Imobilização das lipases de Burkhoderia cepacia em suporte de quitosana funcionalizada com edta e aplicação na reação de esterificação de ácidos graxos

Abstract

Biocatalysis uses enzymes in purified form or whole cells to synthesize reactions. However, the cost of using the free enzyme is still high and the integral cell has limitations regarding the reaction medium, such as pH variations, and high temperatures, among others. Enzyme immobilization is an alternative, which has been shown to be effective. The purpose of immobilizing an enzyme is to obtain a biocatalyst with activity and stability that remains intact during the process, compared to the enzyme in its free form. It can even achieve a catalytic activity superior to that of free enzymes. The immobilization of lipase from Burkholderia cepacia was carried out in supports of chitosan functionalized with EDTA (Qui-EDTA) and chitosan-EDTA activated with glutaraldehyde (Qui-EDTA-Glu), in order to bind the enzyme to the support, from covalent bonds between the amino groups of the enzyme and the aldehyde groups of glutaraldehyde or to the acid groups of EDTA. The enzymatic activities of the derivatives in the p-nitropalmitate hydrolysis reaction were determined from the p-nitrophenol concentration formed. In this way, activities of 336U/g were obtained for the chitosan derivative functionalized with EDTA and 212U/g for the chitosan derivative activated with glutaraldehyde. The operational stability analysis showed that there is a 34% decay in the recycling of the chitosan-EDTA derivative activated with glutaraldeide, however the derivative activated only with EDTA remained stable between cycles. The bifunctionalized chitosan derivative showed better storage stability than the functionalized support with only EDTA. The derivatives were also tested against the esterification reaction, where the support Qui-EDTA was better conversions, of 80% in the first use. Thus, the efficiency of the biocatalyst obtained from the chitosan functionalized supports is remarkable.