Fermentation Optimization Of Docosahexaenoic Acid By Schizochytrium Sp.

Docosahexaenoic acid(DHA)is a kind of long chain?-3 highly unsaturated fatty acids(PUFAs)with important physiological functions.It's difficult of the synthesis of DHA in human body,so it needs to be taked from dietary.The traditional source is from fish oil with many disadvantages such as unstable yield and too complicated ingredients.It's also a feasible way to harvest DHA by fermentation using marine microalgae,from which high quality,stable oil ingredients and convenient purification was possible,and the yield could be optimized to be higher.Mass industrial production has already been achived,while related research is taking place in China but the low cost and high yield is so far not achived.The fermentation medium of HCCB30108 producing DHA was optimized.The composition and concentration of carbon source,nitrogen source and salt source were firstly researchedin flask.The best flask fermentation medium flask was(g/L):glucose 60,corn steep liquor(CSL)powder 15,Na₂SO₄13,Mg SO₄·7H₂O 2.Then the optimization was carried out in 5L fermentation jar.,and the best fermentation condition was determined.The concentration of glucose should be higher than 1%in early period and hight than 3%after then.As for nitrogen souce,0.25%(m/v)of CSL should be pumped into the jar 24hours or 48hours seperately after the beginning of fermentation.Stirring speed should be higher in first 72 hours and lowered then to get high DHA productivity.Finally the fermatation was carried out in 50L scale-up jar,a dry cell weight of 85.5g/L and DHA productivity of 8.05g/L was achived.,which lay a foundation for the further optimization and industrial production.