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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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Egelkamp R, Friedrich I, Hertel R, Daniel R. From sequence to function: a new workflow for nitrilase identification. Appl Microbiol Biotechnol 2020; 104:4957-4970. [PMID: 32291488 PMCID: PMC7228900 DOI: 10.1007/s00253-020-10544-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Revised: 02/28/2020] [Accepted: 03/11/2020] [Indexed: 11/16/2022]
Abstract
Abstract Nitrilases are industrially important biocatalysts due to their ability to degrade nitriles to carboxylic acids and ammonia. In this study, a workflow for simple and fast recovery of nitrilase candidates from metagenomes is presented. For identification of active enzymes, a NADH-coupled high-throughput assay was established. Purification of enzymes could be omitted as the assay is based on crude extract containing the expressed putative nitrilases. In addition, long incubation times were avoided by combining nitrile and NADH conversion in a single reaction. This allowed the direct measurement of nitrile degradation and provided not only insights into substrate spectrum and specificity but also in degradation efficiency. The novel assay was used for investigation of candidate nitrilase-encoding genes. Seventy putative nitrilase-encoding gene and the corresponding deduced protein sequences identified during sequence-based screens of metagenomes derived from nitrile-treated microbial communities were analyzed. Subsequently, the assay was applied to 13 selected candidate genes and proteins. Six of the generated corresponding Escherichia coli clones produced nitrilases that showed activity and one unusual nitrilase was purified and analyzed. The activity of the novel arylacetonitrilase Nit09 exhibited a broad pH range and a high long-term stability. The enzyme showed high activity for arylacetonitriles with a KM of 1.29 mM and a Vmax of 13.85 U/mg protein for phenylacetonitrile. In conclusion, we provided a setup for simple and rapid analysis of putative nitrilase-encoding genes from sequence to function. The suitability was demonstrated by identification, isolation, and characterization of the arylacetonitrilase. Key points • A simple and fast high-throughput nitrilase screening was developed. • A set of putative nitrilases was successfully screened with the assay. • A novel arylacetonitrilase was identified, purified, and characterized in detail. Electronic supplementary material The online version of this article (10.1007/s00253-020-10544-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Richard Egelkamp
- Genomic and Applied Microbiology & Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University of Göttingen, Grisebachstraße 8, 37077, Göttingen, Germany
| | - Ines Friedrich
- Genomic and Applied Microbiology & Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University of Göttingen, Grisebachstraße 8, 37077, Göttingen, Germany
| | - Robert Hertel
- Genomic and Applied Microbiology & Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University of Göttingen, Grisebachstraße 8, 37077, Göttingen, Germany
| | - Rolf Daniel
- Genomic and Applied Microbiology & Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University of Göttingen, Grisebachstraße 8, 37077, Göttingen, Germany.
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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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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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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: 73] [Impact Index Per Article: 10.4] [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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Efficient biodegradation of dihalogenated benzonitrile herbicides by recombinant Escherichia coli harboring nitrile hydratase-amidase pathway. Biochem Eng J 2017. [DOI: 10.1016/j.bej.2017.05.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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7
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Pasquarelli F, Spera A, Cantarella L, Cantarella M. Biodegradation of bromoxynil using the cascade enzymatic system nitrile hydratase/amidase from Microbacterium imperiale CBS 498-74. Comparison between free enzymes and resting cells. RSC Adv 2015. [DOI: 10.1039/c5ra01438g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
This work investigates the biodegradation of bromoxynil to the corresponding acid to reduce its acute toxicity.
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Affiliation(s)
- Fabrizia Pasquarelli
- Department of Industrial and Information Engineering and Economics
- University of L'Aquila
- 67100 L'Aquila
- Italy
| | - Agata Spera
- Department of Industrial and Information Engineering and Economics
- University of L'Aquila
- 67100 L'Aquila
- Italy
| | - Laura Cantarella
- Department of Civil and Mechanical Engineering
- University of Cassino and Southern Lazio
- 03043 Cassino
- Italy
| | - Maria Cantarella
- Department of Industrial and Information Engineering and Economics
- University of L'Aquila
- 67100 L'Aquila
- Italy
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Frková Z, Badawi N, Johansen A, Schultz-Jensen N, Bester K, Sørensen SR, Karlson UG. Degradation of three benzonitrile herbicides by Aminobacter MSH1 versus soil microbial communities: pathways and kinetics. PEST MANAGEMENT SCIENCE 2014; 70:1291-1298. [PMID: 24302680 DOI: 10.1002/ps.3697] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 11/21/2013] [Accepted: 12/02/2013] [Indexed: 06/02/2023]
Abstract
BACKGROUND The herbicide dichlobenil was banned in the European Union after its metabolite 2,6-dichlorobenzamide (BAM) was encountered in groundwater. Owing to structural similarities, bromoxynil and ioxynil might be converted to persistent metabolites in a similar manner. To examine this, we used an indigenous soil bacterium Aminobacter sp. MSH1 which is capable of mineralizing dichlobenil via BAM and 2,6-dichlorobenzoic acid (2,6-DCBA). RESULTS Strain MSH1 converted bromoxynil and ioxynil to the corresponding aromatic metabolites, 3,5-dibromo-4-hydroxybenzoic acid (BrAC) and 3,5-diiodo-4-hydroxybenzoic acid (IAC) following Michaelis-Menten kinetics (adjusted R(2) between 0.907 and 0.999). However, in contrast to 2,6-DCBA, degradation of these metabolites was not detected in the pure-culture studies, suggesting that they might pose an environmental risk if similar partial degradation occurred in soil. By contrast, experiments with natural soils indicated 20-30% mineralization of ioxynil and bromoxynil within the first week. CONCLUSION The degradation pathway of the three benzonitriles is initially driven by similar enzymes, after which more specific enzymes are responsible for further degradation. Ioxynil and bromoxynil mineralization in soil is not dependent on previous benzonitrile exposure. The accumulation of dead-end metabolites, as seen for dichlobenil, is not a major problem.
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Affiliation(s)
- Zuzana Frková
- Department of Environmental Science, Aarhus University, Frederiksborgvej 399, 4000, Roskilde, Denmark
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Li R, Jin J. Model predictions of toxaphene degradation in the atmosphere over North America. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2013; 32:2663-2671. [PMID: 23939819 DOI: 10.1002/etc.2344] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 02/08/2013] [Accepted: 08/02/2013] [Indexed: 06/02/2023]
Abstract
Technical toxaphene, a broad-spectrum pesticide mixture, degrades in the environment, resulting in potential changes in toxicity. The present study uses a multimedia model that the authors developed to estimate toxaphene degradation in the atmosphere over North America. The predicted degradation has strong spatial and temporal variability determined by processes such as emission and transport of technical toxaphene, as well as the complex interactions among many species (e.g., toxaphene, hydroxyl [OH] radicals, and ozone). More toxaphene is degraded in warmer months due to higher concentrations of technical toxaphene (primarily due to higher technical toxaphene emissions in the southeastern United States and transport to other regions) and OH radicals. In the model, OH radicals are created primarily through the reactions of water vapor with the excited oxygen atom, O(¹D), generated by the photolysis of ozone, which is produced primarily by reactions of volatile organic compounds and nitrogen oxides (NOx) in the presence of sunlight. The higher OH concentrations in warmer months are primarily the result of higher solar radiation and ozone concentrations. The spatial distribution of degradation depends on the distribution of technical toxaphene soil residues as well as atmospheric transport and chemistry; significant chemical degradation occurs in the southeastern United States where soils are most heavily contaminated by past applications of toxaphene.
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Affiliation(s)
- R Li
- Department of Plants, Soils, and Climate, Utah State University, Logan, Utah, USA
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10
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Acrylamide biodegradation ability and plant growth-promoting properties of Variovorax boronicumulans CGMCC 4969. Biodegradation 2013; 24:855-64. [DOI: 10.1007/s10532-013-9633-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 03/09/2013] [Indexed: 10/27/2022]
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Veselá AB, Pelantová H, Sulc M, Macková M, Lovecká P, Thimová M, Pasquarelli F, Pičmanová M, Pátek M, Bhalla TC, Martínková L. Biotransformation of benzonitrile herbicides via the nitrile hydratase-amidase pathway in rhodococci. J Ind Microbiol Biotechnol 2012; 39:1811-9. [PMID: 22922990 DOI: 10.1007/s10295-012-1184-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Accepted: 07/31/2012] [Indexed: 10/28/2022]
Abstract
The aim of this work was to determine the ability of rhodococci to transform 3,5-dichloro-4-hydroxybenzonitrile (chloroxynil), 3,5-dibromo-4-hydroxybenzonitrile (bromoxynil), 3,5-diiodo-4-hydroxybenzonitrile (ioxynil) and 2,6-dichlorobenzonitrile (dichlobenil); to identify the products and determine their acute toxicities. Rhodococcus erythropolis A4 and Rhodococcus rhodochrous PA-34 converted benzonitrile herbicides into amides, but only the former strain was able to hydrolyze 2,6-dichlorobenzamide into 2,6-dichlorobenzoic acid, and produced also more of the carboxylic acids from the other herbicides compared to strain PA-34. Transformation of nitriles into amides decreased acute toxicities for chloroxynil and dichlobenil, but increased them for bromoxynil and ioxynil. The amides inhibited root growth in Lactuca sativa less than the nitriles but more than the acids. The conversion of the nitrile group may be the first step in the mineralization of benzonitrile herbicides but cannot be itself considered to be a detoxification.
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Affiliation(s)
- Alicja B Veselá
- Institute of Microbiology of the Academy of Sciences of the Czech Republic, Vídeňská 1083, 14220 Prague, Czech Republic
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Sokolová R, Gál M, Valášek M. New proton donors in electrochemical mechanistic studies in non-aqueous solution dimethylsulfoxide: Chlorinated hydroxybenzonitriles. J Electroanal Chem (Lausanne) 2012. [DOI: 10.1016/j.jelechem.2012.09.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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13
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Zhang HJ, Zhou QW, Zhou GC, Cao YM, Dai YJ, Ji WW, Shang GD, Yuan S. Biotransformation of the neonicotinoid insecticide thiacloprid by the bacterium Variovorax boronicumulans strain J1 and mediation of the major metabolic pathway by nitrile hydratase. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2012; 60:153-159. [PMID: 22148554 DOI: 10.1021/jf203232u] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A neonicotinoid insecticide thiacloprid-degrading bacterium strain J1 was isolated from soil and identified as Variovorax boronicumulans by 16S rRNA gene sequence analysis. Liquid chromatography-mass spectrometry and nuclear magnetic resonance analysis indicated the major pathway of thiacloprid (THI) metabolism by V. boronicumulans J1 involved hydrolysis of the N-cyanoimino group to form an N-carbamoylinino group containing metabolite, THI amide. Resting cells of V. boronicumulans J1 degraded 62.5% of the thiacloprid at a concentration of 200 mg/L in 60 h, and 98% of the reduced thiacloprid was converted to the final metabolite thiacloprid amide. A 2.6 kb gene cluster from V. boronicumulans J1 that includes the full length of the nitrile hydratase gene was cloned and investigated by degenerate primer polymerase chain reaction (PCR) and inverse PCR. The nitrile hydratase gene has a length of 1304 bp and codes a cobalt-type nitrile hydratase with an α-subunit of 213 amino acids and a β-subunit of 221 amino acids. The nitrile hydratase gene was recombined into plasmid pET28a and overexpressed in Escherichia coli BL21 (DE3). The resting cells of recombinant E. coli BL21 (DE3)-pET28a-NHase with overexpression of nitrile hydratase transformed thiacloprid to its amide metabolite, whereas resting cells of the control E. coli BL21 (DE3)-pET28a did not. Therefore, the major hydration pathway of thiacloprid is mediated by nitrile hydratase.
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Affiliation(s)
- Hui-Juan Zhang
- Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Science, Nanjing Normal University, Nanjing 210046, People's Republic of China
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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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15
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Veselá AB, Franc M, Pelantová H, Kubác D, Vejvoda V, Sulc M, Bhalla TC, Macková M, Lovecká P, Janů P, Demnerová K, Martínková L. Hydrolysis of benzonitrile herbicides by soil actinobacteria and metabolite toxicity. Biodegradation 2010; 21:761-70. [PMID: 20204468 DOI: 10.1007/s10532-010-9341-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2009] [Accepted: 02/08/2010] [Indexed: 11/25/2022]
Abstract
The soil actinobacteria Rhodococcus rhodochrous PA-34, Rhodococcus sp. NDB 1165 and Nocardia globerula NHB-2 grown in the presence of isobutyronitrile exhibited nitrilase activities towards benzonitrile (approx. 1.1-1.9 U mg(-1) dry cell weight). The resting cell suspensions eliminated benzonitrile and the benzonitrile analogues chloroxynil (3,5-dichloro-4-hydroxybenzonitrile), bromoxynil (3,5-dibromo-4-hydroxybenzonitrile) and ioxynil (3,5-diiodo-4-hydroxybenzonitrile) (0.5 mM each) from reaction mixtures at 30 degrees C and pH 8.0. The products were isolated and identified as the corresponding substituted benzoic acids. The reaction rates decreased in the order benzonitrile >> chloroxynil > bromoxynil > ioxynil in all strains. Depending on the strain, 92-100, 70-90 and 30-51% of chloroxynil, bromoxynil and ioxynil, respectively, was hydrolyzed after 5 h. After a 20-h incubation, almost full conversion of chloroxynil and bromoxynil was observed in all strains, while only about 60% of the added ioxynil was converted into carboxylic acid. The product of ioxynil was not metabolized any further, and those of the other two herbicides very slowly. None of the nitrilase-producing strains hydrolyzed dichlobenil (2,6-dichlorobenzonitrile). 3,5-Dibromo-4-hydroxybenzoic acid exhibited less inhibitory effect than bromoxynil both on luminescent bacteria and germinating seeds of Lactuca sativa. 3,5-Diiodo-4-hydroxybenzoic acid only exhibited lower toxicity than ioxynil in the latter test.
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Affiliation(s)
- A B Veselá
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Vídenská , Praha, Czech Republic
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16
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Dai YJ, Ji WW, Chen T, Zhang WJ, Liu ZH, Ge F, Yuan S. Metabolism of the Neonicotinoid insecticides acetamiprid and thiacloprid by the yeast Rhodotorula mucilaginosa strain IM-2. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:2419-25. [PMID: 20112912 DOI: 10.1021/jf903787s] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
A yeast identified as Rhodotorula mucilaginosa strain IM-2 was able to degrade acetamiprid (AAP) and thiacloprid (THI) in sucrose mineral salt medium with half-lives of 3.7 and 14.8 days, respectively, while it did not degrade imidacloprid and imidaclothiz. Identification of metabolites indicated that R. mucilaginosa IM-2 selectively converted AAP and THI by hydrolysis of AAP to form an intermediate metabolite IM 1-3 and hydrolysis of THI to form an amide derivative, respectively. Metabolite IM 1-3 had no insecticidal activity, while the THI amide showed considerable insecticidal activity but was 15.6 and 38.6 times lower than the parent THI following oral ingestion and a contact test against the horsebean aphid Aphis craccivora , respectively. The inoculated R. mucilaginosa IM-2 displayed biodegradability of AAP and THI in clay soils.
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Affiliation(s)
- Yi-Jun Dai
- Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Science, Nanjing Normal University, Nanjing 210046, People's Republic of China
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Martínez Vidal J, Plaza-Bolaños P, Romero-González R, Garrido Frenich A. Determination of pesticide transformation products: A review of extraction and detection methods. J Chromatogr A 2009; 1216:6767-88. [DOI: 10.1016/j.chroma.2009.08.013] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2009] [Revised: 07/30/2009] [Accepted: 08/07/2009] [Indexed: 11/27/2022]
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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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Martínková L, Uhnáková B, Pátek M, Nesvera J, Kren V. Biodegradation potential of the genus Rhodococcus. ENVIRONMENT INTERNATIONAL 2009; 35:162-77. [PMID: 18789530 DOI: 10.1016/j.envint.2008.07.018] [Citation(s) in RCA: 284] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2008] [Revised: 07/02/2008] [Accepted: 07/22/2008] [Indexed: 05/24/2023]
Abstract
A large number of aromatic compounds and organic nitriles, the two groups of compounds covered in this review, are intermediates, products, by-products or waste products of the chemical and pharmaceutical industries, agriculture and the processing of fossil fuels. The majority of these synthetic substances (xenobiotics) are toxic and their release and accumulation in the environment pose a serious threat to living organisms. Bioremediation using various bacterial strains of the genus Rhodococcus has proved to be a promising option for the clean-up of polluted sites. The large genomes of rhodococci, their redundant and versatile catabolic pathways, their ability to uptake and metabolize hydrophobic compounds, to form biofilms, to persist in adverse conditions and the availability of recently developed tools for genetic engineering in rhodococci make them suitable industrial microorganisms for biotransformations and the biodegradation of many organic compounds. The peripheral and central catabolic pathways in rhodococci are characterized for each type of aromatics (hydrocarbons, phenols, halogenated, nitroaromatic, and heterocyclic compounds) in this review. Pathways involved in the hydrolysis of nitrile pollutants (aliphatic nitriles, benzonitrile analogues) and the corresponding enzymes (nitrilase, nitrile hydratase) are described in detail. Examples of regulatory mechanisms for the expression of the catabolic genes are given. The strains that efficiently degrade the compounds in question are highlighted and examples of their use in biodegradation processes are presented.
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Affiliation(s)
- Ludmila Martínková
- Centre of Biocatalysis and Biotransformation, Institute of Microbiology, Academy of Sciences of the Czech Republic, Vídenská 1083, CZ-142 20 Prague 4, Czech Republic.
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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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Holtze MS, Hansen HCB, Juhler RK, Sørensen J, Aamand J. Microbial degradation pathways of the herbicide dichlobenil in soils with different history of dichlobenil-exposure. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2007; 148:343-51. [PMID: 17240021 DOI: 10.1016/j.envpol.2006.10.028] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2006] [Revised: 09/25/2006] [Accepted: 10/01/2006] [Indexed: 05/13/2023]
Abstract
This is the first detailed study of metabolite production during degradation of the herbicide 2,6-dichlorobenzonitrile (dichlobenil). Degradation of dichlobenil and three potential metabolites: 2,6-dichlorobenzamide (BAM), 2,6-dichlorobenzoic acid (2,6-DCBA) and ortho-chlorobenzamide (OBAM) was studied in soils either previously exposed or not exposed to dichlobenil using a newly developed HPLC method. Dichlobenil was degraded in all four soils; BAM and 2,6-DCBA were only degraded in soils previously exposed to dichlobenil (100% within 35-56 days and 85-100% in 56 days, respectively), and OBAM in all four soils (25-33% removal in 48 days). BAM produced from dichlobenil was either hydrolyzed to 2,6-DCBA or dechlorinated to OBAM, which was further hydrolyzed to ortho-chlorobenzoic acid. BAM was rapidly mineralized in previously exposed soils only. All potential metabolites and the finding that BAM was a dead-end metabolite of dichlobenil in soils not previously exposed to dichlobenil needs to be included in risk assessments of the use of dichlobenil.
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Affiliation(s)
- Maria S Holtze
- Department of Natural Sciences, Soil and Environmental Chemistry, Royal Veterinary and Agricultural University, Thorvaldsensvej 40, Frederiksberg C, Denmark.
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