Production of High-Value Polyunsaturated Fatty Acids Using Microbial Cultures

Microbes can produce not only commodity fatty acids, such as palmitic acid (16:0) and stearic acid (18:0), but also high-value fatty acids (essential fatty acids). Most high value fatty acids belong to long chain polyunsaturated fatty acids (PUFA), such as omega-3 fatty acids (e.g., eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)) and omega-6 fatty acids (e.g., arachidonic acid (ARA) and γ-linolenic acid (GLA)). EPA (20:5n-3) is a 20-carbon fatty acid with five double bonds, and the first double bond is in the n-3 position. DHA (22:6n-3) is a 22-carbon fatty acid with 6 double bonds and the first double bond is also in the n-3 position. Both EPA and DHA play an essential role in cardiovascular health including prevention of atherosclerotic disease development (Zehr and Walker, Prostaglandins Other Lipid Mediat 134:131-140, 2018). ARA (20:4n-6) is a 20-carbon fatty acid with four double bonds, and the first double bond is in the n-6 position. GLA (18:3n-6) is an 18-carbon fatty acid with three double bonds, and the first double bond is in the n-6 position. ARA and GLA have multiple biological effects, such as lowering blood cholesterol, and lowering cardiovascular mortality (Poli and Visioli, Eur J Lipid Sci Technol 117(11):1847-1852, 2015). This chapter provides details on microbial production of EAP, DHA, ARA, and GLA.