Isolation and characterization of a Δ--desaturation-defective mutant of an arachidonic acid-producing fungus, Mortierella alpina 1S-4

摘要

A mutant, considered to be defective in Δ9-desaturation, of an arachidonic acid-producing fungus, Mortierella alpina 1S-4, was isolated after treating the wild-type spores with N-methyl-N′-nitro-N-nitrosoguanidine. The mycelial FA of this mutant included 38% stearic acid, the level being only 5% for the wild type. Upon growth at 24–28°C, its mycelial lipids included a high level (up to 50 mol% of total mycelial lipids) of FFA, of which about 90 mol% was stearic acid. However, the level of FFA was markedly decreased with a concomitant increase in the IAG level when the mutant was grown at 20°C or lower, or when it was grown in a culture medium supplemented with PUFA.