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Chen WJ, Chen SF, Song H, Li Z, Luo X, Zhang X, Zhou X. Current insights into environmental acetochlor toxicity and remediation strategies. ENVIRONMENTAL GEOCHEMISTRY AND HEALTH 2024; 46:356. [PMID: 39083106 DOI: 10.1007/s10653-024-02136-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2024] [Accepted: 07/16/2024] [Indexed: 09/07/2024]
Abstract
Acetochlor is a selective pre-emergent herbicide that is widely used to control annual grass and broadleaf weeds. However, due to its stable chemical structure, only a small portion of acetochlor exerts herbicidal activity in agricultural applications, while most of the excess remains on the surfaces of plants or enters ecosystems, such as soil and water bodies, causing harm to the environment and human health. In recent years, researchers have become increasingly focused on the repair of acetochlor residues. Compared with traditional physical and chemical remediation methods, microorganisms are the most effective way to remediate chemical pesticide pollution, such as acetochlor, because of their rich species, wide distribution, and diverse metabolic pathways. To date, researchers have isolated and identified many high-efficiency acetochlor-degrading strains, such as Pseudomonas oleovorans, Klebsiella variicola, Bacillus subtilus, Rhodococcus, and Methylobacillus, among others. The microbial degradation pathways of acetochlor include dechlorination, hydroxylation, N-dealkylation, C-dealkylation, and dehydrogenation. In addition, the microbial enzymes, including hydrolase (ChlH), debutoxylase (Dbo), and monooxygenase (MeaXY), responsible for acetochlor biodegradation are also being investigated. In this paper, we review the migration law of acetochlor in the environment, its toxicity to nontarget organisms, and the main metabolic methods. Moreover, we summarize the latest progress in the research on the microbial catabolism of acetochlor, including the efficient degradation of microbial resources, biodegradation metabolic pathways, and key enzymes for acetochlor degradation. At the end of the article, we highlight the existing problems in the current research on acetochlor biodegradation, provide new ideas for the remediation of acetochlor pollution in the environment, and propose future research directions.
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Affiliation(s)
- Wen-Juan Chen
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, College of Plant Protection, South China Agricultural University, Guangzhou, 510642, China
| | - Shao-Fang Chen
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, College of Plant Protection, South China Agricultural University, Guangzhou, 510642, China
| | - Haoran Song
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, College of Plant Protection, South China Agricultural University, Guangzhou, 510642, China
| | - Zeren Li
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, College of Plant Protection, South China Agricultural University, Guangzhou, 510642, China
| | - Xiaofang Luo
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, College of Plant Protection, South China Agricultural University, Guangzhou, 510642, China
| | - Xidong Zhang
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, College of Plant Protection, South China Agricultural University, Guangzhou, 510642, China
| | - Xiaofan Zhou
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, College of Plant Protection, South China Agricultural University, Guangzhou, 510642, China.
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Liu J, Zhang X, Xu J, Qiu J, Zhu J, Cao H, He J. Anaerobic biodegradation of acetochlor by acclimated sludge and its anaerobic catabolic pathway. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 748:141122. [PMID: 32810802 DOI: 10.1016/j.scitotenv.2020.141122] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Revised: 07/10/2020] [Accepted: 07/18/2020] [Indexed: 06/11/2023]
Abstract
Acetochlor is a chloroacetamide herbicide that has been widely used for weed control in recent decades. The contamination from its residue in the environment has raised major serious concerns. The aerobic degradation of acetochlor has been well studied; however, little is known regarding its anaerobic degradation. In the study, anaerobic sludge with high acetochlor degradation efficiency was obtained by pressure acclimation in a continuous flow anaerobic reactor. The acetochlor degradation dynamics followed a first-order kinetic reaction equation. The acclimated sludge could degrade six chloroacetamide herbicides with the degradation efficiencies observed as alachlor > acetochlor > propisochlor > butachlor > pretilachlor > metolachlor, and the N-alkoxyalkyl structure of these herbicides significantly affected their biodegradability. Five metabolites, 2-ethyl-6-methyl-N-(ethoxymethyl)-acetanilide, N-(2-methyl-6-ethylphenyl) acetamide, N-2-ethylphenyl acetamide, N-2-ethylphenyl formamide and 2-ethyl-N-carboxyl aniline were identified, and a putative anaerobic acetochlor degradation pathway, initiated by dechlorination, was subsequently proposed. During acclimation, the community diversity of both eubacteria and archaea in the anaerobic sludge decreased, while the abundance of microbes belonging to genera Sporomusa, Sporobacterium, Dechloromonas, Azotobacter and Methanobacterium were significantly increased and dominated the acclimated sludge, and showing a positive correlation with the acetochlor degradation capacity. These findings should be valuable to elucidate the mechanisms associated with the anaerobic catabolism of acetochlor and facilitate the engineering application of anaerobic treatment for removing acetochlor from wastewater.
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Affiliation(s)
- Junwei Liu
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China.
| | - Xuan Zhang
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China.
| | - Jianyi Xu
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China.
| | - Jiguo Qiu
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China.
| | - Jianchun Zhu
- Laboratory Centre of Life Science, College of Life Science, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China.
| | - Hui Cao
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China.
| | - Jian He
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China.
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Duc HD, Oanh NT. Biodegradation of Acetochlor and 2-methyl-6-ethylaniline by Bacillus subtilis and Pseudomonasfluorescens. Microbiology (Reading) 2020. [DOI: 10.1134/s0026261719060031] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Kral AE, Pflug NC, McFadden ME, LeFevre GH, Sivey JD, Cwiertny DM. Photochemical Transformations of Dichloroacetamide Safeners. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:6738-6746. [PMID: 31117539 DOI: 10.1021/acs.est.9b00861] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Dichloroacetamide safeners are commonly added to commercial chloroacetamide herbicide formulations and widely used worldwide, but their environmental fate has garnered little scrutiny as a result of their classification as "inert" ingredients. Here, we investigated the photolysis of dichloroacetamide safeners to better understand their persistence and the nature of their transformation products in surface waters. High-resolution mass spectrometry (HRMS) and nuclear magnetic resonance (NMR) spectroscopy were used to characterize photoproducts. Of the four commonly used dichloroacetamide safeners, only benoxacor undergoes direct photolysis under simulated natural sunlight ( t1/2 ∼ 10 min). Via a photoinitiated ring closure, benoxacor initially yields a monochlorinated intermediate that degrades over longer irradiation time scales to produce two fully dechlorinated diastereomers and a tautomer, which further photodegrade over several days to a structurally related aldehyde confirmed via NMR. Dichlormid, AD-67, and furilazole were more slowly degraded by indirect photolysis in the presence of the photosensitizers nitrate, nitrite, and humic acid. Reactive entities involved in these reactions are likely hydroxyl radical and singlet oxygen based on the use of selective quenchers. These safeners also directly photolyzed under higher energy ultraviolet (UV) light, suggesting their potential transformation in engineered systems using UV for disinfection. The finding that dichloroacetamide safeners can undergo photolysis in environmental systems over relevant time scales demonstrates the importance of evaluating the fate of this class of "inert" agrochemicals.
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Affiliation(s)
- Andrew E Kral
- Department of Civil & Environmental Engineering , University of Iowa , 4105 Seamans Center for the Engineering Arts and Sciences, Iowa City , Iowa 52242 , United States
| | - Nicholas C Pflug
- Department of Chemistry , University of Iowa , E331 Chemistry Building, Iowa City , Iowa 52242 , United States
| | - Monica E McFadden
- Department of Civil & Environmental Engineering , University of Iowa , 4105 Seamans Center for the Engineering Arts and Sciences, Iowa City , Iowa 52242 , United States
| | - Gregory H LeFevre
- Department of Civil & Environmental Engineering , University of Iowa , 4105 Seamans Center for the Engineering Arts and Sciences, Iowa City , Iowa 52242 , United States
- IIHR-Hydroscience & Engineering University of Iowa , 100 C. Maxwell Stanley Hydraulics Laboratory, Iowa City , Iowa 52242 , United States
| | - John D Sivey
- Department of Chemistry , Towson University , 543 Smith Hall, Towson , Maryland 21252 , United States
| | - David M Cwiertny
- Department of Civil & Environmental Engineering , University of Iowa , 4105 Seamans Center for the Engineering Arts and Sciences, Iowa City , Iowa 52242 , United States
- Department of Chemical & Biochemical Engineering , University of Iowa , 4133 Seamans Center for the Engineering Arts and Sciences, Iowa City Iowa 52242 , United States
- IIHR-Hydroscience & Engineering University of Iowa , 100 C. Maxwell Stanley Hydraulics Laboratory, Iowa City , Iowa 52242 , United States
- Center for Health Effects of Environmental Contamination , University of Iowa , 251 North Capitol Street , Chemistry Building - Room W195, Iowa City , Iowa 52242 , United States
- Public Policy Center , University of Iowa , 310 South Grand Avenue , 209 South Quadrangle, Iowa City , Iowa 52242 , United States
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Murschell T, Farmer DK. Atmospheric OH oxidation chemistry of trifluralin and acetochlor. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2019; 21:650-658. [PMID: 30805573 DOI: 10.1039/c8em00507a] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Trifluralin and acetochlor are two nitrogen-containing current use herbicides. While both herbicides have been observed in the atmosphere and have the potential to undergo atmospheric oxidation before deposition to off-target areas, the atmospheric photooxidation chemistry of these species is poorly understood. We use an oxidative flow reactor to expose the two herbicides to increasing concentrations of OH radicals, detecting pesticides and products using an iodide chemical ionization mass spectrometer. We identify new oxidation products and propose photooxidation mechanisms for trifluralin and acetochlor. Both herbicides contain reduced organic nitrogen atoms, and their OH oxidation produces isocyanic acid. While aerosol was observed in the flow reactor only for acetochlor, our results indicate that OH oxidation of neither herbicide would contribute to secondary organic aerosol formation under typical ambient atmospheric conditions. However, high wall losses of both pesticides in the flow reactor suggests that partitioning to pre-existing aerosol may occur and enable subsequent transport in the atmosphere.
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Affiliation(s)
- Trey Murschell
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA.
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Assessment of genetic diversity and bioremediation potential of pseudomonads isolated from pesticide-contaminated artichoke farm soils. 3 Biotech 2018; 8:263. [PMID: 29805953 DOI: 10.1007/s13205-018-1256-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 04/23/2018] [Indexed: 01/18/2023] Open
Abstract
A total of 68 dimethoate and pentachlorophenol-tolerant rhizobacteria, isolated from a pesticide-contaminated agricultural soil, have been identified and typed by means of 16S-23S rRNA internal transcribed spacers analysis (ITS-PCR), 16S rRNA gene sequencing and by repetitive extragenic palindromic (BOX-PCR). The majority of bacterial isolates (84.31%) belonged to Proteobacteria (with a predominance of Gammaproteobacteria, 72.54%), while the remaining isolates were affiliated with Firmicutes (9.80%), Bacteroidetes (1.96%) and Actinobacteria (3.92%). The pesticide-tolerant bacterial isolates belonged to 11 genera, namely Pseudomonas, Bacillus, Acinetobacter, Flavobacterium, Comamonas, Achromobacter, Rhodococcus, Ochrobactrum, Aquamicrobium, Bordetella and Microbacterium. Within the well-represented genus Pseudomonas (n = 36), the most common species was Pseudomonas putida (n = 32). The efficacy of the selected strain, Pseudomonas putida S148, was further investigated for biodegradation of pentachlorophenol (PCP) in minimal medium, when used as a sole carbon and energy source. At an initial concentration of 100 mg/L, P. putida S148 degraded 91% of PCP after 7 days. GC-MS analyses revealed the formation of tetrachlorohydroquinone, tri- and di-chlorophenols as biodechlorination products in PCP remediation experiments. The toxicity estimation showed that 50% lethal concentration (LC50) and 50% growth inhibition concentration (IGC50) obtained values for the major identified compounds (2,3,4,6 tetrachlorophenol, 2,3,5,6 tetrachlorophenol and tetrachlorohydroquinone) were higher than those estimated for the PCP indicating that the metabolites are less toxic than the original compound for those specific organisms. S148 strain could be added to pesticide-contaminated agricultural soils as a bacterial inoculant for its potential to improve soil quality.
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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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Liquid chromatography coupled to tandem and high resolution mass spectrometry for the characterisation of ofloxacin transformation products after titanium dioxide photocatalysis. J Chromatogr A 2016; 1443:201-10. [DOI: 10.1016/j.chroma.2016.03.063] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 03/21/2016] [Accepted: 03/21/2016] [Indexed: 11/24/2022]
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Nicol É, Genty C, Bouchonnet S, Bourcier S. Structural elucidation of metolachlor photoproducts by liquid chromatography/high-resolution tandem mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2015; 29:2279-2286. [PMID: 26522321 DOI: 10.1002/rcm.7382] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 08/24/2015] [Accepted: 08/30/2015] [Indexed: 06/05/2023]
Abstract
RATIONALE Metolachlor is one of the most intensively used chloroacetanilide herbicides in agriculture. It has been detected in water; consequently, under UV-visible irradiation, it can be transformed in degradation products (TPs). The structures of TPs were elucidated by liquid chromatography/high-resolution tandem mass spectrometry (LC/HR-MS/MS). The potential toxicities of these TPs were estimated by in silico tests. METHODS Aqueous solutions of metolachlor were irradiated in a self-made reactor equipped with a mercury vapor lamp. Analyses were carried out using high-performance liquid chromatography coupled to quadrupole time-of-flight (QTOF) mass spectrometer. High-resolution m/z measurements, MS/MS and isotopic labeling experiments allowed structural elucidation of metolachlor TPs. Their toxicities were estimated in silico, using the T.E.S.T. RESULTS Ten major metolachlor photoproducts were characterized by LC/MS/MS after irradiation of metolachlor in aqueous solution. Elucidation of their chemical structures was identified using high-resolution measurements and MS/MS experiments. They resulted from the combination of dehalogenation, hydroxylation and cyclisation processes. The potential oral rat lethal dose (LD50) was assessed with QSAR tests for metolachlor and each photoproduct. Results indicate that most of the TPs are much more toxic than metolachlor. CONCLUSIONS UV-vis irradiation of metolachlor in aqueous solution leads to the formation of ten photoproducts. QSAR estimations show that the location of added hydroxyl group(s) is of key relevance as regards to biological activity and that routine water analysis should take into account the TPs are more toxic than the parent molecule.
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Affiliation(s)
- Édith Nicol
- École Polytechnique, Laboratoire de Chimie Moléculaire, UMR 9168 CNRS, route de Saclay, 91128, Palaiseau cedex, France
| | - Christophe Genty
- École Polytechnique, Laboratoire de Chimie Moléculaire, UMR 9168 CNRS, route de Saclay, 91128, Palaiseau cedex, France
| | - Stéphane Bouchonnet
- École Polytechnique, Laboratoire de Chimie Moléculaire, UMR 9168 CNRS, route de Saclay, 91128, Palaiseau cedex, France
| | - Sophie Bourcier
- École Polytechnique, Laboratoire de Chimie Moléculaire, UMR 9168 CNRS, route de Saclay, 91128, Palaiseau cedex, France
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Metabolic pathway involved in 2-methyl-6-ethylaniline degradation by Sphingobium sp. strain MEA3-1 and cloning of the novel flavin-dependent monooxygenase system meaBA. Appl Environ Microbiol 2015; 81:8254-64. [PMID: 26386060 DOI: 10.1128/aem.01883-15] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 09/11/2015] [Indexed: 11/20/2022] Open
Abstract
2-Methyl-6-ethylaniline (MEA) is the main microbial degradation intermediate of the chloroacetanilide herbicides acetochlor and metolachlor. Sphingobium sp. strain MEA3-1 can utilize MEA and various alkyl-substituted aniline and phenol compounds as sole carbon and energy sources for growth. We isolated the mutant strain MEA3-1Mut, which converts MEA only to 2-methyl-6-ethyl-hydroquinone (MEHQ) and 2-methyl-6-ethyl-benzoquinone (MEBQ). MEA may be oxidized by the P450 monooxygenase system to 4-hydroxy-2-methyl-6-ethylaniline (4-OH-MEA), which can be hydrolytically spontaneously deaminated to MEBQ or MEHQ. The MEA microbial metabolic pathway was reconstituted based on the substrate spectra and identification of the intermediate metabolites in both the wild-type and mutant strains. Plasmidome sequencing indicated that both strains harbored 7 plasmids with sizes ranging from 6,108 bp to 287,745 bp. Among the 7 plasmids, 6 were identical, and pMEA02' in strain MEA3-1Mut lost a 37,000-bp fragment compared to pMEA02 in strain MEA3-1. Two-dimensional electrophoresis (2-DE) and protein mass fingerprinting (PMF) showed that MEA3-1Mut lost the two-component flavin-dependent monooxygenase (TC-FDM) MeaBA, which was encoded by a gene in the lost fragment of pMEA02. MeaA shared 22% to 25% amino acid sequence identity with oxygenase components of some TC-FDMs, whereas MeaB showed no sequence identity with the reductase components of those TC-FDMs. Complementation with meaBA in MEA3-1Mut and heterologous expression in Pseudomonas putida strain KT2440 resulted in the production of an active MEHQ monooxygenase.
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Gutowski L, Olsson O, Leder C, Kümmerer K. A comparative assessment of the transformation products of S-metolachlor and its commercial product Mercantor Gold(®) and their fate in the aquatic environment by employing a combination of experimental and in silico methods. THE SCIENCE OF THE TOTAL ENVIRONMENT 2015; 506-507:369-379. [PMID: 25460972 DOI: 10.1016/j.scitotenv.2014.11.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 11/05/2014] [Accepted: 11/05/2014] [Indexed: 06/04/2023]
Abstract
Even appropriately used, pesticides can enter the surface and groundwater by several routes where photochemical degradation along with biotic processes contributes to their fate, resulting sometimes in the formation of stable transformation products (TPs). Yet, little is known about S-metolachlor (SM) transformation in the aquatic environment. Furthermore, commercial formulation of a pesticide might have different physical and biological properties compared to its pure grade. The present study assessed the biodegradability of the pure SM and its commercial product Mercantor Gold(®) (MG) by employing two OECD biodegradation (301D, F) tests. Photolysis in water was investigated by using a Xe lamp. Subsequently the biodegradability of the photolysis mixtures was examined. The primary elimination of SM was monitored and structures of its TPs were elucidated by HPLC-UV-MS/MS. Additionally, a set of in silico prediction programs was applied for supporting analytical results and toxicity assessment of SM and TPs. S-metolachlor and Mercantor Gold(®) were not biodegraded. HPLC-UV analysis showed higher elimination of SM in MG compared to pure SM during photolysis. A total of 10 photo-TPs of SM and MG were identified. According to MS data and in silico predictions, chemical structures were proposed for all found photo-TPs. Likewise for the parent compounds, no biodegradation has been observed for their photo-TPs. However, in the 301F test new bio-TPs have been generated from photo-TPs which were observed for the first time according to authors' best knowledge. The results suggest that the MG formulation does not affect the biodegradation process, but it influences the photolysis efficiency and potentially might result in faster formation of TPs in the environment. This study also demonstrates that photo-TPs can be further transformed into new products due to bacterial activity in the water phase. Moreover biotransformation might lead to an increased toxicity compared with the parent compound.
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Affiliation(s)
- Lukasz Gutowski
- Sustainable Chemistry and Material Resources, Institute of Sustainable and Environmental Chemistry, Leuphana University Lüneburg, C13, DE-21335 Lüneburg, Germany.
| | - Oliver Olsson
- Sustainable Chemistry and Material Resources, Institute of Sustainable and Environmental Chemistry, Leuphana University Lüneburg, C13, DE-21335 Lüneburg, Germany.
| | - Christoph Leder
- Sustainable Chemistry and Material Resources, Institute of Sustainable and Environmental Chemistry, Leuphana University Lüneburg, C13, DE-21335 Lüneburg, Germany.
| | - Klaus Kümmerer
- Sustainable Chemistry and Material Resources, Institute of Sustainable and Environmental Chemistry, Leuphana University Lüneburg, C13, DE-21335 Lüneburg, Germany.
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A derivative photoelectrochemical sensing platform for herbicide acetochlor based on TiO2–poly (3-hexylthiophene)–ionic liquid nanocomposite film modified electrodes. Talanta 2014; 127:169-74. [DOI: 10.1016/j.talanta.2014.01.058] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 01/22/2014] [Accepted: 01/25/2014] [Indexed: 11/19/2022]
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13
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Richardson SD, Ternes TA. Water analysis: emerging contaminants and current issues. Anal Chem 2014; 86:2813-48. [PMID: 24502364 DOI: 10.1021/ac500508t] [Citation(s) in RCA: 479] [Impact Index Per Article: 47.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Susan D Richardson
- Department of Chemistry and Biochemistry, University of South Carolina , Columbia, South Carolina 29208, United States
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