Lipase de Aspergillus niger obtida a partir da fermentação de resíduo de mangaba: potencial de imobilização em matriz sol-gel

Abstract

The lipolytic enzymes are the most important group of enzymes with enormous potential for technological applications in nowadays, these are part of a group of enzymes that are associated with the metabolism and hydrolysis of lipids and has one of most influential economies in terms of sales, after proteases and amylases. The aim of this work was to obtain lipase from Aspergillus niger from state solid fermentation of mangaba residue and subsequent immobilization by different techniques in sol-gel matrix. The maximum production of enzyme (62.46 U/g) was obtained at temperature of 30ºC in 120h of fermentation. The immobilized lipase by covalent bonding showed immobilization yield of 91.62 %. The free and immobilized lipases were characterized: being the optimal pH of 5.0 and 3.0, higher stability at pH 7.0 and 2.0, respectively; the optimum temperature for both enzymes was of 55°C, being the higher stability at 50°C and 55°C, respectively. The half-life time of immobilized lipase was of 63.01 h. The immobilized enzyme showed a lower maximum rate of reaction (Vmax = 714.29 U/mg) and higher Michaelis-Menten constant (Km = 115.29 mmol) than those obtained for the free enzyme (Vmax = 1250.0 U/mg and Km = 77.0 mmol), which showed a lower affinity for the substrate. The higher operational stability was obtained for the immobilized enzyme by covalent bonding being the relative activity above 50% until 6 cycles of reuse. The lipase from Aspergillus niger obtained from the fermentation of mangaba residue and immobilized in sol-gel matrix by covalent binding demonstrated potential for future applications as biocatalysts in reactions of industrial interest.