Produção de lacases por Aspergillus serratalhadensis URM 79/18 utilizando subprodutos agroindustriais

Abstract

Laccases are copper-containing ligninolytic enzymes and are known to be excellent oxidizing agents in the presence of oxygen. Among the ligninolytic enzymes, laccases are the most widely studied group, being known as green catalysts, as they promote the direct reduction of molecular oxygen to water without the formation of unwanted by-products. Currently, laccases are secreted mainly by fungi of the phyla Ascomycota and Basidiomycota and have a variety of industrial applications that include the discoloration and degradation of dyes and textile effluents, detergents for fabric bleaching, tooth whiteners for oral hygiene, pulp bleaching in the textile industry. fabrics and paper and in the deconstruction of lignocellulosic biomass. Therefore, the present study aimed at the production of laccases by solid state (FES) and submerged (FS) fermentation of Aspergillus serratalhadensis URM 79/18, a microorganism isolated from the Caatinga soil, using as substrates agro-industrial residues, wheat bran, soy flour, manioc and orange peel. The qualitative test performed by adding 3 Mm of ABTS substrate to PDA medium was positive for extracellular laccase production, confirmed by the formation of a green halo measuring about 34 mm. The orange peel substrate used in FES inhibited fungal growth up to 96 h of fermentation, and consequently there was no enzymatic production with this substrate. Laccase activity was determined using ABTS as substrate, so the highest enzyme activity was 305.56 U/mL obtained after 48h of FES at 30°C in wheat bran substrate, the second highest laccase production was 296 .29 U/mL also from FES, but in the manioc peel substrate and with a fermentation time of 72 hours. For the FS, the MS-2 medium modified by the use of ABTS as an inducer and also by the nutrient solution containing several metal ions was used, the substrates used were wheat bran and soybean flour in the fermentation time of 48 hours, being the highest activity of laccase in the FS obtained with the MS-2 medium modified by the nutrient solution and the addition of ABTS, being 0.1944 U/mL with wheat bran as substrate. Therefore, the recent fungal strain A. serratalhadensis is a laccase producer and has an ideal performance in solid-state fermentation, especially when the agro-industrial residue of wheat bran is used as a substrate, demonstrating its potential for the biotechnology industry.