Fermentation strategies of ω-3 poly-unsaturated fatty acids production from Schizochytrium limacinum SR21

• Main Authors: Ching-An Lai, 賴鏡安
• Other Authors: 藍祺偉
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/67768344611964562814

碩士 === 元智大學 === 化學工程與材料科學學系 === 98 === Bio-energy and biodiesel has been approved to reduce the greenhouse effect and secure the energy supply. However the waste glycerol derived from biodiesel production became an environmental issue. In this study , an approach of using glycerol as the substrate to produce polyunsaturated fatty acid (PUFA) by microalgae was examined. Deoxyribonucleic acid (DHA) is a PUFA which can not synthesized by human but has been demonstrated helpful in preventing heart and circulatory disease and facilitating brain development in infant. Schizochytrium limacinum SR21 is a heterotrophy microalgae which can use glycerol to produce DHA. Using concentration 20 g L-1 of glucose as carbon source can accumulate 47.37% (w/w) of total lipid which have content of 39% DHA (185 mg g-1). It can produce 43.15% (w/w) of total lipid which consists of 39% DHA (213 mg g-1) by using glycerol as substrate at concentration 20 g L-1. Complex nitrogen is favored for DHA accumulation. DHA content was higher when cultivation was carried out at initial pH value of 7. DHA content increase from 43.79 mg g-1 to 108.16 mg g-1 when increase dissolved oxygen (DO) inside the shaker system . High C/N ratio and vitamin B12 displayed insignificant impact upon DHA accumulation. However 47.32%(w/w) total lipid of biomass and 17%(84.43 mg g-1) DHA of total lipid accumulated when concentration of crude glycerol 20 g L-1 The pH control fermentation showed a better result of DHA accumulation than pH non-controlled fermentation by of the Schizochytrium limacinum SR21. The DHA production is three-fold higher (0.061:0.200 mg g-1). Biomass accumulated rapidly and demonstrated the best specific growth rate 2.74 d-1 under the DO50% cultivation. However it showed an advantaged on DHA synthesis at the lower DO surrounding (DO10%). Combining both fed-batch concentration of substrate 20 g L-1 and two stage DO fermentation strategy have the specific growth rate 2.04d-1 and the rate of DHA production 2.018g L-1 d-1.