Production of 5,8,11-eicosatrienoic acid by a Δ5 and Δ6 desaturation activity-enhanced mutant derived from a Δ12 desaturation activity-defective mutant of Mortierella alpina 1S-4

Abstract.

Enhanced production of 5,8,11-eicosatrienoic acid (Mead acid, 20:3ω9) was attained with a mutant fungus, Mortierella alpina JT-180, derived from Δ12 desaturation activity-defective and Δ6 desaturation activity-enhanced M. alpina M209–7. Production of 20:3ω9 by JT-180 was 1.4 times greater than that of the parent strain M209–7. This is thought to be due to its enhanced Δ5 desaturation activity, which was 3.3 times higher than that of M209–7. In both strains, 78.5–80.4% of the total lipids comprised triacylglycerol (TG), and 76.6–79.0% of 20:3ω9 was present in TG. Comparing the fatty acid compositions among various lipid species, the highest percentages (24.1–37.6%) of 20:3ω9 in total lipids were found in phosphatidylcholine. For optimization of 20:3ω9 production by JT-180, a glucose concentration of 4% in the culture medium and shifting of the growth temperature from 28°C to 20°C on the 2nd day were shown to be effective. Under optimal conditions, 20:3ω9 production by JT-180 reached 1.92 g/l culture medium in a 10-l jar fermentor (corresponding to 81.5 mg/g dry mycelia and 18.3% of total fatty acids), which is greater than that reported previously from M209–7 (1.65 g/l).