(693e) Engineering a Novel Omega-3 Fatty Acid Biosynthesis Pathway in Yarrowia Lipolytica

Omega-3 long chain fatty acids are essential for human health and development. The stagnant production of omega-3 fatty acids from fish oils no longer meet the demands of the fast growing aquaculture and nutraceutical market. A sustainable and economic source of omega-3 fatty acids is urgently needed. Here we report a systematic approach to metabolic engineering non-conventional yeast Y. lipolytica for eicosapentaenoic acid (EPA) production from non-sugar substrates such as cheap plant oils and rendered animal fats. We first established an alternative EPA biosynthesis pathway into Y. lipolytica by heterologous expression of a set of elongases and desaturases utilizing acyl-CoA instead of phospholipids, resulting in a high level of EPA production, while avoiding accumulation of undesired intermediate fatty acids. We also enhanced the assimilation and synthesis pathways of triacylglycerides, and disrupted its degradation pathway to improve the efficiency of utilizing exogenous lipids as building block for EPA production. By redirecting carbon flux towards fatty acid elongation and desaturation, we further increased the amount of EPA that was incorporated into triacylglycerol. Additional strategies to increase acyl-CoA flux will be discussed. Our results illustrate that the acyl-CoA pathway circumvents bottlenecks in the conventional phosphatidylcholine dependent desaturase pathways.