Activated magnetic lipase-inorganic hybrid nanoflowers: A highly active and recyclable nanobiocatalyst for biodiesel production

In this study, the surfactant activated lipase from Aspergillus oryzae was used to prepare magnetic hybrid nanoflowers by embedding Fe3O4 magnetic nanoparticles (MNPs) into hybrid nanoflowers (MhNF). Meanwhile, MNPs were integrated into the activated lipase hybrid nanoflowers through covalent cross-linking (cross-linked-MhNF). Activity recovery of the MhNF and cross-linked-MhNF was 190% and 174%, respectively. However, activity recovery of lipase hybrid nanoflowers (hNF) only retained 77%. Furthermore, the MhNF displayed higher Kcat/Km value than free lipase, indicating high catalytic efficiency of MhNF. Compared with free lipase, the MhNF exhibited high tolerance against methanol and storage stability. Furthermore, the MhNF could be easily recycled by magnet without obvious activity loss. After reusing for 10 cycles, the activated hNF only retained 26% activity of its original activity, while the MhNF still maintained 84% activity of its initial activity, indicating excellent reusability. In the reaction of producing biodiesel from soybean oil, the MhNF-catalyzed biodiesel yield reached 88%, while the free enzyme was only 69%. The yield of biodiesel catalyzed by MhNF was maintained at 76% even after 6 consecutive cycles.