Abstract
Accumulation of free unsaturated fatty acids, added individually to the medium, into cellular triacylglycerol (TG) were examined using a fungus, Mucor hiemalis HA-30, which could produce the eicosapentaenoic acid (20:5n-3)-enriched TG. Linoleic (18:2n-6), γ-linolenic (18:3n-6), arachidonic acids (20:4n-6), and 20:5n-3 were favored for accumulation in TG and each fatty acid accumulated in TG at about 80% purity. However, docosahexaenoic acid (22:6n-3) was not efficiently accumulated in TG and its content was about 60%.
Incorporation and accumulation of various fatty acids added to the cultivation medium were investigated using a model fatty acids mixture. Generally, unsaturated fatty acids were efficiently incorporated into cells more than saturated fatty acids. Fatty acids with odd-numbered double bonds such as 18:3n-3, 18:3n-6, and 20:5n-3 showed the higher incorporation efficiency compared with those with even-numbered double bonds such as 18:2n-6, 20:4n-6, and 22:6n-3. On the other hand, saturated and monounsaturated fatty acids of 16:0, 18:0, and 18:1 were preferentially accumulated in microbial cells over other fatty acids.
