以微藻Schizochytrium limacinum SR21轉化粗甘油生產二十二碳六烯酸之最適化研究

Docosahexaenic Acid Production from Crude Glycerol by Schizochytrium limacinum SR21

龍韻存(Yun-Tsun Lung)

指導教授 ： 藍祺偉

元智大學/工程學院/化學工程與材料科學學系/碩士(2012年)

摘要

近幾年來全球暖化問題日益嚴重，使得環保再生能源逐漸被受到重視，各國紛紛開始尋找新的替代能源。其中以生質柴油發展最具規模，然而在生產生質柴油的過程中，隨之也衍生副產物粗甘油的問題，這也使得將粗甘油加值再利用生產高單價的產品成為最熱門的課題。本研究以粗甘油生產多元不飽合脂肪酸如：EPA、DHA，以解決生質柴油所帶來粗甘油過剩的問題。
Schizochytrium limacinum SR21為一可利用甘油生產DHA之異營性微藻，經由本研究之搖瓶試驗後發現以粗甘油為基質培養於培養基2，於30 g L-1之濃度下可得到最大比生長速率為0.71 day-1，細胞乾重可達7.8 g L-1，而以50 g L-1濃度的粗甘油培養則有最佳DHA含量，每克藻中含有157.81 mg之DHA生成。溫度和培養方式對於不飽和脂肪酸合成皆有所影響，以混營培養於25℃最適合細胞生長，細胞乾重可達9.03 g L-1，以混營/異營培養於20℃以及30℃下則有利於DHA累積，分別為233.73 mg g-1、222.87 mg g-1。當培養於20℃，是有利於DHA之累積，約為189.80 ~ 200.16 mg g-1。
在Schizochytrium limacinum SR21之醱酵研究結果發現，於溶氧量控制在50 %，pH不控制下較利於細胞之生長以及DHA的合成。當培養在30℃下，細胞乾重為8.74 g L-1 ，總油脂累積含量可達82.77% ，DHA含量為192.83 mg g-1。培養於25℃下，最大細胞乾重於第120小時可以達到10.16 g L-1，每克粗甘油可的細胞乾重的產率為0.43g g-1；在132小時則是可以得到最佳DHA含量為208.20 mg g-1。

關鍵字

微藻 ； DHA ； 粗甘油 ； 溫度 ； 光照週期 ； pH不控制

並列摘要

Development and promotion of biodiesel, a substitute fuel for fossil energy, has resulted in an environmental issue of overproducing crude glycerol. The microalgae can be applied for producing polyunsaturated fatty acid, such as EPA and DHA, from glycerol.
Schizochytrium limacinum SR21 is one of the indigenous marine heterotrophic microalgae and it can utilize glycerol to produce DHA. From the results of shake flask study, we found that maximum specific growth rates was 0.71 day-1 and biomass reached 7.8 g L-1 by feeding 30 g L-1 crude glycerol in medium 2. However, 50 g L-1 crude glycerol had optimal DHA content and its productivity was 157.81 mg-1. The effects of temperature and light supply depicted a significant impact on synthesis of fatty acids. When cell was cultured at 25 ℃ and in mixotrophy, the cell growth was suitable and the biomass reached 9.03 g L-1. Besides, culturing the cell at 20℃ and 30℃ promoted DHA accumulation by mixo/heterotrophic, the productivity of DHA were 233.73 mg g-1 and 222.87 mg g-1, respectively. When culturing at 20 ℃, the cell can accumulate DHA about 189.80 ~ 200.16 mg g-1.
The DO was controlled at 50% and under pH non-control showed a better result of cell growth and DHA accumulation than pH control. When cell was cultured at 30℃, the biomass reached 8.74 g L-1, total lipid had 82.77% and DHA content had 192.83 mg g-1. When cell was cultured at 25℃, the maximum biomass reached 10.16 g L-1 and the biomass yield had 0.43g g-1 in 120 hr. However, culturing the cell in 132 hr can get the best DHA accumulation about 208.20 mg g-1.

並列關鍵字

light cycle ； pH non-control ； DHA ； crude glycerol ； temperature

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