Abstract: The lipases in the germinating seeds of oil crop have high specificity and efficiency to the substrate plant oil, the main sources in biodiesel production. The lipase activity during the different stages of rapeseed germination was determined, and accordingly, lipase was purified by salting out, ultrafiltration, and M-Bondapak-C18 column chromatography sequentially. The results showed that: 1) During the different stages of germinating seeds, the lipase activity in 6-day-old seedling was at the peak. Therefore, 6-day-old seedlings were chosen as the material for lipase extraction; 2) After salting-out, the specific activity of lipase was improved from 1.89 U/mg to 2.07 U/mg, with a recovery rate of 82.47%; 3) After ultra filtration with 10000 D membrane, the specific activity of lipase was improved to 2.46 U/mg, and the recovery rate was 75.84%; 4) The specific activity of further purified lipase by C₁₈ column chromatography was improved to 9.14 U/mg, with the recovery rate being 34.13%. The activity of final lipase prepared reached the level of commercial lipase.

Key words: rapeseed, lipase, purification, salting out, ultrafiltration, column chromatography