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%.
Keywords: Aspergillus oryzae; Biodiesel; CLEAs; Lipase; Magnetic nanoparticle.