| Gamma-linolenic acid, a polyunsaturated fatty acid, is nutritionally important fatty acid in human and essential for bodies. As precursor of prostaglandin and interleukin, gamma-linolenic can be used to treat hyperlipidemia, diabetes and so on. It is always looked as functional factors and drugs. Oleic acid, linoleic acid, palmitic acid, octadecanoic acid which increase cholesterol in serum are rich in diet fatty acid. While diet fatty acid is short of polyunsaturated fatty acid including gamma-inolenic acid. It is essential for human to take in gamma-linolenic acid. Evening primrose oil containing large number of gamma-linolenic acid has been developed and applied. Because vegetative cycle of evening primrose is too long to produce great number of oil. People have started to develop new resource of gamma-linolenic acid. According to new studies, Microorganism can be used to produce plenty of oil including high gamma-linolenic acid.Gamma-linolenic acid can be produced by fungi, one of microorganism, such as Mortierella isabellina, Mortierella ramanniana, Thamnidium elegans, Mucor hiemalis, Mucor circinelloides, but the abilities produce gamma-linolenic acid are different. In this paper, Mucor circinelloides is found to be a good strain to produce grease including gamma-linolenic acid. To increase its yield, Mucor circinelloides As3.2514, as an original strain, was mutated by diethyl sulfate(DES),5-fluorouracil(5-FU) and UV treatment. Mutant Mc08 was obtained after passing primary-screen and multiple-screen. Compared to those of the initial strain, the biomass and γ-linolenic acid of mutant Mc08 was increased by 12.2% and 7.64% respectively.In this study, the effect of factors related to fermentation was studied. These factors included temperature, rotational speed, pH, inoculation amount, carbon sources, nitrogen sources, inorganic salts. The fermentation medium of Mc08 was studied by orthogonal design L27(313). The optimum medium was of 30% potato, 0.4% peptone, 0.4% yeast extract, 0.3% KH2PO4, 0.15% MgSO4 and 0.01%ZnSO4. The biomass, yield of grease and γ-linolenic acid of mutant Mc08 in optimum medium were up to 10.49g/L,31.7%,25.8%.The biosynthesis of gamma-linolenic acid from linoleic acid with △6desaturase, Mucor circinelloides, is reported. Various factors affecting this process were studied. The results showed that the yield of the gamma-linolenic acid increased with the decrease of the reaction temperature. Adding Zn2+ to the reaction mixture caused a increase of gamma-linolenic acid yield. Gamma-linolenic acid yield reached the maximum at pH7. MgCl2, ATP, CoA and NADPH were important cofactors for the reaction.Microencapsulation of liquid oil rich in gamma-linolenic acid has been studied by G-A method. Various factors related to emulsificatiom and coacervation, including temperature, pH, proportion and concentration of wall materials, ratio of oil to gross material and so on.The optimal pH and temperature of emulsification were 6~7 and 80℃ respectively. And the optimal pH and temperature of coacervation were 4.0~4.5 and 60℃. The experiment showed the proportion of wall materials was 1:1, concentration 2%, the proportion of oil to gross material 20%. |
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