Microbial conversion of an oil containing α‐linolenic acid to an oil containing eicosapentaenoic acid

Abstract

Abstract Mycelia of arachidonic acid‐producing fungi belonging to the genus Mortierella were found to convert an oil containing α‐linolenic acid to an oil containing 5,8,11,14,17‐ cis ‐eicosapentaenoic acid (EPA). This conversion was observed when they were grown in a medium containing the oil, glucose and yeast extract at 28 C. On the screening of various oils, linseed oil, in which α‐linolenic acid amounts to about 60% of the total fatty acids, was found to be the most suitable for EPA production. Under the optimal culture conditions, a selected strain, Mortierella alpina 20‐17, converted 5.1% of the α‐linolenic acid in the added oil into EPA, the EPA production reaching 1.35 g/l of culture broth (41.5 mg/g dry mycelia). This value corresponded to 7.1% (by weight) of the total fatty acids in the extracted lipids. The lipid was also found to be rich in arachidonic acid (12.3%). Other major fatty acids in the lipid were palmitic acid (4.4%), stearic acid (3.2%), oleic acid (13.5%), linoleic acid (13.7%), α‐linolenic acid (38.5%) and γ‐linolenic acid (0.9%).