Production and Application of Single Cell Oils Containing C20 Polyunsaturated Fatty Acids

Abstract

Mycelia of a fungus Mortierella alpina 1S-4 and the mutants derived from it are new and rich sources of C20 polyunsaturated fatty acids (PUFAs) of pharmacologically and dietary importance. M. alpina 1S-4 producs a unique triacylglycerol with high n-6 PUFA content. The mycelial content of arachidonic acid reaches 274 mg/g dry mycelia (4.3 g/L) on cultivation of the fungus in a medium containing glucose and yeast extract. The value accounts nearly 70 % of the total fatty acids in the extracted oil. Mutants defective in A 5 desaturase are potent produces of dihomo-γ-linolenic acid (4.1 g/L). A Al2 desaturase-defective-mutant produces an oil containing only n-9 PUFAs. The mycelial Mead acid content is 141 mg/g dry mycelia (1.9 g/L). An oil rich in n-3 PUFAs can be produced by the same mutant when grown in a medium containing linseed oil. The content of total n-3 PUFAs (i.e., α-linolenic acid+8, 11, 14, 17-cis-icosatetraenoic acid+5, 8, 11, 14, 17-cis-icosapentaenoic acid) is nearly 50 % in total mycelial fatty acid. The enzyme systems for the biosynthesis of PUFAs in the Mortierella fungi is also discussed.