Novel cold-adapted lipase from Psychrobacter sp. C18 immobilized on reduced graphene oxide-cellulose nanomatrix with high activity and stability

Abstract

Here, biocompatible hybrid graphene oxide-cellulose nanocrystals (rGO-CNC) were synthesized and used as nanomatrix to immobilize a novel recombinant cold-adopted lipase from Psychrobacter sp. C18. Different steps of the nanomatrix synthesis and the lipase immobilization were verified by FT-IR, DLS, SEM, circular dichroism, spectrofluorimetry, and spectrophotometer-based kinetic and thermodynamic studies. According to our results, the values of kcat for physically and covalently immobilized lipase were 1.06 and 2.47 times higher than that of the soluble lipase, respectively. Moreover, the remaining activity of lipases during storage stability at 4 °C for 30 days were estimated to be 2.47 and 1.25 more than that of the soluble lipase, respectively. In addition, covalently immobilized lipase was reused after 5 successive cycles while retained about 60 % of its initial activity. Although the physical adsorption strategy increased the catalytic efficiency by 2.45 times, compared with soluble lipase, the thermal stability of covalently immobilized lipase was 5.2 times higher than that of the soluble enzyme. Additionally, covalently immobilized lipase showed remarkable resistance against extreme changes in environmental conditions such as metal ions, organic solvents, and pH changes. Altogether, based on our results, the covalently immobilized novel cold-adopted lipase is a suitable candidate for biotechnological and industrial applications.