Comparación de la cinética de decoloración de índigo carmín utilizando diferentes sistemas de inmovilización de enzimas extracelulares de Trametes versicolor

Abstract

In this work was evaluated the kinetics of discoloration of the indigo carmine dye using extracellular enzymes of Trametes versicolor immobilized on different supports. It was tried different culture media for the growth of Trametes versicolor, the best culture medium was the 12 (concentration of protein 2.54 mg/L, Lac specific activity of 12.89 kU/mg protein and Per specific activity of 5.48 kU/mg protein), it was concentrated by ultrafiltration with a membrane of 1 kDa. Ligninolytic enzymes present in the enzyme concentrate were immobilized on 5 different systems: 1 (Silica commercial amorphous, covalent bonding), 2 (Silica from TEOS, covalent bonding), 3 (Silica from TEOS, thiols via covalent bonding), 4 (chitosan, crosslinking) and 5 (alginate, chitosan, encapsulation). The discoloration of IC (100 ppm) with the systems 1A, 1B, 1C, 2, 3, 4, 5 and the free enzyme was carried out at 7, 24, 6.3, 84, 97, 6.7, 34 and 5.7 h respectively; also were quantified the cycles of use of biocatalysts, being the 1C system which had more (45 cycles in 4 months). Also examined the biochemical properties of the set of enzymes present in the Tv.’s enzyme concentrate like the effect of pH and temperature, in the systems 1A and 1C was an increase in the pH range in which the discoloration carried out from 2-12, all systems tested were less susceptible to temperature changes than pH changes, the system 1A showed higher thermal stability. Immobilization systems affected the affinity of the substrate to the active site, resulting KG values higher than for the EC, but it was retained sufficient affinity to be carried out the discoloration. Discoloration products of indigo carmine with the immobilized enzymes were not phytotoxic, these systems could be used to remove indigo carmine from the industrial textiles effluents and take advantage of the waste water. The most promising system was the system 1C, it retained the highest amount of laccase activity, decolorized in a pH range of 2-12, increased optimum temperature and increased the range of temperature (50 - 80 °C), degrading IC accounting 45 cycles of use in 4 months; remained 98.2% of its Lac specific activity after 16 weeks of storage at 4 ° C. This system decolorized up to 1600 ppm of IC in 5 days.