The Industrialisation Produce, Fatty Acid Distillation And Application Of Schizochytrium Limanium OUC88

This thesis is about a heterotrophic marine fungal Schizochytrium limacinum OUC88. It mainly studied the effect envirmental factors on both the bacterial cell growth and products synthesis in suspension culture. In order to industrialize the whole process, the middle-scale culture in 10L,100L fermentor and the extraction methods were studied. The result are as follow:1. Fermentation parameters for biomass and DHA production of Schizochytrium limacinum OUC88 in a fermenter (working volume 7 L) were optimized using Plackett-Burman and central composite rotatable design. Out of 10 factors studied by Plackett-Burman design, four influenced the biomass production significantly. Central composite rotatable design was used to optimize the significant factors and response surface plots were generated. Using these response surface plots and point prediction, optimized values of the factors were determined as follows temperature 23℃, aeration rate 1.48 L min-1 L-1, agitation 250 rpm and inoculum cells in mid-exponential phase, the maximum yield of DCW and DHA were 24.1 g L-1 and 4.7 g L-1, respectively. These predicted values were also verified by validation experiments. The kinetic equation of bacterium cultured was: X=9.19*e0.08t/(24.46-0.37*e0.08t); The kinetics of DHA production was P = -0.25 + 0.2X2. The rotifer and Artemia were harvested at 3, 6, 9, 12, 18 and 24 h intervals, analyzed for their fatty acid composition, and compared with the control which fed on yeast only. The highest DHA content resulted from the enrichment period of 12 h for both fed organisms, reached to 13.4% and 10.9% of the total fatty acids (TFAs) in rotifers and Artemia nauplii, respectively, and the DHA level has reduced sharply if enrichment time longer than 12 h. The pseudoalbinism rate of turbot Scophthatmus maximus juveniles which fed on enriched rotifers and Artemia nauplii has reduced significantly (40% lower than in control group), suggesting that enriched rotifers and Artemia nauplii by DHA-rich Schizochytrium limanium OUC88 may provide a practical strategy for fish juveniles in aquaculture.3. In DHA extraction process, the optimum values of parameters of the extraction were determined by Orthogonal design experiment.