Potencial do fungo Trametes lactinea nos processos de descoloração e degradação enzimática do corante têxtil índigo carmim

Abstract

The textile industry generates highly concentrated effluents, containing a lot of synthetic dyes residues applied in the dyeing and washing processes. The textile dyes are toxic compounds, so the effluent discharged in water bodies cause serious damage to the environment and risks to the human health. Most effluent treatment methods do not promote the complete degradation of these dyes, and for that reason, there is a demand for the development of new strategies. One of the strategies is bioremediation, which consists of the use of microorganisms that can degrade contaminants from the effluent. Many species of fungi have this ability, therefore showing potential to be used as a sustainable alternative for the treatment of colored wastewater. This research aims to evaluate the potential of the fungus Trametes lactinea on the decolorization of the textile dye indigo carmine, which is used to dye denim and is difficult to degrade. This species produces laccases, oxidases that are capable of degrading complex organic matter and have the potential to degrade dye molecules. The first decolorization test, carried out in liquid medium containing indigo carmine dye and fungal inoculum, revealed 47% decolorization after 120 hours. In order to optimize the decolorization by enzymatic degradation, factorial design and central composite design studies were conducted to determine optimal conditions for laccase activity produced by T. lactinea. As a result of these studies and the statistical analysis, the addition of 0.4 mg of tannic acid to the medium and 120 hours of incubation were found to be the best conditions. Therefore, the fungus was cultured under these conditions to produce an optimum enzyme mixture to be used in the decolorization of indigo carmine dye, carried out in Erlenmeyer flasks containing 50 mL of the dye solution plus 5 mL of the enzyme mixture. 87.5 U/mL was the maximum laccase activity measured and it was observed 100% decolorization rate after 15 days. FTIR and UV-Vis spectroscopies highlighted differences between the spectra of the control samples and treated samples. The findings indicate that Trametes lactinea enzymes can degrade indigo carmine and that laccase probably plays a role in the biodegrading process