Bactérias com Potencial Biotecnológico na Descoloração de Corantes Têxteis

Abstract

The discharge of effluents from textile industries for water bodies is currently a major concern for environmentalists as a function of synthetic dyes used to color fabrics thus polluting the environment. Biological treatments, especially with the use of bacteria, present themselves as the most economically viable and widely used to decolorize colored effluents. Thus, studies were conducted to test the color removal of dyes Remazol Brilliant Blue R, Orange G and Orange II using isolated and in mixed culture strains of Escherichia coli and Aeromonas hydrophila. Firstly, the isolation of bacterial strains from three different environments was made. Then, tests were performed to verify that the dye concentration would limit the growth of each microorganism. In addition to tests of decolorization, other parameters such as pH, biomass, COD removal, total protein and toxicity of metabolites were also monitored. The Escherichia coli strain isolated from the marine environment was able to decolorize concentrations of 2, 5 and 2 mg L-1, respectively, for the RBBR dye, Orange G and Orange II dyes, while the strain E. coli isolated from textile effluent, decolorized in concentrations of 5, 0.5 and 5 mg L-1, respectively. The bacteria Aeromonas hydrophila decolorized, respectively, at 10, 5 and 5 mg L-1, while the consortium of three bacteria decolorized at concentration of 5 mg L-1 for the three dyes tested individually. In these culture conditions the decrease in the rate of COD ranged from 45% to 69% with the lowest rate observed in the assay containing A. hydrophila and dye Orange II (45%) and the highest removal rate in the test containing the dye RBBR and the consortium (69%). Bioassays using Artemia salina showed that during the process of decolorization metabolites were produced with recalcitrant characteristics. The results show that the bacteria Escherichia coli and Aeromonas hydrophila have biotechnological potential in textile dyes, provided that they use low dye concentrations decolorizing