Solid-phase amination of Geotrichum candidum lipase: ionic immobilization, stabilization and fish oil hydrolysis for the production of Omega-3 polyunsaturated fatty acids

Abstract

In this paper, solid-phase chemical amination was applied to enrich the surface of Geotrichum candidum lipase (GCL) with amino groups. The aminated enzyme was slightly thermostabilized and showed a different activity profile at different pH in relation to the non-aminated enzyme. Furthermore, the chemical modification allowed the enzyme to be rapid and easily immobilized on carboxymethyl and sulfopropyl agarose-based supports. The cationically exchanged derivatives presented higher thermostability and higher stability at alkaline pH than the soluble aminated enzyme. In addition, the carboxymethyl derivative was 5.4-, 8.7- and 9.1- and the sulfopropyl derivative was 6.6-, 11.7- and 10.7-fold more stable than the free aminated enzyme in methanol, propanol and cyclohexane, respectively. The ionic derivatives were applied for fish oil hydrolysis in organic aqueous medium at 37 °C. After 72 h of reaction, Omega-3 production corresponded to 354 and 482 μM using the carboxymethyl and sulfopropyl derivatives, respectively. These derivatives resulted, respectively, in 2.4- and 3.2-fold increased fish oil hydrolysis when compared to the soluble aminated lipase. After the reaction, carboxymethyl derivative presented 6.65 U per gram of support and sulfopropyl derivative showed 7.85 U per gram of support, making them attractive for industrial application.