Seleção de microrganismos endofíticos com potencialidades para a biorremediação de ambientes contaminados com hidrocarbonetos de petróleo e/ou derivados
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2009-03-16
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Universidade Federal de Goiás
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Endophytic microorganisms live inside plants showing no apparently damage for the host, often assisting in survival of plants, helping its growth with production of phytohormones, phosphates solubilization, nitrogen fixation and enzymes production, or they can metabolize organic contaminants, like petroleum and derivates. This work aimed to isolated and identified endophytic microorganisms of plants present in impacted areas, as well as test their ability in petroleum and its derivatives degradation, identify bacteriocin production, to test their nitrogen fixation capability, phosphate solubilization, indol-acetic acid (IAA) and enzymes production. Plant samples were collected, in an area impacted with asphaltic and mud, were superficially disinfected using 70% ethanol, sodium hypochlorite and sterile distilled water. After macerated and fragmented, the samples were incubated at 30°C for about 72 hours, when growth of microorganisms was observed in culture media: Nutrient Agar, TSA (Tryptone Soya Agar) and King medium. The verification of petroleum and derivatives degradation capacity was performed in ELISA plates, exposing the bacteria to a solution of Minimal Medium, the dye DCPIP solution (2,6-dicloroindofenol sodium salt) and petroleum or derivative tested (burning oil, lubricating oil, diesel oil and gasoline). A positive reading for degradation was observed by discoloration of DCPIP. Among nine bacteria tested, three showed degradative activity in different fractions of petroleum, diesel oil and gasoline, and others showed different profiles. This result shows the potential of these microorganisms for application in bioremediation processes. The production of IAA was tested on TSA medium supplemented with tryptophan and only one sample was positive, while none was considered phosphate solubilizing. Testing the nitrogen fixing, samples were inoculated for a free nitrogen culture media, showing growth after 24 hours of incubation (positive results), however it s isolated did not show positive results in the acetylene reduction test, which confirms activity of the enzyme nitrogenase. The samples showed different profiles for the production and activity of bacteriocins against the clinical isolates tested. There were no detected activity of endoglucanase, cellulolytic and pectinolytic enzymes, but esterases, ß-glucosidases, proteases and amylases were positive. Some isolates were identified from the sequencing of 16S DNA, whose sequence was compared to database (GenBank), and then diagnosed as Bacillus cereus, Staphylococcus pasteuri and Pseudomonas sp. The endophytic bacteria isolated from Cerrado plants confirmed their potential for use in bioremediation, plant growth promotion and diverse enzyme production, with potential for use in pharmaceutical, food, textiles, among others.
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OLIVEIRA, Natalia Carvalhaes de. Selection of endophytic microorganisms for biorremediation in impacted soils with petroleum hydrocarbons and derivates. 2009. 96 f. Dissertação (Mestrado em Medicina) - Universidade Federal de Goiás, Goiânia, 2009.