Research On The Separation And Extraction Technology Of Schizochytrium DHA

DHA(Docosahexaenoic acid), polyunsaturated fatty acid (PUFAs),as the BrainGold, has an important physiological function. It has many functions, such ascardiovascular disease prevention, anti-cancer, anti-allergy and anti-inflammatory. Thetraditional source of DHA was sea fish. Producing DHA via microbial fermentation whichhas many superiorities, has been usedwidely in industrial production. Schizochytrium asDHA producing strain, is used for producing DHA. In this study, we focused on how toextract physiologically active DHA from Schizochytrium. How to extract oil fromSchizochytrium quickly and high yield was the critical step in DHA extraction. Manymethods of cell disruption were used in this study, the results showed that enzymicdegradation had superiority in Schizochytrium cell disruption. Then three kinds ofenzymes were choosed to compare the enzymolysis effects, alcalase was the best choice.On this basis, single factor experiment was designed to determine the optimal treatingconditions with the aim of high oil yield and DHA content. The recycling use of theenzymolysis water was studied. The main results of the study as follows:(1) We compared five methods of cell disruption, the oil yield of vacuum freezedrying and spray drying process were lower than15%. The oil yield after acid-hot processand physical crushing treatment were lower than30%. The oil yield after enzymicdegradation was73.90%, which was the highest..So we confirmed enzymic degradationwas the best method of cell disruption.(2) We compared the effect of different enzymes neutral cellulase, acidic cellulaseand alkaline protease for cell disruption. The oil yield and the concent of DHA afteralkaline protease treatment were71.46%and77.25%respectively. The oil yield and theconcent of DHA were zreo by acidic cellulase treatment while,31.40%and71.26%byneutral cellulose treatment. Hence, we confirmed that alkaline protease was the bestenzyme with wide source and low cost for cell disruption. The dissociation of cellstructure after alkaline protease enzymolysis was mainly in half an hour and the rest oftime was for the non-cell structure dissociation. (3) After aboved the experiments, the best conditions of enzymic degradation wereconfirmed. Temperature, pH, the amount of enzyme, cell concentration and time wereconsidered to design the experiments to determine the optimal conditions. When thebiomass of the strain in fermentation broth reached17.5g/L, the highest oil yield was up to93.20%. when the pH was9.0, the highest concent of DHA was93.19%. The availabilityfor recycling use of the enzymolysis water was studied. The results showed that theenzymolysis water could be repeated for six times at most.