Perspective. REVIEWS OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2016; 236:117-192. [PMID: 26423074 DOI: 10.1007/978-3-319-20013-2_2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Pollution and the global health impacts from toxic environmental pollutants are presently of great concern. At present, more than 100 million people are at risk from exposure to a plethora of toxic organic and inorganic pollutants. This review is an exploration of the ex-situ technologies for cleaning-up the contaminated soil, groundwater and air emissions, highlighting their principles, advantages, deficiencies and the knowledge gaps. Challenges and strategies for removing different types of contaminants, mainly heavy metals and priority organic pollutants, are also described.
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Affiliation(s)
- Saranya Kuppusamy
- CERAR-Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, SA, 5095, Australia
- CRC CARE-Cooperative Research Centre for Contamination Assessment and Remediation of Environment, 486, Salisbury South, SA, 5106, Australia
| | - Thavamani Palanisami
- CRC CARE-Cooperative Research Centre for Contamination Assessment and Remediation of Environment, 486, Salisbury South, SA, 5106, Australia
- GIER- Global Institute for Environmental Research, Faculty of Science and Information Technology, The University of Newcastle, Callaghan, NSW, 2308, Australia
| | - Mallavarapu Megharaj
- CRC CARE-Cooperative Research Centre for Contamination Assessment and Remediation of Environment, 486, Salisbury South, SA, 5106, Australia.
- GIER- Global Institute for Environmental Research, Faculty of Science and Information Technology, The University of Newcastle, Callaghan, NSW, 2308, Australia.
| | - Kadiyala Venkateswarlu
- Formerly Department of Microbiology, Sri Krishnadevaraya University, Anantapur, 515055, India
| | - Ravi Naidu
- CRC CARE-Cooperative Research Centre for Contamination Assessment and Remediation of Environment, 486, Salisbury South, SA, 5106, Australia
- GIER- Global Institute for Environmental Research, Faculty of Science and Information Technology, The University of Newcastle, Callaghan, NSW, 2308, Australia
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Faizi MSH, Mashrai A, Shahid M. 2,2,6,6-Tetra-bromo-3,4,4,5-tetra-meth-oxy-cyclo-hexa-none. Acta Crystallogr Sect E Struct Rep Online 2014; 70:o826. [PMID: 25161601 PMCID: PMC4120536 DOI: 10.1107/s160053681401472x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 06/22/2014] [Indexed: 11/15/2022]
Abstract
In the title compound, C10H14Br4O5, synthesized from the methoxy Schiff base N-(pyridin-2-ylmethyl)methoxyaniline and molecular bromine, the cyclohexanone ring has a chair conformation with one of the four methoxy groups equatorially orientated with respect to the carbonyl group and the others axially orientated. The C—Br bond lengthsvary from 1.942 (4) to1.964 (4) Å. In the crystal, weak C—H⋯Ocarbonyl hydrogen-bonding interactions generate chains extending along the b-axis direction. Also present in the structure are two short intermolecular Br⋯Omethoxy interactions [3.020 (3) and 3.073 (4) Å].
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Affiliation(s)
- Md Serajul Haque Faizi
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, UP 208 016, India
| | - Ashraf Mashrai
- Department of Chemistry, Aligarh Muslim University, Aligarh 202 002, India
| | - M Shahid
- Department of Chemistry, Aligarh Muslim University, Aligarh 202 002, India
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Oba Y, Futagami T, Amachi S. Enrichment of a microbial consortium capable of reductive deiodination of 2,4,6-triiodophenol. J Biosci Bioeng 2014; 117:310-7. [DOI: 10.1016/j.jbiosc.2013.08.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 08/13/2013] [Accepted: 08/20/2013] [Indexed: 12/01/2022]
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Chen K, Huang L, Xu C, Liu X, He J, Zinder SH, Li S, Jiang J. Molecular characterization of the enzymes involved in the degradation of a brominated aromatic herbicide. Mol Microbiol 2013; 89:1121-39. [PMID: 23859214 DOI: 10.1111/mmi.12332] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/13/2013] [Indexed: 11/26/2022]
Abstract
Dehalogenation is the key step in the degradation of halogenated aromatics, while reductive dehalogenation is originally thought to rarely occur in aerobes. In this study, an aerobic strain of Comamonas sp. 7D-2 was shown to degrade the brominated aromatic herbicide bromoxynil completely and release two equivalents of bromides under aerobic conditions. The enzymes involved in the degradation of bromoxynil to 4-carboxy-2-hydroxymuconate-6-semialdehyde, including nitrilase, reductive dehalogenase (BhbA), 4-hydroxybenzoate 3-monooxygenase and protocatechuate 4,5-dioxygenase, were molecularly characterized. The novel dehalogenase BhbA was shown to be a complex of a respiration-linked reductive dehalogenase (RdhA) domain and a NAD(P)H-dependent oxidoreductase domain and to have key features of anaerobic respiratory RdhAs, including two predicted binding motifs for [4Fe-4S] clusters and a close association with a hydrophobic membrane protein (BhbB). BhbB was confirmed to anchor BhbA to the membrane. BhbA was partially purified and found to use NAD(P)H as electron donors. Full-length bhbA homologues were found almost exclusively in marine aerobic proteobacteria, suggesting that reductive dehalogenation occurs extensively in aerobes and that bhbA is horizontally transferred from marine microorganisms. The discovery of a functional reductive dehalogenase and ring-cleavage oxygenases in an aerobe opens up possibilities for basic research as well as the potential application for bioremediation.
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Affiliation(s)
- Kai Chen
- Department of Microbiology, Key Lab of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, 210095, Nanjing, China
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18
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Affiliation(s)
- Christopher J Rhodes
- Fresh-lands Environmental Actions, 88 Star Road, Caversham, Berkshire RG4 5BE, UK.
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19
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Autodisplay of nitrilase from Klebsiella pneumoniae and whole-cell degradation of oxynil herbicides and related compounds. Appl Microbiol Biotechnol 2012; 97:4887-96. [DOI: 10.1007/s00253-012-4401-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Accepted: 08/30/2012] [Indexed: 10/27/2022]
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Wagner A, Cooper M, Ferdi S, Seifert J, Adrian L. Growth of Dehalococcoides mccartyi strain CBDB1 by reductive dehalogenation of brominated benzenes to benzene. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:8960-8968. [PMID: 22800291 DOI: 10.1021/es3003519] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Brominated aromatics are used in many different applications but occur also naturally. Here, we demonstrate organohalide respiration and growth of Dehalococcoides mccartyi strain CBDB1 with 1,2,4-tribromobenzene, all three dibrominated benzene congeners and monobromobenzene. All bromobenzenes were fully dehalogenated to benzene. Growth yields were between 1.8 × 10(14) and 2.8 × 10(14) cells per mol of bromide released. Furthermore, a newly designed high-throughput methyl viologen-based photometric microtiter plate assay was established to determine the activity of the reductive dehalogenases in resting cell assays of strain CBDB1 with brominated aromatics as electron acceptors. Activities of 2.8-13.2 nkat per mg total cell protein (0.16-0.8 units per mg total cell protein) were calculated after cultivation of strain CBDB1 on 1,2,4-tribromobenzene. Mass spectrometric analyses and activity assays with whole cell extracts of strain CBDB1 gave strong evidence that four to six reductive dehalogenases were involved in the dehalogenation of all tested brominated benzenes, including the reductive dehalogenases CbdbA80 and CbrA.
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Affiliation(s)
- Anke Wagner
- Applied Biochemistry, Technische Universität Berlin, Gustav-Meyer-Allee 25, 13355 Berlin, Germany
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Chen XX, Li WM, Wu Q, Zhi YN, Han LJ. Bromoxynil residues and dissipation rates in maize crops and soil. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2011; 74:1659-1663. [PMID: 21680020 DOI: 10.1016/j.ecoenv.2011.05.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Revised: 05/18/2011] [Accepted: 05/22/2011] [Indexed: 05/30/2023]
Abstract
A residue analytical method for the determination of bromoxynil in soil and maize was developed using high performance liquid chromatography with diode-array detector (HPLC-DAD) and high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). The residual level and dissipation rate of bromoxynil in the soil and maize crops were determined using the established method. The mean half-life of bromoxynil in soil was 4.12 days with a dissipation rate of 91.25% over 21 days. The mean half-life in maize seedling was 1.14 days with a dissipation rate of 97.79% over 7 days. The final residues of bromoxynil were undetectable in maize grain, maize stem and soil at the harvest time, suggesting that residual levels of bromoxynil in maize plants are safe to humans and animals as well as to the environment.
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Affiliation(s)
- Xiao-Xu Chen
- China Agricultural University, College of Science, Beijing 100193, China.
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Sokolová R, Hromadová M, Ludvík J, Pospíšil L, Giannarelli S. The autoprotonation in reduction mechanism of pesticide ioxynil. Electrochim Acta 2010. [DOI: 10.1016/j.electacta.2010.01.094] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Zablotowicz RM, Krutz LJ, Accinelli C, Reddy KN. Bromoxynil degradation in a Mississippi silt loam soil. PEST MANAGEMENT SCIENCE 2009; 65:658-664. [PMID: 19288470 DOI: 10.1002/ps.1730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
BACKGROUND The objectives of these laboratory experiments were: (1) to assess bromoxynil sorption, mineralization, bound residue formation and extractable residue persistence in a Dundee silt loam collected from 0-2 cm and 2-10 cm depths under continuous conventional tillage and no-tillage; (2) to assess the effects of autoclaving on bromoxynil mineralization and bound residue formation; (3) to determine the partitioning of non-extractable residues; and (4) to ascertain the effects of bromoxynil concentration on extractable and bound residues and metabolite formation. RESULTS Bromoxynil K(d) values ranged from 0.7 to 1.4 L kg(-1) and were positively correlated with soil organic carbon. Cumulative mineralization (38.5% +/- 1.5), bound residue formation (46.5% +/- 0.5) and persistence of extractable residues (T(1/2) < 1 day) in non-autoclaved soils were independent of tillage and depth. Autoclaving decreased mineralization and bound residue formation 257-fold and 6.0-fold respectively. Bromoxynil persistence in soil was rate independent (T(1/2) < 1 day), and the majority of non-extractable residues (87%) were associated with the humic acid fraction of soil organic matter. CONCLUSIONS Irrespective of tillage or depth, bromoxynil half-life in native soil is less than 1 day owing to rapid incorporation of the herbicide into non-extractable residues. Bound residue formation is governed principally by biochemical metabolite formation and primarily associated with soil humic acids that are moderately bioavailable for mineralization. These data indicate that the risk of off-site transport of bromoxynil residues is low owing to rapid incorporation into non-extractable residues.
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Affiliation(s)
- Robert M Zablotowicz
- USDA-Agricultural Research Service, Southern Weed Science Research Unit, Stoneville, MS 38776, USA.
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Holtze MS, Sørensen SR, Sørensen J, Aamand J. Microbial degradation of the benzonitrile herbicides dichlobenil, bromoxynil and ioxynil in soil and subsurface environments--insights into degradation pathways, persistent metabolites and involved degrader organisms. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2008; 154:155-168. [PMID: 17988770 DOI: 10.1016/j.envpol.2007.09.020] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2007] [Revised: 09/05/2007] [Accepted: 09/20/2007] [Indexed: 05/25/2023]
Abstract
The benzonitriles dichlobenil, bromoxynil and ioxynil are important broad-spectrum or selective herbicides used in agriculture, orchards and public areas worldwide. The dichlobenil metabolite 2,6-dichlorobenzamide is the most frequently encountered groundwater contaminant in Denmark, which suggests that the environmental fate of these three structurally related benzonitrile herbicides should be addressed in detail. This review summarises the current knowledge on microbial degradation of dichlobenil, bromoxynil and ioxynil with particular focus on common features of degradation rates and pathways, accumulation of persistent metabolites and diversity of the involved degrader organisms.
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Affiliation(s)
- Maria S Holtze
- Department of Geochemistry, Geological Survey of Denmark and Greenland (GEUS), Øster Voldgade 10, 1350 Copenhagen K, Denmark
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Kim YM, Nam IH, Murugesan K, Schmidt S, Crowley DE, Chang YS. Biodegradation of diphenyl ether and transformation of selected brominated congeners by Sphingomonas sp. PH-07. Appl Microbiol Biotechnol 2007; 77:187-94. [PMID: 17694301 DOI: 10.1007/s00253-007-1129-z] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2007] [Revised: 07/13/2007] [Accepted: 07/14/2007] [Indexed: 10/23/2022]
Abstract
Polybrominated diphenyl ethers (PBDEs) are common flame-retardant chemicals that are used in diverse commercial products such as textiles, circuit boards, and plastics. Because of the widespread production and improper disposal of materials that contain PBDEs, there has been an increasing accumulation of these compounds in the environment. The toxicity and bioavailability of PBDEs are variable for different congeners, with some congeners showing dioxin-like activities and estrogenicity. The diphenyl ether-utilizing bacterium Sphingomonas sp. PH-07 was enriched from activated sludge of a wastewater treatment plant. In liquid cultures, this strain mineralized 1 g of diphenyl ether per liter completely within 6 days. The metabolites detected and identified by gas chromatography/mass spectrometry (MS) and electrospray ionization/MS analysis corresponded with a feasible degradative pathway. However, the strain PH-07 even catabolized several brominated congeners such as mono-, di-, and tribrominated diphenyl ethers thereby producing the corresponding metabolites.
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Affiliation(s)
- Young-Mo Kim
- School of Environmental Science and Engineering, Pohang University of Science and Technology, Pohang, South Korea
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Hong M, Ping Z, Jian X. Testicular toxicity and mechanisms of chlorotoluron compounds in the mouse. Toxicol Mech Methods 2007; 17:483-8. [PMID: 20020875 DOI: 10.1080/15376510601166384] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
ABSTRACT Previous studies have reported that chlorotoluron has adverse effects on male mice. Few studies, however, have investigated the mechanism of the action of these herbicides. The study of the effects of chlorotoluron and atrazine ingestion on male mice reproductive function during a critical developmental period, the peripubertal period, is reported here. Chlorotoluron and/or atrazine were administered by PO gavage to mice from day 27 to day 52. The decreased weight ratio of mouse testis to body weight resulted in a reduction in the relative testis weight. Histological study of testis showed that the seminiferous epithelium arrayed loosely and disorderedly, spermatogenic cells became shed, and fewer layers were formed. With the use of an electron microscope, it was noted that mitochondria in the seminiferous epithelium appeared vacuolated; karyotheca swelled and bent. In addition, the number of Sertoli cells was reduced, and part of the tight junction was destroyed. The results of the present study demonstrated that herbicides in all administrated doses caused detrimental changes in mice. The toxic effects of chlorotoluron were more potent than those of atrazine when administrated alone. Moreover, the two compounds have synergistic toxic effects with combination use. All dose paradigms induced degeneration and severe pathological changes in a manner of dose response.
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Affiliation(s)
- Mu Hong
- Medical College of Nankai University, Tianjin, China, 300071
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Abstract
Desulfitobacterium spp. are strictly anaerobic bacteria that were first isolated from environments contaminated by halogenated organic compounds. They are very versatile microorganisms that can use a wide variety of electron acceptors, such as nitrate, sulfite, metals, humic acids, and man-made or naturally occurring halogenated organic compounds. Most of the Desulfitobacterium strains can dehalogenate halogenated organic compounds by mechanisms of reductive dehalogenation, although the substrate spectrum of halogenated organic compounds varies substantially from one strain to another, even with strains belonging to the same species. A number of reductive dehalogenases and their corresponding gene loci have been isolated from these strains. Some of these loci are flanked by transposition sequences, suggesting that they can be transmitted by horizontal transfer via a catabolic transposon. Desulfitobacterium spp. can use H2 as electron donor below the threshold concentration that would allow sulfate reduction and methanogenesis. Furthermore, there is some evidence that syntrophic relationships occur between Desulfitobacterium spp. and sulfate-reducing bacteria, from which the Desulfitobacterium cells acquire their electrons by interspecies hydrogen transfer, and it is believed that this relationship also occurs in a methanogenic consortium. Because of their versatility, desulfitobacteria can be excellent candidates for the development of anaerobic bioremediation processes. The release of the complete genome of Desulfitobacterium hafniense strain Y51 and information from the partial genome sequence of D. hafniense strain DCB-2 will certainly help in predicting how desulfitobacteria interact with their environments and other microorganisms, and the mechanisms of actions related to reductive dehalogenation.
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Gauthier A, Beaudet R, Lépine F, Juteau P, Villemur R. Occurrence and expression ofcrdAandcprA5encoding chloroaromatic reductive dehalogenases inDesulfitobacteriumstrains. Can J Microbiol 2006; 52:47-55. [PMID: 16541158 DOI: 10.1139/w05-111] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Desulfitobacterium hafniense PCP-1 (formerly frappieri PCP-1) has two reductive dehalogenases (RDases) that have been characterized. One is a membrane-associated 2,4,6-trichlorophenol RDase, which is encoded by crdA, and the other is a 3,5-dichlorophenol RDase encoded by cprA5. In this report, we determined the occurrence of these two RDase genes in seven other Desulfitobacterium strains. The presence or absence of these two RDases may explain the differences in the spectrum of halogenated compounds by these Desulfitobacterium strains. crdA gene sequences were found in all of the tested strains. It was expressed in strain PCP-1 regardless of the absence or presence of chlorophenols in the culture medium. crdA was also expressed in D. hafniense strains DCB-2 and TCE-1. cprA5 was detected only in D. hafniense strains PCP-1, TCP-A, and DCB-2. In these strains, cprA5 transcripts were detected only in the presence of chlorophenols. We also examined the expression of putative cprA RDases (cprA2, cprA3, and cprA4) that were shown to exist in the D. hafniense DCB-2 genome. RT-PCR experiments showed that cprA2, cprA3, and cprA4 were expressed in D. hafniense strains PCP-1, DCB-2, and TCP-A in the presence of chlorophenols. However, contrary to cprA5, these three genes were also expressed in the absence of halogenated compounds in the culture medium.Key words: reductive dehalogenase, Desulfitobacterium, gene family, gene expression.
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