Avaliação do potencial biotecnológico de isolados hidrocarbonoclásticos provenientes de postos de combustíveis automotores

Abstract

Gas stations are responsible for important impacts due to the present petroderivatives exerting selective pressures, leading to changes in metabolism and physiology of various soil microbial groups. Bacteria and fungi use similar metabolic pathways during the elimination of hydrocarbons in the environment. Although microbial concentration in areas with a long history of contamination is temporarily reduced and prevented from promoting effective elimination of hydrocarbons, proportionally hydrocarbonoclastic individuals are more numerous. Knowing their metabolic potential makes it possible to employ them in interventions that focus on the biological removal of petroleum products. In this context, the objective of this work was to isolate and identify microorganisms from soil and fuel samples obtained from 7 gas stations in Greater João Pessoa, knowing its potential as a bioremediation agent through rapid and reproducible assays. A total of 17 strains were obtained: 8 gram negative bacteria and 9 ascomycetes. From the total of isolates, 4 bacteria and 4 filamentous fungi were submitted to the hydrocarbon use test in microdilution systems containing mineral medium and indicator 2,6-dichlorophenl indophenol (DCPIP). The collapse of the oil drop occurred between 48 and 96h. Then fractions containing cells at the beginning of the stationary phase or excreted products of their metabolism were mixed with diesel oil and fuel oil in a 3: 2 ratio to determine the emulsification index. The bacteria obtained an index of approximately 40% within 72h, and for the fungi the maximum index was about 50% within 48h, but the bacteria produced a more stable emulsion at room temperature. Under the experimental conditions employed, 3 bacteria (Aeromonas hydrophila TP17, Burkholderia cepacia TP21 and Citrobacter freundii TP20) and 2 Aspergillus sp (TP11 and TP12) were considered the microorganisms with the highest application potential as bioremediation agent.