由於近來對石化燃料需求的劇增和溫室氣體造成的溫室效應之議題促使人們尋找可替代性的能源。從油脂微生物獲取微生物油脂被視為是一個非常具有潛力的生質柴油來源。油脂微生物可以產生大量的油脂且其油脂成分與植物油很類似。
米糠為碾米過程中低價值之副產物且其全世界產量相當龐大。經去油後，去脂米糠仍含有大量的碳水化合物。有潛力成為微生物發酵之營養源。
本研究探討利用去脂米糠水解液來培養Yarrowia lipolytica Po1g以生產油脂之可行性。米糠利用索氏萃取除油步驟後，探討不同的酸濃度(1-4% v/v) 、水解溫度(60-120oC)和反應時間(1-8 h)對去脂米糠水解後水解液中醣類濃度之影響。以3%的稀硫酸溶液在90oC 下反應6小時可得最大醣含量。水解液接著進行去毒化步驟，目的是降低去脂米糠水解液中5-羥甲基糠醛和夫喃甲醛的含量以提高Yarrowia lipolytica Po1g之發酵效率。本研究所得之最佳生物量、油脂含量和油脂產率分別為10.75 g/L 、48.02%和1.72 g/L/day。

The increasing demands of petroleum-based fuel and concerns about greenhouse gas have triggered the search for alternative fuel. Recently, microbial oil from oleaginous microorganism is considered as a potential candidate for biodiesel production. Oleaginous microorganism possesses high content of lipid with similar fatty acid composition to that of vegetable oil.
Rice bran is an undervalued by-product from rice milling and is produced in large quantity worldwide. After the oil is being removed, a significant part of defatted rice bran is polysaccharide which can be considered as a potential source of sugars for microbial fermentation.
The purpose of this study is to investigate the possibility of utilizing the hydrolysate of defatted rice bran as an alternative substrate for culturing Yarrowia lipolytica for microbial oil production. After removing oil from rice bran by Soxhlet extraction, the bran is subjected to acid hydrolysis with various sulfuric acid concentrations (1-4%v/v), reaction times (1-8h) and reaction temperatures (60-120oC). The optimal conditions in terms of total sugar produced were found to be 3% sulfuric acid at 90 oC for 6 h. The hydrolysate was subsequently detoxified by neutralizing to decrease the amount of inhibitors such as 5-hydroxymethylfurfural (HMF) and furfural in the defatted rice bran hydrolysate to increase its potential as a medium for culturing Yarrowia lipolytica. Dry cell mass, lipid content and lipid productivity of Yarrowia lipolytica grown under optimum conditions were 10.75 g/L, 48.02% dry cell mass and 1.72 g/L/day, respectively.

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