Production of a novel ω1-eicosapentaenoic acid by Mortierella alpina 1S-4 grown on 1-hexadecene

Abstract

An arachidonic-producing fungus, Mortierella alpina 1S-4, was found to accumulate ω-unsaturated fatty acids of C-20 chain length together with ω1-hexadecenoic acid, ω1-octadecenoic acid and so on, when grown on 1-alkenes, i.e., 1-hexadecene and 1-octadecene. The results of mass spectroscopy and proton NMR showed that a C₂₀ polyunsaturated fatty acid (PUFA) is a novel cis-5,8,11,14,19-eicosapentaenoic acid (20:5ω1). This PUFA was obtained at a yield of 0.13 mg/ml culture broth (2.8% of the fungal total fatty acid content) on cultivation of the fungus in a medium containing 4% (v/v) 1-hexadecene and 1% yeast extract at 28°C for 1 week. Investigation of the distribution of fatty acids showed that about 90% (by mol.) of the PUFA was present in the triglycerides and 10% was in the phospholipid fraction. About 70% of that found in the phospholipids was phosphatidylcholine (PC) and the value accounted for ca. 10% of the total fatty acid content. The formation of these ω-unsaturated fatty acids was presumed to occur through the arachidonic acid biosynthetic pathway (n-6 route).