Production of 8,11,14,17‐cis‐eicosatetraenoic acid by Δ5 desaturase‐defective mutants of an arachidonic acid‐producing fungus, Mortierella alpina

Abstract Δ5 Desaturase‐defective mutants of an arachidonic acid‐producing fungus, Mortierella alpina 1S‐4, accumulate large amounts of 8,11,14,17‐ cis ‐eicosatetraenoic acid (20:4ω3) when grown with linseed oil. One of the mutants, the S14 strain, produced 1.65 mg of 20:4ω3 per mL of culture medium (corresponding to 66.0 mg/g dry mycelia and 11.6% of total cellular fatty acids) when grown in a medium containing 1% glucose, 1% yeast extract, and 4% linseed oil methyl ester at 28°C for 2 d, and then at 16°C for 7 d. In a bench‐scale fermentation in a 5‐L jar fermenter, 20:4ω3 production reached 1.60 g/L of culture medium on the eighth day (corresponding to 77.3 mg/g dry mycelia and 26.0% of total cellular fatty acids). The cellular lipids of the S14 strain comprised 75.8% triacylglycerol (TG), 6.7% diacylglycerol, and 13.3% phospholipids (PL). The percentage of 20:4ω3 was higher in PL than in TG, and highest in phosphatidylcholine (32.6%).