Laccase from Trametes versicolor supported onto mesoporous Al2O3: Stability tests and evaluations of catalytic activity

Mesoporous Al2O3 obtained via a soft template method was used as a support for the immobilization of laccase from Trametes versicolor. Porous alumina is a very attractive engineering material extensively used in catalysis, adsorption and separation. The proposed route of synthesis of Al2O3 yielded a material with high well developed parameters of the porous structure and thermal, and kinetic stability. The next stage involved typical adsorption immobilization of laccase at different pH (3-6). The support and prepared biocatalytic system were comprehensively analyzed with respect to morphology, porosity, electrokinetic and thermal stability, and characteristic functional groups. Furthermore, the oxidation reaction of sulfonic acid was used as a model reaction to evaluate the catalytic activity of obtained biocatalyst. Based on this reaction, the influence of pH and temperature on catalytic activity was determined, in addition to the system's storage stability and reusability. The biocatalytic system exhibits catalytic activity from 40% up to 100% in the analyzed pH range 3-6 and in the temperature range 30-70 degrees C. Additionally, laccase immobilized onto Al2O3 retains approximately 65% of its initial activity after 30 days of storage, and around 60% after 10 reaction cycles. A suggested mechanism of laccase immobilization was also proposed.