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Mead acid (MA; 20:3ω9) is one of the ω9 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 Δ12-desaturase gene (Δ1 2ds) 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 ω9-PUFAs and saturated fatty acids, while ω6-and ω3-PUFAs were not detected, and the total composition of ω9-PUFAs, including oleic acid (18:1ω9), 18:2ω9, 20:1ω9, 20:2ω9, and MA, was up to 68.4% of the total fatty acids. The MA production in the Δ1 2ds -disruptant reached 0.10 g/L (8.5%), which exceeded 0.050 g/L (4.6%) in the conventional Δ1 2ds -defective mutant JT-180. [ABSTRACT FROM AUTHOR]

ω3-Docosapentaenoic acid (ω3-DPA), an ω3-polyunsaturated fatty acid (ω3-PUFA), is expected to have beneficial physiological functions to humans; however, because of its rarity in nature, it has not been fully analyzed. We isolated an ω3-DPA producing microorganism strain T7 from brackish areas in Japan. Although most oleaginous microorganisms rarely accumulate ω3-DPA (<5% of total lipid), strain T7 accumulated ω3-DPA with more than 20% of total fatty acids. The strain T7 was identified as a related species of Aurantiochytrium. In Aurantiochytrium sp. T7, ω3-DPA production reached 164 mg/L culture broth, and the ω3-DPA content reached 23.5% of the total fatty acids when cultivated in a medium containing 2% glucose as the carbon source and 1% yeast extract as the nitrogen source, with a salinity equivalent to 50% of that of seawater and a pH in the acidic range (pH < 5.5). Aurantiochytrium sp. T7 is a promising producer of high-purity ω3-DPA containing-lipid for the functional analysis of ω3-DPA whose physiological function has hardly been elucidated, and a useful strain for investigating the novel metabolic pathway of fatty acids. [ABSTRACT FROM AUTHOR]

Linoleic acid Δ9 hydratase, which is involved in linoleic acid saturation metabolism of Lactobacillus plantarum AKU 1009a, was cloned, expressed as a his-tagged recombinant enzyme, purified with an affinity column, and characterized. The enzyme required FAD as a cofactor and its activity was enhanced by NADH. The maximal activities for the hydration of linoleic acid and for the dehydration of 10-hydroxy- cis -12-octadecenoic acid (HYA) were observed at 37 °C in buffer at pH 5.5 containing 0.5 M NaCl. Free C16 and C18 fatty acids with cis -9 double bonds and 10-hydroxy fatty acids served as substrates for the hydration and dehydration reactions, respectively. The apparent K m value for linoleic acid was estimated to be 92 μM, with a k cat of 2.6∙10 −2 s −1 and a Hill factor of 3.3. The apparent K m value for HYA was estimated to be 98 μM, with a k cat of 1.2∙10 −3 s −1 . [ABSTRACT FROM AUTHOR]

A ω3-fatty acid desaturase gene (maw3) which is involved in biosynthesis of n-3 polyunsaturated fatty acids (PUFAs) was previously isolated from Mortierella alpina 1S-4. In this report, we investigated the products of MAW3 catalyzing reaction with endogenous and exogenous fatty acids in the yeast transformant. Two unusual fatty acids de novo synthesized in the yeast transformant expressing maw3 gene were identified as n-4 hexadecadienoic acid (16:29cis,12cis ) and n-1 hexadecatrienoic acid (16:39cis,12cis,15) by GC–MS and 1H NMR analyses. In addition to the desaturation activity at the ω3-position for 18- and 20-carbon PUFAs, MAW3 in the yeast transformant inserted a double bond at Δ12-position of endogenous palmitoleic acid (16:19cis ) and further at Δ15-position of the resulting 16:29cis,12cis to result in the formation of 16:39cis,12cis,15 leading to a bifunctional Δ12/Δ15-desaturase for 16-carbon fatty acids. Moreover, we evaluated the activity of MAW3 in the yeast transformant under different temperatures. The MAW3 did not have desaturation activities in M. alpina 1S-4 at 28°C but it had in the yeast transformant for various fatty acids. The MAW3 was demonstrated to be a trifunctional Δ12/Δ15/ω3-desaturase, exhibiting Δ12-desaturation for 16:19cis , Δ15-desaturation for 16- and 18-carbon fatty acids that had a preexisting cis-double bond at Δ12 position, and ω3-desaturation for 20-carbon fatty acids having that at Δ14-position. It is the first report that the fatty acid desaturase (MAW3) is shown to have Δ12- and Δ15-desaturation activities for a 16-carbon fatty acid, in addition to its major function, ω3-desaturation activity. [ABSTRACT FROM AUTHOR]

Researches related with the application of functional lipids such as polyunsaturated fatty acids (PUFAs) have been conducted in various fields with a view to health and dietary requirements. Novel rich sources other than known natural sources such as plant seeds and fish oils are required for increasing demands of PUFAs. The filamentous fungus Mortierella alpina 1S-4 produces triacylglycerols rich in arachidonic acid, i.e., ones reaching 20 g/l in concentration and containing 30–70% arachidonic acid as total fatty acids. Various mutants derived from M. alpina 1S-4 have led to the production of oils containing various PUFAs. Molecular breeding of M. alpina strains by means of manipulation of the genes involved in PUFA biosynthesis facilitates improvement of PUFA productivity and elucidation of the functions of their enzymes. This review describes practical PUFA production through mutant breeding, functional analyses of the genes of the enzymes involved in PUFA biosynthesis, and recent advances in unique PUFA production through molecular breeding. [Copyright &y& Elsevier]