Imobilização da lipase de Candida Antarctica do tipo B usando como suporte fibra de coco verde pré-tratada por explosão a vapor

Abstract

The present study aims to immobilize the enzyme CalB (Candida antarctica lipase B) in coconut fiber as a support. Two distinct systems were considered in order to obtain an immobilization composed, for the most part, of covalent bonds. In the first system, coconut fiber biomass was silanized with APTES (3-aminopropyltriethoxysilane), then activated with glutaraldehyde and an enzyme was immobilized. In the second system, the biomass was also silanized with APTES, an enzyme was immobilized and subsequently coated with glutaraldehyde. After immobilization, the parameters of the immobilized enzyme were controlled to evaluate the efficiency of CalB immobilization in the coconut fiber matrix. Subsequently, thermal stability tests were carried out, which consisted of exposing the immobilized enzyme to high temperatures (60ºC, pH 7.0). Finally, the desorption test was performed, which aimed to evaluate the type of bonds/interactions present in the immobilization. Desorption was performed using NaCl (1M) and Triton X-100 (1.0% (v/v)) solutions in order to investigate whether the rejected forms were predominantly ionic or hydrophobic. The results showed that the CalB enzyme was immobilized in both systems, with immobilization yields of around 43.4 and 50.4% in 24 h of contact in the Biomassa-APTES GA-CalB and Biomassa-APTES-CalB systems, respectively. For both systems, the activities of the immobilized enzymes remained similar, around 9.5 and 9.2 U/g. Furthermore, the inactivation profiles of the immobilized enzymes showed a similar behavior, with an average relative activity of around 65.0% at 90 min of inactivation for both systems. Coating with glutaraldehyde after the immobilization process (Biomassa-APTES-CalB-GA biocatalyst) achieved greater retention of enzymatic activity after transfer with NaCl (Relative activity: 55.2%) and Triton X-100 (Relative activity: 82 .3%). This evidences the formation of Schiff bases between enzyme-support, due to the high relative activity of the enzyme after both desorption processes. Thus, with the immobilization processes, active and stable biocatalysts were produced, mainly in the case of the second system, with potential application in actions of industrial interest.