Mead acid production by disruption ofd12-desaturase gene in Mortierella alpina 1S-4

August Mead acid (MA; 20:3u9) is one of the u9 series of polyunsaturated fatty acids (PUFAs). MA is used to inhibit the inflammation of joints and is applied to the medicinal or health food field. We aimed to construct MA-producing strains with disruption of the D12-desaturase gene (D12ds) via an efficient gene-targeting system using the lig4-disrupted strain of Mortierella alpina 1S-4 as the host. The transformants showed a unique fatty acid composition that only comprised u9-PUFAs and saturated fatty acids, while u6-and u3-PUFAs were not detected, and the total composition of u9-PUFAs, including oleic acid (18:1u9), 18:2u9, 20:1u9, 20:2u9, and MA, was up to 68.4% of the total fatty acids. The MA production in the D12ds-disruptant reached 0.10 g/L (8.5%), which exceeded 0.050 g/L (4.6%) in the conventional D12ds-defective mutant JT-180.