Influência do herbicida Gesapax na atividade microbiana do solo e sua ecotoxicidade
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Data
2017-05-16
Autores
Régo, Ana Paula Justiniano [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
O herbicida Gesapax® (ingrediente ativo: ametrina) é utilizado em culturas de cana-de-açúcar para o combate a plantas daninhas. Devido as suas propriedades físico-químicas é encontrado com frequência nos corpos hídricos. Ao adicionar surfactantes químicos ao solo contaminado com compostos orgânico, ocorre uma diminuição da tensão superficial entre o contaminante e a fração solúvel do solo, favorecendo a degradação de compostos orgânicos, uma vez que o mesmo fica de maneira biodisponível à microbiota. Dessa forma, neste trabalho teve por objetivo avaliar a influência do herbicida Gesapax na atividade microbiana em amostras de solo, utilizando o surfactante químico Tween 80, como em forma de bioestimulação e adição de consórcio microbiano como forma de bioaumentação, a fim de atuarem como coadjuvantes no processo de metabolização do herbicida. Avaliou-se a atividade microbiana utilizando frascos respirométricos de Bartha e Pramer e utilizando a técnica de colorimetria com DCPIP. Fez-se a análise da biodegradação do herbicida por meio de ensaio de cromatografia (HPLC) em amostras retiradas dos respirometros. Também, avaliou-se a toxicidade do solo com o herbicida através dos organismos testes Saccharomyces cerevisiae, sementes de Lactuca sativa, Eruca sativa e Cucumis sativus, e a mutagenicidade em amostras de solo com a Tradescantia pallida (coração púrpura). Fez-se também a quantificação de bactérias e fungos do solo, finalizando com ensaio de biologia molecular, a fim de avaliar a perturbação da presença do herbicida no solo para a estrutura microbiana nos tratamentos. A adição de surfactante ao solo contaminado com herbicida, possibilitou grande aumento da atividade microbiana, em comparação ao solo controle. O mesmo ocorreu nos tratamentos com herbicida e consórcio microbiano. O herbicida foi metabolizado na presença do surfactante e consórcio microbiano. Também houve aumento na quantificação da microbiota do solo na presença desses coadjuvantes da biodegradação e nos ensaios ecotoxicológicos, com sementes diminuiu o potencial tóxico do Gesapax para os outros organismos testes. Por fim, nos ensaios moleculares, por meio de métodos independentes de cultivo, possibilitou observar o impacto do herbicida para a comunidade microbiana, causando grande perturbação no solo. No tratamento que continha herbicida e consórcio microbiano e surfactante causou maior diversificação da comunidade, concluindo que as bactérias atuaram como principal responsável na biodegradação do herbicida Gesapax em solo, sendo auxiliada pela utilização do surfactante, que acelerou a degradação, bioestimulando a microbiota do solo, além de ser viável para aplicação em campo. Portanto, a utilização de surfactante e consórcio microbiano auxiliou intensamente a metabolização do herbicida, diminuindo os riscos ecotoxicológicos provenientes da sua molécula, promovendo a desintoxicação do solo.
The herbicide Gesapax® (active ingredient: ametryne) is used in sugarcane crops to combat weeds. Due to its physico-chemical properties it is frequently found in water bodies. By adding chemical surfactants to the soil contaminated with organic compounds, there is a decrease in the surface tension between the contaminant and the soluble fraction of the soil, favoring the degradation of organic compounds, in a bio-available way. Thus, the objective of this work was to evaluate the influence of the Gesapax herbicide on microbial activity in soil samples, using the chemical surfactant Tween 80, as in the form of biostimulation and addition of microbial consortium as a form of bioaumentation, to act as adjuvants in the process of metabolizing the herbicide. Microbial activity was evaluated using Bartha and Pramer respirometric flasks and using the DCPIP colorimetric technique. The biodegradation of the molecule was analyzed by chromatography assay (HPLC) on samples taken from the respirometers. Soil toxicity with the herbicide was evaluated through the test organisms Saccharomyces cerevisiae, seeds of Lactuca sativa, Eruca sativa and Cucumis sativus, mutagenicity in soil samples with Tradescantia pallida (purple heart), quantification of bacteria and fungi soil, finishing with molecular biology assay, to evaluate the perturbation of the presence of the herbicide in the soil to the microbial structure in the treatments. The addition of surfactant to the soil contaminated with herbicide, allowed a great increase of the microbial activity, in comparison to the control soil. The same occurred in the treatments with herbicide and microbial consortium. The herbicide was metabolized in the presence of the surfactant and microbial consortium. There was also an increase in the quantification of the soil microbiota in the presence of these biodegradation coadjutant’s and in the ecotoxicological tests, with seeds decreased the toxic potential of the Gesapax for the other test organisms. Finally, in the molecular tests, through independent cultivation methods, it was possible to observe the impact of the herbicide on the microbial community, causing great perturbation in the soil. However, in the treatment that contained herbicide and microbial consortium and surfactant caused a greater diversification of the community, concluding that the bacteria acted as the main responsible in the biodegradation of the herbicide Gesapax in soil, being aided using surfactant, which accelerated the degradation, biostimulating the microbiota of the soil, besides being feasible for field application. Therefore, the use of surfactant and microbial consortium helped intensively the metabolization of the herbicide, reducing the ecotoxicological risks of its molecule, promoting the detoxification of the soil.
The herbicide Gesapax® (active ingredient: ametryne) is used in sugarcane crops to combat weeds. Due to its physico-chemical properties it is frequently found in water bodies. By adding chemical surfactants to the soil contaminated with organic compounds, there is a decrease in the surface tension between the contaminant and the soluble fraction of the soil, favoring the degradation of organic compounds, in a bio-available way. Thus, the objective of this work was to evaluate the influence of the Gesapax herbicide on microbial activity in soil samples, using the chemical surfactant Tween 80, as in the form of biostimulation and addition of microbial consortium as a form of bioaumentation, to act as adjuvants in the process of metabolizing the herbicide. Microbial activity was evaluated using Bartha and Pramer respirometric flasks and using the DCPIP colorimetric technique. The biodegradation of the molecule was analyzed by chromatography assay (HPLC) on samples taken from the respirometers. Soil toxicity with the herbicide was evaluated through the test organisms Saccharomyces cerevisiae, seeds of Lactuca sativa, Eruca sativa and Cucumis sativus, mutagenicity in soil samples with Tradescantia pallida (purple heart), quantification of bacteria and fungi soil, finishing with molecular biology assay, to evaluate the perturbation of the presence of the herbicide in the soil to the microbial structure in the treatments. The addition of surfactant to the soil contaminated with herbicide, allowed a great increase of the microbial activity, in comparison to the control soil. The same occurred in the treatments with herbicide and microbial consortium. The herbicide was metabolized in the presence of the surfactant and microbial consortium. There was also an increase in the quantification of the soil microbiota in the presence of these biodegradation coadjutant’s and in the ecotoxicological tests, with seeds decreased the toxic potential of the Gesapax for the other test organisms. Finally, in the molecular tests, through independent cultivation methods, it was possible to observe the impact of the herbicide on the microbial community, causing great perturbation in the soil. However, in the treatment that contained herbicide and microbial consortium and surfactant caused a greater diversification of the community, concluding that the bacteria acted as the main responsible in the biodegradation of the herbicide Gesapax in soil, being aided using surfactant, which accelerated the degradation, biostimulating the microbiota of the soil, besides being feasible for field application. Therefore, the use of surfactant and microbial consortium helped intensively the metabolization of the herbicide, reducing the ecotoxicological risks of its molecule, promoting the detoxification of the soil.
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Palavras-chave
Gesapax, Consórcio microbiano, Surfactante, Biodegradação, Microbial consortium, Surfactant, Biodegradation