Studies On High Efficient Biosynthesis And Directional Transformation Of Arachidonic Acid

Arachidonic Acid (AA) is the metabolizing hub of theω-6 polyunsaturated fatty acids, which participates in many human metabolizing activities and plays a role in physiological processe of many diseases. It has great commercial value due to its comprehensive application approaches and promising exploitation foreground. M.alpina M2 is considered as a potential candidate used to study on high efficient synthesis and directional transformation of AA, in order to get a high yield and high transformation of AA. The results are as follows:1. The C/N ratio of optimum culture medium is 44, the initial pH value is 6.5, after adding some NADPH regulator such as bean sprouts liquor and glutamic acid, the strains has a flocculent and pelletized appearance, the mass transfer effect is good, which accelerates the strains's growth and accumulation of lipid, AA yield is as 1.32 times as before optimization.2. Adding soybean oil in culture medium could increase yield of lipid, but it will restrain synthesis of AA. AA yield is 3.0 g/L when adding 0.5 % optimum soybean oil.3. Choosing peanut meal as complex nitrogen source can promote strains's growth and accumulation of lipid, but it has an obvious restraining effect on synthesis of AA. After using organic solvent to make sure the active fraction of peanut meal, we choose peanut protein instead of peanut meal in order to increase AA yield. The yield is 5.7 g/L when adding 25 g/100 ml of peanut protein, which is as 1.86 times as basic culture medium.4. This paper confirms feed mode by studing on strains's growth curve and metabolism curve of nutriment. The best way to fed batch fermentation is doing it after fermentation 2d in 2 times. Flow feeding in 45 g/L of dextrose, 3 g/L of yeast powder and 1 g/L KNO3 & NaNO3 on 5d will get 5.07 g/L AA. If M.alpina M2 is given scale-up culture in a 10 L fermentor, AA yield will reach 1.87 g/L.5. It is considered that low temperature fermentation is selected after fermentation is useful of directional transformation of AA. Low temperature fermentation for M.alpina M2 could use the method of treating 5d in culture medium directly after fermenting 8d. Keeping 20℃temperature and 180 r/min rotation speed are propitious to mass transfer of the strains and environment. In the mean time, feeding in 20 g/L of dextrose, 1 g/L of KNO3 & NaNO3, 0.5 g/L of CaCl2 as well as 2 % of ethanol will promote AA yield.