Omega3多不饱和脂肪酸（Polyunsaturated fatty acids, PUFAs）在生物细胞中发挥重要作用。目前二十二碳六烯酸（Docohexanoic acid, DHA）已实现大规模微生物生产和市场化，然而微生物来源二十碳五烯酸（Eicosapentaenoic acid, EPA）短缺仍是该产品商业化限制因素。本项目通过解析裂殖壶菌Schizochytrium ATCC1381和希瓦氏菌Shewanella MR-1聚酮合成酶（Polyketide synthase，PKS）基因簇结构，比对分析定位关键差异基因，确定Schizochytrium ATCC1381利用PKS途径合成EPA/DHA的关键控制基因位点，进而定向重组构建EPA合成工程菌株，阐明裂殖壶菌PKS途径合成多不饱和脂肪酸的代谢与调控机制，揭示链长基因KS-CLF在裂殖壶菌合成EPA过程中的功能。

Omega3-long-chain polyunsaturated fatty acids are important components of the human diet supplements because of their contribution to several aspects of health, including the development of the infant brain, the function of the eye, the synthesis of hormones and signaling molecules, and the prevention of cardiovascular diseases. Microbial docosahexaenoic acid (DHA) has been widely industrialized. However, EPA from microorganism is still a long way to commercial production. In this research, the gene clusters of polyketide synthase pathway (PKS) from both Schizochytrium ATCC1381 and Shewanella MR-1 were analyzed and then compared to get the key differential genes regarding PUFAs production. The key genes encoding EPA/DHA synthesis were then determined in Schizochytrium sp. Furthermore, an engineered Schizochytrium was constructed to overproduce EPA. The metabolic and regulation mechanisms of the PKS pathway for PUFAs synthesis were finally revealled including the role of ketosynthase-chain length factor (KS-CLF) during EPA synthesis in Schizochytrium.