ChEMS Department Seminar: Sustainable Omega-3 Production by 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. Fermentation research has been focused on strain evaluation, process optimization, and scale-up to achieve a successful commercial production. The strain candidates were evaluated via culture tube, shake flask, micro-24 bioreactor, and lab-scale fermentation experiments. Medium components and process conditions were optimized to improve the omega-3 fatty acid production. Mathematical modeling was used 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 for commercial production. 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, VerlassoTM (www.verlasso.com).