由於近年來對石化燃料的需求劇增再加上80%的主要能源來自於石化燃料，為了減少石化燃料的依賴，因此替代能源的尋找及研究，一直是近年來的熱門議題。從油脂微生物中萃取油脂可被視作生質柴油的潛力來源。此外如何降低培養油脂微生物過程中所需的成本，農業廢棄物的再利用為有效的降低培養成本的方法之一。
米糠是碾米過程中低價值的副產物，在全世界產量龐大。米糠富含碳水化合物，可成為微生物發酵的營養源。本研究利用米糠水解液作為營養源，探討共培養對於生物量及油脂含量的影響。米糠利用稀硫酸進行水解反應成為水解液，探討不同的反應時間、攪拌速度和硫酸的濃度的影響。用2%稀硫酸在90 oC、300 rpm下反應3.5小時可得到最高的水解液醣含量。水解液經去毒步驟，應用於酵母菌Lipomyces starkeyi及微藻Chlorella vulgaris共培養的發酵上。發現共培養的方法無法有效的增加生物量及油脂含量。本研究利用酵母菌Lipomyces starkeyi得到最高的生物量及油脂含量及油脂產量分別為 9.4 g/L、34.30%及3.22 g/L。

The demand of petroleum fuel is increasing and 80% of primary energy is produced from petroleum fuel. In order to decrease the consumption of fossil fuels, alternative renewable fuel has been a hot topic in recent years. Microbial oil from oleaginous microorganism is considered as a potential candidate for biodiesel production. Agricultural waste reused can reduce the cost of oleaginous microorganism for lipid production.
Rice bran is an underused byproduct from rice milling and is produced in large quantity worldwide. Rice bran contains higher polysaccharide which can be considered as nutrient source for microbial fermentation.
In this study, the effect of co-culture on biomass and lipid content using rice bran hydrolysate was investigated. The rice bran was subjected to acid hydrolysis with various hydrolysis time, stirring speed and sulfuric acid concentration. The optimal condition of rice bran hydrolysis was using 2 % sulfuric acid at 90°C for 3.5 h with 300 rpm stirring speed. After detoxifying and neutralizing, the rice bran hydrolysate was used for the co-culture of L. starkeyi and C. vulgaris. It was found that co-culture cannot improve biomass and lipid content. The culturing of L. starkeyi can achieve higher biomass and lipid content than co-culture. The highest biomass, lipid content and lipid production obtained were 9.4 g/L, 34.3% and 3.22 g/L, respectively.

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