Imobilização de lipases em tecido de algodão: aproveitamento de resíduos têxteis para obtenção de biocatalisadores heterogêneos

Abstract

Pieces made from cotton decompose in twenty years and can be used in enzymatic immobilization as an eco-friendly support, reducing production costs and giving them better disposal. Therefore, the main objective of this present work was to immobilize lipases from Penicillium corylophilum IOC 4211 on cotton fabrics for subsequent biocatalytic application. To this end, the simultaneous production and immobilization of lipases by solid state fermentation was studied. In this step, sunflower seed bran was used as substrate, 1 g of cotton fabric, medium humidity of 55%, 29°C, 144 h. The tissue before and after the fermentation and immobilization process was analyzed by Fourier transform infrared spectroscopy (FTIR) coupled to the attenuated total reflectance (ATR) accessory and thermogravimetric analysis (TGA). In relation to FTIR, only a broadening of the absorption band was observed in the range 3600-3000 cm-1, which corresponds to the region of peptide bonds between hydroxyl groups (-OH) and amines (-NH2) of the lipase. For ATG, a small decrease in tissue thermal stability was observed after immobilization. The lipolytic activity for the immobilized lipase (Lip-Tissue) was 41.1 ± 2.5 U g-1. The effect of temperature (40 to 60°) and stability at temperature (40 to 70°C) and in organic solvents on the activity of immobilized lipase were also evaluated. The results showed that the activity was higher (105.33 ± 7.0 U g-1) at 55°C, the Lip-Tissue lost approximately 40% of its initial activity after incubation at 70°C for 30 min and was more stable in isoamyl alcohol (138 ± 16% residual activity). Lip-Tecido was applied in the synthesis of ethyl oleate, using n-heptane as the solvent, in an experimental design 23 (temperature-T, enzymatic units-U and molar ratio acid: alcohol-MR), with triplicate at the central point. The highest conversion to ester in 24 h was 56% (44°C; 50 U and RM of 1:1). It was possible to conclude that the immobilization method performed is simple, versatile and economical to prepare a heterogeneous biocatalyst with catalytic efficiency in hydrolysis reactions and ester synthesis. Furthermore, there is the possibility of other types of fabrics being used as support in immobilization aiming at the use and valorization of textile waste.