摘要

Polyunsaturated Fatty Acids (PUFA) of the n-6 and n-3 series play important roles in nutrition. Microorganisms are important sources of n-6 and n-3 fatty acids;however, most produce either n-6 or n-3 fatty acids as the major PUFAs and very few produce both. This differential production suggests that PUFAs metabolic pathway is strictly controlled in microorganisms. The major pathway of n-6/n-3 faty acids biosynthesis in lower eukaryotes is composed of Δ12 Desaturase (Des), ω3 Des (Δ15, Δ17), Δ6 Des, Δ6 Elongase (Elo), Δ5 Des, Δ5 Elo and Δ4 Des, among which Δ6 Des and Δ15 (ω3) Des, located at the branch point of PUFAs metabolic pathways, are key regulators of the flux of linoleic acid (18:2 n-6) into either n-6 or n-3 fatty acid metabolic pathways. These latter two enzymes work together as a molecular switch that control the production of n-6/n-3 fatty acids. However the mechanism of the molecular switch is, so far, not clear. This review summarizes the recent advancement of the molecular base of the differentail production of n-6 or n-3 PUFAs in microorganisms.

全文