Magnetic Cross-Linked Enzyme Aggregates of Aspergillus oryzae ST11 Lipase Using Polyacrylonitrile Coated Magnetic Nanoparticles for Biodiesel Production

The biodiesel production by enzymatic catalysis is the environmentally friendly production process. In this work, the polyacrylonitrile coated magnetic nanoparticles were prepared and used as a core supporter for producing magnetic cross-linked enzyme aggregates (mCLEAs) from Aspergillus oryzae ST11 lipase with the co-feeding of bovine serum albumin (BSA). The highest immobilized lipase activity was 0.09 U/mg-support or 81.7% of recovered activity. The resulting mCLEAs exhibited the desired characteristics; it had improved the stabilities for pH, temperature, as well as storage comparing to free enzyme. Moreover, when this biocatalyst was used for biodiesel production at the optimal conditions (30% w/w of mCLEAs, 30% w/w of water content and stepwise addition of methanol), the biodiesel conversion was 95% within 24 h of reaction, while one-step addition of methanol produced 81% conversion. The mCLEAs could be reused for 5 cycles and retained the biodiesel conversion higher than 60%.