(536e) Biomanufacturing of Omega-3 Eicosapentaenoic Acid from Waste Cooking Oil By Metabolic Engineered Yeast Yarrowia Lipolytica

Omega-3 fatty acids, especially the eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have attracted scientific attention because they have been associated with a wide range of significant health benefits. Currently, the principal source of DHA and EPA is fish oils. Unfortunately, fish oils are not able to meet the increasing global demand because of overfishing and the environmental pollution of marine ecosystems. The development of synthetic biology enables the heterologous expression of omega-3 pathways in industrial-friendly microorganisms. Recently, the metabolically engineered yeast, Yarrowia lipolytica, has been used to commercially produce EPA in an industrial mass scale by the E.I. DuPont Company. As in most biomanufacturing processes, glucose was used as substrates for omega-3 fatty acids production. However, our research found that the plant oils or free fatty acids (FFAs) was more efficient than glucose to make omega-3 fatty acids. Y. lipolytica is often found in habitats containing lipids and has developed sophisticated mechanisms for efficient use of lipids, which provides us opportunities for biomanufacturing of high-value products from cost-effective agriculture feedstocks such as plant oils and their wastes. Here we present our most recent research results on how waste cooking oil (WCO) and FFAs were used to significantly improve the production of omega-3 fatty acids in the engineered Y. lipolytica. When the WCO was pretreated with lipase and then co-fed with glucose from 36 hr, an EPA titer of 7.8 g/L was obtained in fed-batch fermentation, which was nearly 50% higher than the fed-batch fermentation with glucose feeding only. However, it was also found that a significant portion of EPA was produced in the format of FFA when WCO was used as the carbon source for the omega-3 production. To convert the FFA of EPA into triacylglycerols and further increase the total EPA production, several key genes involved in lipid remodeling and fatty acid metabolism were investigated. To our best knowledge, this is the first research reporting a direct and efficient microbial conversion of a plant oil into a much more valuable omega-3 oil.