(211a) Production of Omega-3 Fatty Acids by Fermentation of Metabolically Engineered Yarrowia Lipolytica

The omega-3 fatty acids, cis-5, 8,11,14,17-eicosapentaenoic acid (C20:5; EPA) and cis-4,7,10,13,16,19-docosahexaenoic acid (C22:6; DHA), have been shown to confer wide-ranging health benefits against e.g., cardiovascular disease, rheumatoid arthritis, Alzheimers disease, lung fibrosis and inflammatory bowel disease.  Currently, the major sources for omega-3 fatty acids are fish oil, microalgae, and a limited number of species of plants. Due to high costs, uncertain availability, and many other disadvantages within the current sources, DuPont has developed a clean and sustainable alternative source of omega-3 fatty acids through fermentation using a metabolically engineered strain of Yarrowia lipolytica. Specifically, desaturase and elongase genes have been introduced into the oleaginous yeast to utilize certain carbon sources to synthesize omega-3 fatty acids under fermentation conditions. This metabolic engineering of Yarrowia also provides a platform technology to produce the tailored omega-3 (EPA, DHA) or omega-6 fatty acids (ARA, GLA) in the oil. The strain candidates were evaluated via culture tubes, shake flasks, micro-24 bioreactor, and lab-scale fermentation experiments. The typical fermentation process consists of a nitrogen-rich growth phase and a nitrogen-starved oleaginous phase. Medium components and process conditions were optimized to improve the omega-3 fatty acid production. Mathematical modeling was a useful tool to analyze, optimize, control, and scale up the fermentation process. The yeast triacylglyceride oil produced has a unique fatty acid profile with greater than 55% as EPA (corresponding to the highest omega-3 fatty acid reported so far in the oil), and less than 8% as saturated fatty acid. The developed fermentation process was successfully scaled up to commercial scale. The produced EPA oil (Newharvest ^TM) has been used as human nutritional supplement; and the EPA-rich biomass has been used as salmon feed to raise brand salmon, Verlasso^TM (www.verlasso.com).