Industrial production of dihomo-γ-linolenic acid by a Δ5 desaturase-defective mutant of Mortierella alpina 1S-4 fungus

Dihomo-gamma -linolenic acid (DGLA)-containing oil (triacylglycerol) was produced by the fungus Mortierella alpina S14, which is a Delta5 desaturase-defective mutant of the arachidonic acid-producing strain 1S-4. Using soy flour as the nitrogen source, S14 produced 8.1 g DGLA/L of culture medium in a 50-L jar fermenter. Shifting the cultivation temperature from 26 to 28 degreesC resulted in reduction of the percentage of DGLA in total fatty acids. Under optimal conditions in a 10-kL industrial fermenter, DGLA production reached 7.0 g/L (percentage of DGLA, 43.9%) at day 12 of cultivation. The other fatty acids were palmitic (18.2%), stearic (7.9%), oleic (7.5%), linoleic (4.4%), gamma -linolenic (3.2%), arachidonic (0.4%), and lignoceric (7.7%) acids.