Conjugated Unsaturated Fatty Acid Bio-synthesis Of Research

Conjugated unsaturated fatty acids containing two or more conjugated double bonds have been found numerous biological actions, including: anticarcinogenic effect, antiatherogenic effect, stimulating the immune response, reducing body fat, enhancing bone formation, and anti-diabetic effect. Particularly Conjugated linoleic acid (CLA) has attracted wide interest. Meanwhile, Oleaginous microorganisms have been one of the hot issues in the field of industrial industrial microbiology owing to the ability of accumulating microbial oil with similar fatty acid composition to that of plant-based oil over 20% of their biomass. The semi-biological synthesis method of CLA was studied initially in this dissertation.42 endophytic fungi of Taxus yunnanensis were selected to screening for oleaginous strains. according to the Sudan IV staining method, red brown intracellula lipid bodies of 18 strains were observed through optical microscope firstly. And secondly the Folch method was adopted to determine the total lipid content of these strains. The number of strains whose lipid yield exceeds 15% is 6, and the lipid yield of strain No. E1.3 is highest, reaching 25.2%.In order to increase the lipid output, the effects of different influence factors including carbon sources,nitrogen sources,carbon-nitrogen ratio,temperature,inoculation period and oxygen quantity dissolved in broth were examined. The better medium for the fermentation was found as follow: 60 g dextroglucose, 2 g yeast extract, 2 g Potassium Nitrate, 2 g Potassium Dihydrogen Phosphate, 0.2 g Sodium Chloride, 0.4 g Magnesium Sulfate, and 5 mL solution containing trace component in 1 L water. The optimal culture condition was 100 mL liquid medium being inoculated in 250-mL Erlenmeyer-flask, rotation speed as 180 r/min, 28℃for 6 day. Under the optimized conditions, the biomass was 10.4 g dry cell /L and the lipid yield is 0.322 g oil/g dry cell.In the meanwhile, a suitable lipid extraction procedure is also very important on fungi lipid production. 6 different mycelium destruction methods and 5 different lipid extraction methods were tested to determine a suitable process. The results show that mechanical homogenizing is the best mycelium destruction method and the Folch method is superior to the other lipid extraction method.Gas chromatography /mass Spectrometry was used to study the fatty acid profiles of the fungal oil of E1.3. And the relative content of LA up to 31.6% is highest according to the normalization method of area. Then conjugated linoleic acids were prepared from fungal oil by alkali isomerization using KOH as catalyst and 2-Butoxy Ethanol as solvent for the first time. UV spectra analyzed the effects of 3 factors on the rate of conversion of LA, and the suitable conditions for the preparation process were found: reaction temperature of 140℃, reaction time of 3 h, m(KOH):m(oil) = 0.3:1. Under the optimum conditions, the average rate of conversion of LA could reaches 86%. The results show that fungal oil maybe a potential alternative source of vegetable oil as the raw materials of CLA.