Cloning And Characterization Of CDNA Encoding Δ～9 Fatty Acid Desaturase Of Mortierella

Unsaturated fatty acids (UFAs) including linoleic acid, γ-linolenic acid, dihomo-γ-linolenic acid, arachidonic acid and eicosapentaenoic acid (EPA) have played important roles in prevention and treatment of heart disease and high blood pressure, in the inflammatory area (for example, treatment of asthma, arthritis and psoriasis) and for some cancer treatment Natural sources of UFAs are animal and plant, such as EPA in fish oils, arachidonic acid in porcine liver and y -linolenic acid in Oenothera biennis L.. For production of UFAs is easily affected by environmental conditions, for example climate, it cant meet the needs of the society. Researcher have paid great attention to producing UFAs using microorganism due to several advantages of microorganism such as high growth rate, simple culture condition and no raw material limit Output of UFAs is determined by yield of mycelium and UFAs content of mycelium, but conditions for growth of cell is contrary to accumulation of high content of UFAs, thus UFAs exclusive of γ -linolenic acid haven't realized industrialization yet. Currently the focal point of fermentative production of UFAs using microorganism is screening for strain of high productivity. Genetic engineering has developed rapidly recently and possesses unparalleled advantages over traditional breeding. Through regulation of key enzymes in biological synthetic pathway of UFAs at molecular level, it's possible to improve synthetic ability of strain to a great extentThis dissertation has investigated mainly the possibility of reforming the producer of UFAs—Mortierella by genetic engineering. Δ~9 fatty acid desaturase catalyses the oxidation of palmitoyl-CoA and stearoyl-CoA at the Δ~9 position to form the monounsaturated fatty acyl-CoA esters, palmitoyl-CoA and oleoyl-CoA, respectively. Thus it's the key enzyme in determining the unsaturation extent of fatty acid.The optimal methods for isolating DNA, RNA and plasmid from Mortierella were studied, which lay solid foundation for molecular manipulation henceforth.The cDNA library of Mortierella was constructed using λgt10 vector, which make cloning genes for other key enzymes and studying lipid metabolism of Mortierella...