Screening Strains Of High Eicosapentaenoic Acid Yield And Optimization Of Fermentation Condition

Eicosapentaenoic acid (EPA), namely 5,8,11,14,17-eicosapentaenoic acid, belongs to theω-3 polyunsaturated fatty acids, is the essential polyunsaturated fatty acid in human body. It plays a major role in anti-hemoglutination, anti-cancer, anti-inflammation, prenventing angiocargpy and arteriosclerosis, preducing the fat in the blood. Production of eicosapentaenoic acid by microorganisms is the hotspot in recent years because of its merits such as the short cycle, free effect in material and environment, season, weather.A fast and effective method to isolate strains of high eicosapentaenoic acid yield was established.Using the plant organization to concentrate the pythium strain from the soil, and dyes with the sudanese dye dyeing to the hypha, high fat content strain was got to further research.After two method unions effectively screened fast from the soil to eicosapentaenoic acid high production strain D283. The primitive eicosapentaenoic acid content of this strain is 6.51%, eicosapentaenoic acid output is 80.01mg/L.Through the hypha shape, the fatty acid ingredient analysis and 18S rDNA sequence analysis appraisal this strain is pythium.In this research, we discovered the vaccination quantity in 3-10%, the temperature 25-30℃, increasing soybean oil could prevent the pythium D283 hypha to become group, and caused the hypha to favor the vaccination, the growth and the EPA accumulation.The optimal culture medium of pythium D283 to produce eicosapentaenoic acid were studied.The optimal medium contained 100 g/L rice noodle hydrolisis fluid, 5 g/L yeast powder and 1 g/L Na2HPO4.Secondly the effects of pH,inoculum and temperature on production of EPA by pythium D283 were investigated, pH 4.0, an amount of 8%(v/v)and 28-20℃changes the temperature two steps were optimal for EPA production. The EPA yield reach highest 674.55 mg/L when the glucose was 120 g/L and cultured for 8 d.The time courses of consumption of main nutrition composition, fungal biomass, lipid and eicosapentaenoic acid accumulation were investigated on a shaker flask scale.Low initial concentration of glucose and nitrate were good to shorten the lag phase of fungal growth. The initial nitrogen concentration has little influence to the fungal biomass. The highest lipids in biomass appear after the glucose exhausts. eicosapentaenoic acid content assume the S change, in the initial period, eicosapentaenoic acid content are high, along with fungal's growth, eicosapentaenoic acid content instead drops, then eicosapentaenoic acid content increase gradually after the glucose concentration is lower than 10 g/L.