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Previous issue date: 2016-03-07 / O uso abusivo de glifosato, um dos agrot?xicos mais utilizados no Brasil, est? relacionado a problemas de sa?de e ao ambiente. Diante disso, o presente trabalho teve como objetivo isolar, avaliar a capacidade de crescimento ou degrada??o e posteriormente identificar microrganismos aut?ctones degradadores de glifosato de um solo com uso intensivo deste agrot?xico. Foram coletadas 12 amostras de solo aleatoriamente (0-10 cm de profundidade), homogeneizadas e ap?s transferido 1 g da amostra para erlenmeyer contendo 50 mL de meio mineral (MM) (g/L, KCl 0,7; KH2PO4 2,0; Na2HPO4 3,0; NH4NO3 1,0; MgSO4 1,0; FeSO4 4,0; MnCl2 0,2; CaCl2 0,2; pH 7,2) com 100 mg/L de glifosato (?nica fonte de carbono) com 3 transfer?ncias subsequentes (1 mL) a cada cinco dias, incubando a 28 ?C. Ap?s, foi realizada a contagem em placas e as bact?rias e fungos morfologicamente diferentes foram isolados em ?gar nutriente e sabouraud com 300 mg/L de glifosato, respectivamente. A seguir, os fungos foram incubados em ?gar MM s?lido com 300 mg/L de glifosato, como ?nica fonte de carbono, a 28 ?C/14 dias. Foi realizada a medida di?ria do crescimento micelial radial e calculada a velocidade de crescimento por meio de regress?o linear dos raios das col?nias. Do total de 18 fungos isolados, 11 utilizaram o glifosato como fonte de carbono. Foram identificados oito g?neros de fungos filamentosos e dois falsos fungos, que apresentaram as maiores velocidades de crescimento radial. Os g?neros que mais se destacaram foram: Aspergillus sp., Fusarium sp., Penicillium sp. e Geotrichum sp. Foram isoladas 25 bact?rias (47% bacilos gram negativas), destas, seis permaneceram vi?veis at? o experimento de degrada??o de glifosato. Para o preparo do in?culo bacteriano, uma al?ada foi transferida para erlenmeyers com 100 mL de caldo nutriente e 300 mg/L de glifosato, incubado a 150 rpm/48 h. Ap?s tr?s lavagens (MM), o in?culo foi padronizado (escala de McFarland). O ensaio do potencial de degrada??o das bact?rias isoladas foi realizado com a incuba??o do in?culo (5x106 UFC/mL) em MM na aus?ncia/presen?a de diferentes concentra??es de glifosato (300, 500 e 700 mg/L) utilizando o indicador redox 2,6-diclorofenol-indofenol (DCPIP), incubadas em estufa (28 ?C) e realizadas medidas espectrofotom?tricas a 600 nm no per?odo de 0-120h. As 6 bact?rias testadas apresentaram velocidade degrada??o de DCPIP nas concentra??es testadas, indicando que possivelmente utilizaram o glifosato como fonte de carbono. A bact?ria B8, relativamente ?s demais, foi a que mais reduziu a quantidade de DPCIP. Os resultados sugerem que os microrganismos isolados s?o tolerantes e apresentam alto potencial de degrada??o de glifosato, podendo ser utilizados em futuros estudos de biorremedia??o de solos contaminados com este agrot?xico. / The abusive use of glyphosate, one of the most widely used pesticides in Brazil is related to health issues and the environment. Therefore, this study aimed to isolate, evaluate the growth capacity or degradation and subsequently identify indigenous microorganisms degrading glyphosate in a soil with intensive use of this pesticide. The 12 samples were collected randomly soil (0-10 cm depth), homogenized and them 1 g of the sample was transferred in a flask containing 50 ml of mineral medium (MM) (g/L KCl 0.7; KH2PO4 2.0; Na2HPO4, 3.0; NH4NO3 1.0; MgSO4 1.0; FeSO4 4.0; MnCl2, 0.2; CaCl2 0.2; pH 7.2) with 100 mg/L glyphosate (as sole carbon source) 3 subsequent transfers (1 ml) every five days and incubation at 28 ? C. Bacteria and fungi morphologically different were isolated on nutrient agar, and Sabouraud with 300 mg/L of glyphosate, respectively. The following fungi were incubated on solid MM agar with 300 mg/l glyphosate as sole carbon source at 28 ? C by 14 days. The radial mycelial growth was daily measured and the growth rate were calculated by linear regression using the colonies rays. Of the total of 18 fungal isolates, 11 used glyphosate as a carbon source. eight genera of filamentous fungi and two false fungi, with the highest rates of radial growth were identified. The genres that stood out were: Aspergillus, Fusarium sp, Penicillium sp... and Geotrichum sp. 25 Bacteria were isolated (47% gram-negative bacilli), these six remained viable by the experiment of glyphosate degradation. To prepare the inoculum, was transferred to a Erlenmeyer flasks with 100 ml of nutrient broth and 300 mg/L of glyphosate, incubated at 150 rpm by 48 h. After three washes (MM), the inoculum was standardized using McFarland scale. The potential for degradation of the test isolates was performed with incubation inoculum (5x106 CFU/ml) in MM in the absence or presence of different concentrations of glyphosate (300, 500 and 700 mg/L) using redox indicator 2,6-dichlorophenol-indophenol (DCPIP), incubated in a greenhouse (28 ?C) and spectrometric measured at 600 nm in 0-120h period. The 6 bacterial strains tested showed DCPIP degradation rate at the concentrations tested, indicating that possibly used glyphosate as a carbon source. The B8 bacteria in relation to the others, was the most reduced the amount of DPCIP. The results suggest that microorganisms are tolerant and have a high potential for glyphosate degradation and can be used in future studies of bioremediation of soils contaminated with this pesticide.
| Identifer | oai:union.ndltd.org:IBICT/oai:localhost:prefix/189 |
| Date | 07 March 2016 |
| Creators | Demichelli, Fernanda Natal? |
| Contributors | Cazarolli, Luisa Helena, Passos, C?tia Tavares dos |
| Publisher | Universidade Federal da Fronteira Sul, P?s-Gradua??o em Agroecologia e Desenvolvimento Rural Sustent?vel, UFFS, Brasil, Campus Laranjeiras do Sul |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | Portuguese |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Source | reponame:Repositório Institucional da UFFS, instname:UFFS, instacron:UFFS |
| Rights | info:eu-repo/semantics/openAccess |
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