Avaliação qualitativa da capacidade de biodegradação do tolueno por bactérias isoladas

Abstract

Contamination of surface water by polluting compounds can cause various environmental damages due to interference in the ecosystem, affecting local biodiversity, the quality of rivers and lakes, in addition to being harmful to human health. Toluene is a commercially important toxic compound, commonly used as a diluting agent and solvent, which can be present in pesticide formulations. In areas destined for agriculture, the use of pesticides can contaminate not only the soil, but also rivers and lakes, through surface runoff. This work sought to isolate bacterial strains and select, among these, bacteria with the ability to biodegrade toluene and potential for use in bioremediation processes. The strains were obtained from two samples of water from a lake that is subject to contamination due to its proximity to a large area intended for agricultural cultivation. 4 strains of bacteria were isolated for the tests and the biodegradability was verified using the colorimetry method by analyzing the color of the redox indicator 2,6-dichlorophenol indophenol, which has a blue color when oxidized and is colorless when reduced. This color change indicates the enzymatic activity of the bacteria and thus biodegradability. To analyze this color change, photographs of the tests were taken and, with the images obtained, a discoloration scale was created, determining qualitative indicators. Subsequently, slides were prepared with each of the strains using the Gram staining method to observe the morphology under the microscope. From the analysis of the images obtained, it was observed that the synergistic tests of bacteria 3 with bacteria 4 showed potential for biodegradation of toluene. Thus, the synergism of these microorganisms potentiated the biodegradation effect of the compound. This indicates that these strains may be promising for bioremediation of contaminated sites.