Síntese de agregados reticulados para a lipase produzida de Geotrichum candidum.

Abstract

Lipases (triacylglycerol acylhydrolases; E.C.3.1.1.) are enzymes responsible for the hydrolysis of oils and fats, and can be obtained by microorganisms. They have application in several industrial sectors, since they have the characteristics of being renewable, biodegradable, selective, and specific. However, lipases also have some limitations that need to be overcome, and so enzyme immobilization is a good alternative to minimize these limitations. Among the several types of enzyme immobilization, the cross-linked enzyme aggregates (CLEAs) stand out. The CLEAs are obtained from the lipase precipitation by a precipitating agent and then are cross- linked using a cross-linking agent such as glutaraldehyde. Geotrichum candidum (G. candidum) is a producer of lipases, which have the property of hydrolyzing the ester bonds present in long-chain fatty acids with double bonds in cis-position at carbon 9. In this context, this work aimed to evaluate some fundamental parameters for the formation of CLEAs such as the choice of precipitating agent, the concentration of glutaraldehyde, (5, 10, 20 and 30 mol of aldehyde groups/mg of protein), the proportion of additive used in relation to the amount of lipase present in the enzymatic extract (1:1; 1:2; 1:3;1:7 and 1:10 m/m), and additives used were bovine serum albumin (BSA), polyethyleneimine (PEI) and soy protein (PSH), the percentage of the surfactant sodium dodecyl sulfate (SDS) (0.10 , 0.50, 1.00, 1.50 and 2.00 % m/v), the crosslinking-time (60, 120 and 240 min) and the pH for the enzymatic extract (6.0 and 7.0 ). The best results for the precipitating agent were for acetone obtaining a recovered activity of 46.82  1.21 %. The CLEAs with the best global activity value (about 18%) and the lowest lipase leaching in the washing steps were obtained using PEI as an additive (PEI-CLEAs). The conditions used were 20 mol of aldehyde groups/ mg of protein, ratio of 1:7 (m/m) of lipase per additive, crosslinking time of 120 min and pH 6.0 in the enzymatic extract. The study of surfactant in the preparation of CLEAs showed that the use of SDS did not increase the global yield for CLEAs formed with the additives BSA, PEI and PSH.