A promising alternate lipase for biodiesel fuel production

Abstract

By screening samples from different sources, a high-yield yet low-cost lipase of Enterobacter aerogenes was found and used in biodiesel production. The enzyme activity of Enterobacter aerogenes reached 34.16 U·mL^−1 under the optimum conditions of initial pH 9.0, agitating at 30°C for 40 h, using NaHCO₃ and glucose as carbon sources and peptone as nitrogen source, with 0.1% (w/v) MgSO₄·7H₂O. When adding 1.0% (w/v) olive oil to the culture, the enzyme activity reached 66.31 U·mL^−1, which increased by 56.5% compared to that obtained by using 2.0% (w/v) olive oil as the sole carbon source. The lipase of Enterobacter aerogenes was immobilized by diatomite and used to catalyze biodiesel with rapeseed oil as raw materials, the transesterification rate was 92.91% under the optimum reaction conditions, which were using 1000 U immobilized lipase and 5 mL n-hexane, with ethanol as acyl acceptors, at the molar ratio of oil/ethanol of 1∶4, and adding ethanol twice, at 35°C for 48h. Therefore, the Enterobacter aerogenes will potentially serve as a promising alternative lipase for biodiesel production.

Keywords

Enterobacter aerogenes / enzyme activity / biodiesel / transesterification rate