Selective Production of Polyunsaturated Fatty Acids by the Fungus Mortierella alpina 1 S-4 and Its Mutants

Abstract

Mycelia of a fungus Mortierella alpina 1 S-4, which was isolated from soil, and the mutants derived from it were found to be new and rich sources of C20 polyunsaturated fatty acids (PUFAs) of pharmacological and dietary importance. M alpina 1 S-4 produced a unique triacylglycerol oil with high ω 6 PUFA content. The mycelial content of arachidonic acid reached 274 mg/g dry mycelia (4.3 g/L) on cultivation of the fungus in a medium containing glucose and yeast extract. The value accounted nearly 70 % of the total fatty acids in the extracted oil. The same fungus produced dihomo-γ-linolenic acid (DGLA, 2.17 g/L) when grown with sesamin, a specific inhibitor of Δ5 desaturase. A mutant defective in 5 desaturase also produced DGLA (4.1 g/L). Another mutant which is defective in Δ12 desaturase produced anoil containing only ω 9 PUFAs. The mycelial mead acid content reached 141 mg/g dry mycelia (1.9 g/L). An oil rich inω3 PUFAs was produced by the same mutant when grown in a medium containing linseed oil.The content of total co 3 PUFAs (i. e., a ?linolenic acid + cis-8, cis-11, cis-14, cis-17-icosatetraenoic acid + cis-5, cis-8, cis-11, cis-14, cis-17-icosapentaenoic acid) reached nearly 50 % in total mycelial fatty acid.