Imobilização por encapsulação de lipase de Aspergillus niger em matriz sol-gel obtida a partir de farinha de sementes de abóbora

Abstract

The use of lipases as biocatalysts for chemical reactions typical of the industry is growing every day. These enzymes are capable of acting on ester bonds present in acylglycerols and may be produced by fermentation, through the use of agro-industrial waste. However, enzymes in free form cannot be reused which economical view point, make its application with high financial investment. One of the strategies used for industrial applications is the immobilization of enzymes using various methods, high lighting the sol-gel technique for the preparation of biocatalysts, to be quite promising. Therefore, the aim of this study was the immobilization process for encapsulation of lipase of A. niger, this enzyme, obtained by fermentation of flour, pumpkin seeds, immobilized in hydrophobic matrices obtained from the sol-gel technique, perform biochemical, morphological and physico-chemical free and immobilized lipase. The immobilized lipase had a yield of immobilization (71.4%). The free enzyme showed higher hydrolytic activity at pH 4.0 and temperature of 37ºC and immobilized at pH 3.0 and temperature of 45ºC. Lipase both free and immobilized showed greater stability at pH 6.0, however, the immobilized lipase showed higher thermal stability at 45ºC, and the half-life of 13.6 h (45ºC) and 7.0 h for the free lipase 37°C for 240 min of incubation. The highest value of Km of the immobilized enzyme (57.05 mM) compared to the free enzyme (45.38 mM) indicating a lower affinity of enzyme towards the substrate due to immobilization process. The operational stability of the immobilized lipase was maintained with 50% of its activity after six cycles of reuse. In the morphological and physicochemical was possible to verify the structure of higher porosity biocatalyst immobilized and according to the pore diameter was observed that the support and the immobilized biocatalyst are characterized as mesoporous solids. The process of immobilization conferred greater resistance to thermal lipase immobilized on the free, observed by the sharp mass loss that occurred with the free lipase, losing almost all its mass (99%) in thermal analysis by thermogravimetry.