RESUMO
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
The multi-xenobiotics resistance (MXR) mechanisms are the first line of defense against toxic substances in aquatic organisms and present great importance in the adaptation related to contaminated environments. Methyl parathion (MP) is a widely used organophosphate pesticide, which has been associated to various toxic effects in organisms. In the present work, we studied the main genes related to efflux transporters in zebrafish liver (ZFL) cells exposed to MP with and without an inhibitor of ABC transporters (verapamil). The results concerning transporters activity showed that the MXR mechanism is activated to detoxify from methyl parathion. The toxic effects of MP on ZFL cells were increased in the presence of the efflux transporter inhibitor, once cell viability was significantly decreased in co-exposure experiments. The combined exposure to MP and the inhibitor caused an increase in gene expression of P-gp1 (Abcb1) and MRP4 (Abcc4), suggesting that these transporters isoforms are associated with MP efflux. In general, the expression of genes related to the antioxidant defense system (ADS) was significantly increased in ZFL cells co-exposed to MP and verapamil. These data provide useful insights for better understanding of MP detoxification mechanism in fish hepatocytes.
Assuntos
Fígado/metabolismo , Metil Paration/metabolismo , Proteínas Associadas à Resistência a Múltiplos Medicamentos/fisiologia , Proteínas de Peixe-Zebra/fisiologia , Transportadores de Cassetes de Ligação de ATP , Animais , Linhagem Celular , Sobrevivência Celular , Relação Dose-Resposta a Droga , Fígado/fisiologia , Proteínas Associadas à Resistência a Múltiplos Medicamentos/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Peixe-Zebra/metabolismo , Proteínas de Peixe-Zebra/metabolismoRESUMO
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
We investigated the diversity of a denitrifying gene (nirK) and the emission of CO(2) and N(2)O, in a "chinampa" soil contaminated with methyl parathion. Soil at 40% of water holding capacity was spiked with methyl parathion at four concentrations (i.e. 0, 0.7, 1.47 and 4.27 g kg(-1) dry soil), while emission of N(2)O and CO(2) and nirK diversity was determined after 0, 1, 14, 30, 60 and 90 days. The emission of N(2)O on a daily base and the cumulative emission of CO(2) was not affected by the different concentrations of methyl parathion applied to soil. The diversity of the nirK gene, determined by using temperature gradient gel electrophoresis (TGGE), decreased with increased methyl parathion application. It was found that methyl parathion had effect on the emissions of N(2)O and CO(2), and reduced the diversity of the nirK gene. Consequently, the reduced diversity of the nirK gene could affect the emission of N(2)O.
Assuntos
Inseticidas/metabolismo , Metil Paration/metabolismo , Óxido Nitroso/metabolismo , Microbiologia do Solo , Poluentes do Solo/metabolismo , Dióxido de Carbono/metabolismo , Desnitrificação , Eletroforese/métodos , Genes Bacterianos , México , Dados de Sequência Molecular , FilogeniaRESUMO
A tezontle-packed up-flow reactor (TPUFR) with an immobilized bacterial consortium for biological treatment of methyl-parathion and tetrachlorvinphos was evaluated. These organophosphate pesticides are widely used in Mexico for insect and mite control, respectively. With the aim of developing a tool for pesticide biodegradation, four flow rates (0.936, 1.41, 2.19, and 3.51 l/h) and four hydraulic residence times (0.313, 0.206, 0.133, and 0.083 h) were evaluated in a TPUFR. In the bioreactor, with an operating time of 8 h and a flow of 0.936 l/h, we obtained 75% efficiency in the removal of methyl-parathion and tetrachlorvinphos. Their adsorptions in the volcanic rock were 9% and 6%, respectively. It was demonstrated that the removal of pesticides was due to the biological activity of the immobilized bacterial consortium. We confirmed the decrease in toxicity in the treated effluent from the bioreactor through the application of acute toxicity tests on Eisenia foetida. Immobilization of a bacterial consortium using tezontle as a support is innovative and an economical tool for the treatment of mixtures of organophosphorus pesticide residues.
Assuntos
Bactérias/metabolismo , Biodegradação Ambiental , Poluição Ambiental/prevenção & controle , Metil Paration/metabolismo , Oligoquetos/efeitos dos fármacos , Praguicidas/metabolismo , Tetraclorvinfos/metabolismo , Adsorção , Animais , Reatores Biológicos , Células Imobilizadas , México , Consórcios Microbianos/fisiologia , Oligoquetos/fisiologia , Porosidade , Erupções VulcânicasRESUMO
A bacterial consortium with the ability to degrade methyl parathion and p-nitrophenol, using these compounds as the only carbon source, was obtained by selective enrichment in a medium with methyl parathion. Samples were taken from Moravia, Medellin; an area that is highly contaminated, owing to the fact that it was used as a garbage dump from 1974 to 1982. Acinetobacter sp, Pseudomonas putida, Bacillus sp, Pseudomonas aeruginosa Citrobacter freundii, Stenotrophomonas sp, Flavobacterium sp, Proteus vulgaris, Pseudomonas sp, Acinetobacter sp, Klebsiella sp and Proteus sp were the microorganisms identified within the consortium. In culture, the consortium was able to degrade 150 mg L⻹ of methyl-parathion and p-nitrophenol in 120 h, but after adding glucose or peptone to the culture, the time of degradation decreased to 24 h. In soil, the consortium was also able to degrade 150 mg L⻹ of methyl parathion in 120 h at different depths and also managed to decrease the toxicity.
Assuntos
Bactérias/isolamento & purificação , Bactérias/metabolismo , Metil Paration/metabolismo , Consórcios Microbianos , Nitrofenóis/metabolismo , Microbiologia do Solo , Poluentes do Solo/metabolismo , Bactérias/química , Biodegradação Ambiental , Cinética , Metil Paration/química , Nitrofenóis/química , Poluentes do Solo/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
The interaction of methyl-parathion with serum and albumin of pacu, Piaractus mesopotamicus, was studied, using the fluorescence quenching technique. Pacu is a neo-tropical fish specie inhabitant of rivers from western regions of Brazil. Methyl-parathion (O,O-dimethyl O-p-nitrophenyl phosphorothioate) is an organophosphorous pesticide still used in agriculture and fish farming in many countries. The quenching of fluorescence can be mathematically expressed by the Stern-Volmer equation to calculate quenching constants. Stern-Volmer curves analysis is able to give important information about the pesticide-albumin interaction. Our results showed that the serum quenching reached 10% when the molar ratio of pesticide/albumin was about 7:1 for the three temperatures of the experiment. For the pure albumin quenching of 10%, methyl-parathion concentrations were 6, 7 and 9 times higher than albumin at 20, 25 and 30 degrees C, respectively. The calculated Stern-Volmer constants at 25 degrees C were 9.73x10(3)(+/-4.9x10(2))M(-1) for serum and 9.20x10(3)(+/-2.0x10(2))M(-1) for albumin. It was observed that albumin quenching is the phenomenon contributing to the quenching of the pacu serum fluorescence for methyl-parathion concentration lower than 10microM, suggesting that the protein is the most important carrier for the pesticide in serum.
Assuntos
Peixes/sangue , Inseticidas/metabolismo , Metil Paration/metabolismo , Albumina Sérica/metabolismo , Animais , Proteínas Sanguíneas/análise , Fluorescência , Ligação Proteica , Albumina Sérica/análiseRESUMO
The interaction of methyl-parathion with the albumin of Piaractus mesopotamicus (Holmberg 1887) (= pacu), a fish species typical of Brazilian rivers, was studied and the results compared with known values for human and bovine albumin obtained in an earlier investigation. Methyl-parathion (O,O-dimethyl O-p-nitrophenyl phosphorothioate) is an organophosphorous pesticide still used in agriculture and fish farming in many countries. The fluorescence quenching technique with tryptophan as a natural probe was used to detect for the presence of methyl-parathion. Fluorescence can be mathematically expressed by the Stern-Volmer equation to calculate quenching constants, and changes in the behavior of Stern-Volmer curves at different temperatures indicate the nature of the mechanism causing the quenching. Our results indicate that methyl-parathion forms a complex with fish albumin. The estimated association constant is 9.73 x 103 (+/- 4.9 x 102) M(-1) at 25 degrees C.
Assuntos
Peixes/metabolismo , Inseticidas/metabolismo , Metil Paration/metabolismo , Albumina Sérica/metabolismo , Animais , Bovinos , Fluorescência , Humanos , Modelos Biológicos , Especificidade da Espécie , Espectrofotometria Ultravioleta , Temperatura , TriptofanoRESUMO
The aim of this study was to determine the efficiency of Dugesia dorotocephala on Methyl parathion removal. An initial concentration of 1.25 microg mL(-1) of MeP was used to evaluate the removal capacity of planarian. A first-order removal kinetics was obtained with a disappearance rate constant (k(r)) of 0.49 days(-1) and 69% efficiency on contaminant removal. This is significantly different (p < 0.5) from the degradation occurring in control systems, leading us to conclude that D. dorotocephala effectively removes MeP from contaminated water.