米曲霉脂肪酶富集浓缩裂殖壶藻油脂中DHA的机理研究

本研究采用了米曲霉(Aspergillus oryzae, AO)脂肪酶水解法对裂殖壶藻油脂中的二十二碳六烯酸(Docosahexaenoic Acid, DHA)进行了浓缩。在AO脂肪酶最适反应条件下，水解12 h后，反应达到了平衡，产物中甘三酯含量降至40.2%，DHA含量升至55.43%，浓缩了1.58倍，回收率高达68.2%。通过气相色谱结合核磁共振碳谱(13C-NMR)对产物中甘油三酯脂肪酸组成及含量进行了分析，结果显示在酶解反应过程中，DHA倾向于留在甘三酯甘油骨架上，且sn-1,3位上的饱和脂肪酸易被水解而含量下降，表明AO脂肪酶水解反应对甘油骨架上的脂肪酸具有选择性，可将DHA富集在甘油三酯中。AO脂肪酶价格低廉，基于酶解反应的DHA富集工艺简单，深入了解反应的作用机制，将为后续的理论研究和实际应用提供依据。

Mechanical Study on Enriching DHA from Schizochytrium sp. Oil by Enzymatic Hydrolysis Catalyzed by Aspergillus oryzae Lipase

In this study, Aspergillus oryzae lipase (AO Lipase) was employed to hydrolyse Schizochytrium sp. oil aiming to achieve Docosahexaenoic Acid (DHA) enrichment. When the hydrolysis reaction reached equilibrium after 12 h, triglyceride separated from the hydrolysate was found to decrease to 40.2%, in which DHA content increased to 55.43%, with its recovery and concentration ratio as high as 68.2% and 1.58, respectively. Moreover, Gas Chromatography combined with 13C-NMR analysis for total fatty acids constitution of hydrolysate lipids revealed that DHA of large molecule is much harder to be hydrolysed away from glycerol skeleton during reaction, while most saturated fatty acids located in the sn-1,3 position could be easily broken away from glycerol skeleton. In conclusion, it was found that the specific hydrolysis selectivity over the variety of fatty acid linked to glycerol skeleton plays a crucial role in enriching DHA into the triglyceride of the enzymatic hydrolytes. Catalytic reaction mechanism of AO lipase -involved lipid hydrolysis explored in this study not only could offer theoretical foundation of DHA enrichment, but also would boost the formation of convenient and feasible techniques in combination of other follow-up procedures.