Biodegradação do corante vermelho congo por fungo basidiomiceto com proposta de tratamento de efluente contendo corante azoico

Abstract

The disposal of dyes without prior treatment of effluents causes changes in natural resources with high mutagenic and carcinogenic potential. Thus, the use of basidiomyces to remove these compounds from effluents containing dyes has been shown to be efficient in bioremediation treatments, due to the fact that they produce extracellular ligninolytic enzymes. The fungal isolate Lentinus crinitus CCIBT 2611 is recognized for its ability to degrade organic pollutants, so this study aimed to evaluate the degradation of the Congo Red dye (CI Direct Red 28) by the fungus Lentinus crinitus CCIBT 2611 by adding copper sulfate, a lacase enzyme mediator, and sucrose. The inoculum was performed in MEA medium (2%) at 30°C. For evaluation of discoloration, 100 mL of previously autoclaved 200 g.L-1 potato broth was used and distributed in Erlenmeyer bottles containing copper sulfate, dye and/or sucrose as determined by factor planning. The amount of 10 discs of MEA culture medium, containing the previously grown fungus, were added as inoculum. The culture was interrupted at 24 h, 48 h and 72 h by means of vacuum filtration using filter paper. The filtrate was used for the evaluation of lacase production, media discoloration by L. crinitus and pH measurement. The biomass retained in the filter paper was used to determine the dry mass. For the expansion of the degradation system, 1.4 L of sterilized potato broth was used in a wet way, as inoculum the immobilized fungus in sisal fiber was used, with addition of the concentration of 40 mg.L-1 of VC dye, 1 mM of CuSO4 and 2.5% of sucrose, which were determined in the first stage of the research, according to the best result of factor planning. The highest lacase production and dye discoloration suggested by factor planning was 7.5 U.L-1 of lacase production in assay 5, at 72 hours containing 20 mg.L-1 of dye and 5% of sucrose and 51.3% of discoloration in assay 9, at 48 hours of cultivation containing 40 mg.L-1 of dye, 1mM of CuSO4 and 2.5% of sucrose. In the expansion of the discoloration system, it was found that the results obtained showed that the addition of copper sulfate and sucrose to the degradation system favoured an increase in the tolerance of the fungus L. crinitus to higher concentrations of the dye.