RESUMO
Methyl parathion is an organophosphorus pesticide widely employed worldwide to control pests in agricultural and domestic environments. However, due to its intensive use, high toxicity, and environmental persistence, methyl parathion is recognized as an important ecosystem and human health threat, causing severe environmental pollution events and numerous human poisoning and deaths each year. Therefore, identifying and characterizing microorganisms capable of fully degrading methyl parathion and its degradation metabolites is a crucial environmental task for the bioremediation of pesticide-polluted sites. Burkholderia zhejiangensis CEIB S4-3 is a bacterial strain isolated from agricultural soils capable of immediately hydrolyzing methyl parathion at a concentration of 50 mg/L and degrading the 100% of the released p-nitrophenol in a 12-hour lapse when cultured in minimal salt medium. In this study, a comparative proteomic analysis was conducted in the presence and absence of methyl parathion to evaluate the biological mechanisms implicated in the methyl parathion biodegradation and resistance by the strain B. zhejiangensis CEIB S4-3. In each treatment, the changes in the protein expression patterns were evaluated at three sampling times, zero, three, and nine hours through the use of two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), and the differentially expressed proteins were identified by mass spectrometry (MALDI-TOF). The proteomic analysis allowed the identification of 72 proteins with differential expression, 35 proteins in the absence of the pesticide, and 37 proteins in the experimental condition in the presence of methyl parathion. The identified proteins are involved in different metabolic processes such as the carbohydrate and amino acids metabolism, carbon metabolism and energy production, fatty acids ß-oxidation, and the aromatic compounds catabolism, including enzymes of the both p-nitrophenol degradation pathways (Hydroquinone dioxygenase and Hydroxyquinol 1,2 dioxygenase), as well as the overexpression of proteins implicated in cellular damage defense mechanisms such as the response and protection of the oxidative stress, reactive oxygen species defense, detoxification of xenobiotics, and DNA repair processes. According to these data, B. zhejiangensis CEIB S4-3 overexpress different proteins related to aromatic compounds catabolism and with the p-nitrophenol degradation pathways, the higher expression levels observed in the two subunits of the enzyme Hydroquinone dioxygenase, suggest a preferential use of the Hydroquinone metabolic pathway in the p-nitrophenol degradation process. Moreover the overexpression of several proteins implicated in the oxidative stress response, xenobiotics detoxification, and DNA damage repair reveals the mechanisms employed by B. zhejiangensis CEIB S4-3 to counteract the adverse effects caused by the methyl parathion and p-nitrophenol exposure.
Assuntos
Dioxigenases , Metil Paration , Praguicidas , Aminoácidos , Burkholderiaceae , Carboidratos , Carbono , Ecossistema , Ácidos Graxos , Hidroquinonas/análise , Metil Paration/análise , Metil Paration/química , Metil Paration/toxicidade , Nitrofenóis , Compostos Organofosforados , Proteômica , Espécies Reativas de Oxigênio , SoloRESUMO
Through the use of an enrichment technique, we isolated from the agricultural soils of Morelos in central México a strain of Burkholderia zhejiangensis identified as CEIB S4-3, it's could use the pesticide methyl parathion (MP) as the only source of carbon and degrade completely p-nitrophenol (PNP). For more efficient MP and PNP degradation by the CEIB S4-3 strain, the absence of an extra carbon source, a large inoculum and an MP concentration up to 50 mg/l are required. Sequence and annotation analysis of the draft genome, showed presence of mpd functional gene, which was expressed and its activity on the MP was confirmed. Additionally, the genes coding for enzymes in the benzoquinone pathway (conducted by Gram-negative bacteria) and the benzenotriol pathway (conducted by Gram-positive bacteria) were found, which was corroborated by identification of intermediary metabolites by HPLC. Thus, we propose that B. zhejiangensis CEIB S4-3 uses both degradation pathways.
Assuntos
Burkholderia/isolamento & purificação , Burkholderia/metabolismo , Metil Paration/metabolismo , Praguicidas/metabolismo , Microbiologia do Solo , Agricultura , Biodegradação Ambiental , Burkholderia/classificação , Burkholderia/genética , Cromatografia Líquida de Alta Pressão , Metil Paration/análise , Nitrofenóis/análise , Nitrofenóis/metabolismo , Praguicidas/análise , Solo/químicaRESUMO
This article discusses the adsorption of four organophosphorus pesticides-diazinon, dimethoate, methyl parathion, and sulfotep-in soil samples from four sites-Komchén, Xcanatún, Chablekal and Mocochá- in the northwest of Yucatan, Mexico. These pesticides have been detected in groundwater at concentrations greater than 5 (µg/L) during recent monitoring campaigns in the study area. In this region, groundwater contamination is exacerbated by its karst aquifer, which is susceptible to contamination and is considered very vulnerable. The experimental work was carried out using the batch equilibrium technique. Pesticide analyses by solid-phase extraction and gas chromatography were performed. The equilibrium adsorption data were analyzed by Henry, Langmuir and Freundlich models. The results indicate that the Freundlich model provides the best correlation of the experimental data. Freundlich adsorption coefficients Kf were in the range of 1.62-2.35 for sulfotep, 2.43 to 3.25 for dimethoate, from 5.54 to 9.27 for methyl parathion, and 3.22 to 5.17 for diazinon. Freundlich adsorption coefficients were normalized to the content of organic carbon in the soil to estimate the sorption coefficient of organic carbon (KOC). KOC values were in the range of 9.45-71.80, indicated that four pesticides have low adsorption on the four studied soils, which represents a high risk of contamination to the aquifer.
Assuntos
Diazinon/análise , Dimetoato/análise , Metil Paration/análise , Compostos Organotiofosforados/análise , Praguicidas/análise , Fosfatos/química , Poluentes do Solo/análise , Adsorção , Carbono/química , Poluentes Ambientais , Recuperação e Remediação Ambiental , Água Subterrânea/química , México , Solo/químicaRESUMO
This work describes the optimization and validation of a method employing solid-liquid extraction with low temperature partitioning (SLE/LTP) together with analysis by gas chromatography with electron capture detection (GC/ECD) for the determination of nine pesticides (chlorothalonil, methyl parathion, procymidone, endosulfan, iprodione, λ-cyhalothrin, permethrin, cypermethrin, and deltamethrin) in lettuce. The method was found to be selective, accurate, and precise, with means recovery values in the range of 72.3-103.2%, coefficients of variation ⩽ 12%, and detection limits in the range 0.4-37 µg kg(-1). The matrix components significantly influence the chromatographic response of the analytes (above 10%). The optimized and validated method was applied to determine the residual concentrations of the fungicides iprodione and procymidone that had been applied to field crops of lettuce. The maximum residual concentrations of the pesticides in the lettuce samples were 13.6 ± 0.4 mg kg(-1) (iprodione) and 1.00 ± 0.01 mg kg(-1) (procymidone), on the day after application of the products.
Assuntos
Cromatografia Gasosa/métodos , Lactuca/química , Resíduos de Praguicidas/isolamento & purificação , Extração em Fase Sólida/métodos , Contaminação de Alimentos/análise , Metil Paration/análise , Metil Paration/isolamento & purificação , Nitrilas/análise , Nitrilas/isolamento & purificação , Resíduos de Praguicidas/análise , Piretrinas/análise , Piretrinas/isolamento & purificação , TemperaturaRESUMO
BACKGROUND: The organophosphorus insecticides, especially those based on methyl parathion as active principle, have been used extensively in the protection of rice in Maranhão State, in the north-east of Brazil. This paper describes the optimisation of a solid-phase microextraction (SPME) procedure in confined atmosphere (headspace, HS) for the determination of methyl parathion in rice organic samples by gas chromatography with mass spectrometry detection (GC/MS). RESULTS: The proposed HS-SPME-GC/MS method has been shown to be appropriate for direct analysis of the insecticide in polished rice, with satisfactory results for the following parameters: linearity (correlation coefficient 0.9985), sensitivity (LOD and LOQ of 0.026 and 0.078 µg kg(-1) respectively), precision (coefficients of variation between 6.1 and 22.4%) and accuracy (recoveries varying from 73.2 to 90.0%). Although the efficiency of the proposed GC/MS does not differ statistically (P < 0.05) from the conventional GC/NPD method, given its low cost, speed and also the fact that a minimum volume of toxic effluent is generated, this method can be considered an on-line procedure based on green chemistry. CONCLUSIONS: Thus, the analytical methodology satisfies the minimum requirements for control of residues of such insecticides in rice samples destined for human consumption.
Assuntos
Cromatografia Gasosa-Espectrometria de Massas/métodos , Metil Paration/análise , Oryza/química , Resíduos de Praguicidas/análise , Microextração em Fase Sólida/métodos , Inibidores da Colinesterase/análise , Inseticidas/análiseRESUMO
The immobilization of enzymes onto transducer support is a mature technology and has been successfully implemented to improve biocatalytic processes for diverse applications. However, there exists still need to design more sophisticated and specialized strategies to enhance the functional properties of the biosensors. In this work, a biosensor platform based on innovative fabrication strategy was designed, and employed for the detection of organophosphate (OP) in natural waters. The biosensor was prepared by incorporating acetylcholinesterase enzyme (AChE) to the graphite paste modified with tetracyanoquinodimethane (TCNQ) mediator, along with the use of a macroalgae (Cladaphropsis membranous) as a functional immobilization support. The novel immobilization design resulted in a synergic effect, and led to enhanced stability and sensitivity of the biosensor. The designed biosensor was used to analyze methyl parathion OP insecticide in water samples collected from a demonstrably contaminated lake of São Luis Island, Maranhão, Northeast of Brazil. Water analysis revealed that the aquatic ecosystem was polluted by sub-ppm concentrations of the OP insecticide, and a good correlation was found between values obtained through biosensor and GC-MS techniques. Our results demonstrated that macroalgae-biosensor could be used as a low-cost and sensitive screening method to detect target analyte.
Assuntos
Técnicas Biossensoriais/métodos , Inseticidas/análise , Metil Paration/análise , Alga Marinha/metabolismo , Poluentes Químicos da Água/análise , Acetilcolinesterase/química , Acetilcolinesterase/metabolismo , Animais , Brasil , Electrophorus , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Grafite/química , Humanos , Inseticidas/metabolismo , Limite de Detecção , Metil Paration/metabolismo , Nitrilas/química , Alga Marinha/química , Poluentes Químicos da Água/metabolismoRESUMO
Seven marine fungi strains (Aspergillus sydowii CBMAI 934, A. sydowii CBMAI 935, A. sydowii CBMAI 1241, Penicillium decaturense CBMAI 1234, Penicillium raistrickii CBMAI 931, P. raistrickii CBMAI 1235, and Trichoderma sp. CBMAI 932) were screened by their growth in the presence of methyl parathion (MP) in a solid culture medium. The strains with best growth were A. sydowii CBMAI 935 and P. decaturense CBMAI 1234. Biodegradation reactions were performed in 10, 20 and 30d in a malt extract liquid medium containing commercial MP and whole cells of A. sydowii CBMAI 935 and P. decaturense CBMAI 1234. In 20d, A. sydowii CBMAI 935 was able to degrade all pesticide, whereas P. decaturense CBMAI 1234 promoted a complete degradation in 30d. A. sydowii CBMAI 935 and P. decaturense CBMAI 1234 could degrade the product of the MP enzymatic hydrolysis, p-nitrophenol, on average of 51 and 40% respectively. Both strains used MP as a sole source of carbon and provided satisfactory results. Metabolites detected in the medium showed that the presumable reaction pathway occurred through the activation of MP to its more toxic form, methyl paraoxon, which was further degraded to p-nitrophenol.
Assuntos
Aspergillus/crescimento & desenvolvimento , Metil Paration/análise , Penicillium/crescimento & desenvolvimento , Microbiologia da Água , Poluentes Químicos da Água/análise , Biodegradação Ambiental , Hidrólise , Metil Paration/química , Estrutura Molecular , Oxirredução , Poluentes Químicos da Água/químicaRESUMO
An extraction method based on matrix solid-phase dispersion was developed to determine pirimicarb, methyl parathion, malathion, procymidone, alpha-endosulfan and beta-endosulfan in lettuce using gas chromatography-mass spectrometry. The best results were obtained using 4.0 g of lettuce, 2.0 g of silica as dispersant sorbent, 0.1 g of activated carbon as clean up sorbent and acetonitrile as eluting solvent. The method was validated using lettuce samples fortified with pesticides at six different concentration levels (0.1 to 2.0 mg/kg). Average recoveries (7 replicates) ranged from 50 to 120%, with relative standard deviations between 0.6 and 8.0%. Detection and quantification limits for lettuce ranged from 0.01 to 0.02 mg/kg and 0.04 to 0.10 mg/kg, respectively.
Assuntos
Carbamatos/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Hidrocarbonetos Clorados/análise , Lactuca/química , Compostos Organofosforados/análise , Resíduos de Praguicidas/análise , Acetonitrilas/química , Compostos Bicíclicos com Pontes/análise , Endossulfano/análise , Malation/análise , Metil Paration/análise , Pirimidinas/análise , Extração em Fase Sólida/métodos , Solventes/químicaRESUMO
This study investigated the removal of methyl parathion by cyanobacteria Microcystis novacekii in culture conditions and evaluated toxicity in terms of EC(50) of the pesticide for the species. This is the first report on the removal and toxicity of methyl parathion for the species that is abundant and easily accessible in Brazilian lakes. The results have shown that Microcystis novacekii is capable of removing methyl parathion, an organophosphorus pesticide, from the culture medium with an extraction rate higher than 90%. Spontaneous degradation was not significant, which indicates a high efficiency level of biological removal. No metabolites of methyl parathion were detected in the culture medium at the concentration levels evaluated (0.10 to 2.00 mg/dm(3)). The mechanisms proposed to explain pesticide removal are bioaccumulation and mineralization. EC(50) for 72 h was 17.60 mg/dm(3), which is much higher than the usual concentrations in surface waters. This indicates that M. novacekii is highly tolerant of this pesticide and may represent an important bioremediation agent of contaminated environments.
Assuntos
Inseticidas/metabolismo , Metil Paration/metabolismo , Microcystis/metabolismo , Biodegradação Ambiental , Meios de Cultura , Inseticidas/análise , Inseticidas/toxicidade , Metil Paration/análise , Metil Paration/toxicidade , Microcystis/efeitos dos fármacos , Testes de Toxicidade Aguda , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/metabolismo , Poluentes Químicos da Água/toxicidadeRESUMO
Methyl parathion (MeP), an insecticide commonly used in Mexico, has been detected in water bodies adjacent to agricultural crops and is accumulated in the tissue of the amarillo (Girardinichthys multiradiatus), a viviparous fish unique to Central Mexico. Evidence of MeP accumulation in a G. multiradiatus population prompted assessment of the consequences of exposure to MeP during the gestation period and adult life. We exposed adult fish to MeP in the diet at concentrations ranging from 0.001 to 0.165 microg/g dry weight of food. Fish accumulated MeP at concentrations from 0.21 to 5.87 microg/g of fish and exhibited a significant reduction in weight and growth rate. We also evaluated the effects on broods of pregnant females exposed to 0.005, 0.01, and 0.1 microg/g dry weight of food. Although these pregnant females were not affected, their offspring showed an increase in spinal cord malformation and a reduction in survival to adulthood. Finally, we sampled seven localities inhabited by G. multiradiatus; this revealed the presence of MeP in two water bodies at concentrations of 0.0036 and 0.037 microg/mL respectively. Our results suggest that low MeP concentrations affect immature fish with possible consequences later in life.
Assuntos
Ciprinodontiformes/anormalidades , Ciprinodontiformes/crescimento & desenvolvimento , Metil Paration/análise , Metil Paration/farmacologia , Viviparidade não Mamífera , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/farmacologia , Animais , Animais Recém-Nascidos , Feminino , Inseticidas/análise , Inseticidas/farmacologia , Masculino , México , Reprodução/efeitos dos fármacos , Medula Espinal/anormalidadesRESUMO
This paper describes the development and evaluation of a sequential injection method to automate the determination of methyl parathion by square wave adsorptive cathodic stripping voltammetry exploiting the concept of monosegmented flow analysis to perform in-line sample conditioning and standard addition. Accumulation and stripping steps are made in the sample medium conditioned with 40 mmolL(-1) Britton-Robinson buffer (pH 10) in 0.25 molL(-1) NaNO3. The homogenized mixture is injected at a flow rate of 10 microLs(-1) toward the flow cell, which is adapted to the capillary of a hanging drop mercury electrode. After a suitable deposition time, the flow is stopped and the potential is scanned from -0.3 to -1.0V versus Ag/AgCl at frequency of 250 Hz and pulse height of 25 mV. The linear dynamic range is observed for methyl parathion concentrations between 0.010 and 0.50 mgL(-1), with detection and quantification limits of 2 and 7 microgL(-1), respectively. The sampling throughput is 25 h(-1) if the in line standard addition and sample conditioning protocols are followed, but this frequency can be increased up to 61 h(-1) if the sample is conditioned off-line and quantified using an external calibration curve. The method was applied for determination of methyl parathion in spiked water samples and the accuracy was evaluated either by comparison to high performance liquid chromatography with UV detection, or by the recovery percentages. Although no evidences of statistically significant differences were observed between the expected and obtained concentrations, because of the susceptibility of the method to interference by other pesticides (e.g., parathion, dichlorvos) and natural organic matter (e.g., fulvic and humic acids), isolation of the analyte may be required when more complex sample matrices are encountered.
Assuntos
Eletroquímica/instrumentação , Eletroquímica/métodos , Água Doce/química , Metil Paration/análise , Poluentes Químicos da Água/análise , Adsorção , Automação , Eletrodos , Reprodutibilidade dos TestesRESUMO
The efficiency of a dark Fenton system (H2O2/Fe2+) to remove chlorothalonil from water, alone and in the presence of the organophosphorous pesticides methyl parathion and methamidophos, was evaluated. Here we show that the process is rapid and efficient. Nearly complete degradation of chlorothalonil and methyl parathion (98%) was observed in less than 10 min whereas methamidophos showed similar levels of efficiency only after 40 to 90 min. Formulating agents did not appear to impair the degradation of active ingredients. Interactions during the degradation of mixtures of the three pesticides only appeared to affect methamidophos degradation.
Assuntos
Peróxido de Hidrogênio/química , Ferro/química , Praguicidas/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Estudos de Avaliação como Assunto , Peróxido de Hidrogênio/análise , Metil Paration/análise , Metil Paration/química , Nitrilas/análise , Nitrilas/química , Compostos Organotiofosforados/análise , Compostos Organotiofosforados/química , Oxigênio/análise , Praguicidas/análiseRESUMO
Field trials were conducted in commercial agricultural areas in Brazil to determine the variability of residues of parathion methyl, diazinon and methidathion in individual units of large crops treated twice with a mixture of the three pesticides. Over 120 random samples were collected, extracted with ethyl acetate and residues determined by GC/FPD. The recoveries and their coefficient of variation were, in general, within the acceptable levels during sample analyses. Residues in papaya and mango were not affected by the position of the fruits in the plant, apparently more or less exposed to the pesticides. Variability factor ?, defined as the 97.5th percentile divided by the mean of residues in all samples taken from a field ranged from 2.0-2.6. The variability of residues within the plant contributed to about 34-61% of the field variability. The results found in this study support the variability factor of 3 adopted by the FAO/WHO for the deterministic estimation of dietary acute intake of pesticides.
Assuntos
Inseticidas/análise , Magnoliopsida/química , Compostos Organofosforados/análise , Resíduos de Praguicidas/análise , Poluentes do Solo/análise , Agricultura , Brasil , Carica/química , Cromatografia Gasosa/métodos , Cucurbita/química , Diazinon/análise , Mangifera/química , Metil Paration/análise , Compostos Organotiofosforados/análiseRESUMO
Methyl parathion (MeP) is a very hazardous pesticide freely used in agriculture in Mexico. This pesticide and others, arriving through different processes, exert significant effects on water quality with serious consequences for environmental and human health. This study evaluates the removal efficiency of common cattail Typha latifolia L. on MeP in water and artificial sediments. The effects of the pesticide on this macrophyte after 10 days of exposure were determined using a concentration range of 0-200 mg l(-1), 198.1+/-1.79 g average biomass, pH 7.0, 18-22 degrees C temperature and natural daylight/darkness periods, using chlorophyll production as a biomarker. Removal kinetics were conducted under similar conditions on days 0, 3, 7, 9, 11 and 14 of exposure, using 6 mg l(-1) in each system. Pesticide concentration, chlorophyll content and glutathione S-transferase (GST) activity were quantified. Results show a high removal efficiency of cattails on MeP in water and sediments relative to controls. An increase in GST activity and a decline in chlorophyll content in the test systems were not significantly different relative to controls. Cattails may thus be a good candidate for development of a phytoremediation system for MeP-contaminated water and artificial sediments.
Assuntos
Sedimentos Geológicos/química , Metil Paration , Poluentes do Solo , Typhaceae/crescimento & desenvolvimento , Poluentes Químicos da Água , Biodegradação Ambiental , Cinética , Metil Paration/análise , Metil Paration/toxicidade , Poluentes do Solo/análise , Poluentes do Solo/toxicidade , Typhaceae/efeitos dos fármacos , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidadeRESUMO
The objective of this research was to study the residual levels of benomyl, methyl parathion, diuron, and vamidothion in pineapple bagasse and pulp. Benomyl (benlate), methyl parathion (Folidol 600), diuron (Krovar), and Vamidothion (Kilval 300) were applied pre-harvest to pineapples (smooth cayenne). After harvesting, the fruits were washed (100 ppm sodium hypochlorite) and the pulp was separated from the sub-products (peel, core, tops, and tails). The pulp was not submitted to any heat treatment. The sub-products and the juice expressed from them, were submitted to a blanching process (95 degrees C for 1 min). After separating the juice, the bagasse and pulp were analyzed for residues of diuron and benomyl by high performance liquid chromatography, and for residues of vamidothion and methyl parathion by gas chromatography using a TSD detector. No residues of benomyl, diuron, vamidothion, or methyl parathion were detected in the pulp within the quantification limits of the methods (0.1 mg/kg, 0.1 mg/kg, 0.005 mg/kg, and 0.005 mg/kg, respectively). Only methyl parathion (0.052 mg/kg) and vamidothion (0.021 mg/kg) were detected in the bagasse. The presence of these residues in the bagasse was probably due to the action of the wax found in the peel, which prevented the methyl parathion and vamidothion from dissolving in the juice. According to these results, the pulp was fit for human consumption, as far as pesticide residues were concerned, and the bagasse was fit for animal feed and similar applications, because the residual levels found were below the limits established for these compounds.
Assuntos
Benomilo/análise , Celulose/química , Diurona/análise , Frutas/química , Metil Paration/análise , Compostos Organotiofosforados/análise , Resíduos de Praguicidas/análise , Cromatografia Gasosa , Cromatografia Líquida de Alta Pressão , Humanos , Inseticidas/análiseRESUMO
This paper reports on the residues of methyl parathion (O,O-dimethyl O-4-nitrophenyl phosphorothioate), trifluralin (alpha, alpha, alpha-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine), endosulfan [(1, 4, 5, 6, 7, 7-hexachloro-8, 9, 10-trinorborn-5-en-2, 3-ylenebismethylene) sulfite] and dimethoate (O, O-dimethyl S-methylcarbamoylmethyl phosphorodithioate) in a cotton crop soil. Soil samples (0-15 cm) were collected at different periods from the cotton crop farm and subjected to Soxhlet extraction. The extracted material was analysed after clean-up by a HP5890 II gas chromatograph equipped with a 63Ni electron-capture detector (ECD-63Ni) and fitted with a 25 m x 0.2 mm i.d. fused silica capillary column [Ultra-2 (5% phenylmethyl polysiloxane)]. The recoveries of the pesticide residues from the spiked control soil were determined after Soxhlet extraction and C18 cartridges clean-up by using radiotracer techniques with the corresponding 14C-pesticides. The results show that in the cotton crop soil the pesticide residues under study were present in the range of 0.1 to 0.4 mg.kg-1. Endosulfan was found to be rapidly degraded in the soil and formed a sulfate metabolite.