Production of 8,11,14,17‐cis‐eicosatetraenoic acid (20:4ω‐3) by a Δ5 and Δ12 desaturase‐defective mutant of an arachidonic acid‐producing fungus Mortierella alpina 1S‐4

A Δ5 and Δ12 desaturase‐defective mutant of an arachidonic acid‐producing fungus, Mortierella alpina 1S‐4, produced 8,11,14,17‐ cis ‐eicosatetraenoic acid (20:4ω3) intracellularly when grown with linseed oil. Dihomo‐γ‐linolenic acid was the only C 20 polyunsaturated fatty acid (4.9 wt% of total mycelial fatty acids) other than 20:4ω3. AA and 5,8,11,14,17‐ cis ‐eicosapentaenoic acid were not detected. The mycelial lipids consisted of 82.2% (by mol) triacylglycerol (TG), 7.1% diacylglycerol, 8.9% phospholipids (PL), and 1.9% free fatty acids. The percentage of 20:4ω3 was higher in PL (30.1%) than in TG (11.6%), and highest in phosphatidylcholine (38.9%). Under the optimal conditions with a 5‐L jar fermenter, 20:4ω3 production amounted to 97.4 mg/g dry mycelia with a mycelial yield of 23 g/L on the twelfth day (corresponding to 2.24 g/L medium and 37.1% of total mycelial fatty acids).