- 學位論文
以Ralstonia eutropha H16進行粗甘油加值化合成聚羥基烷酯醱酵研究
Fermentation strategies of polyhydroxyalkanoates production from crude glycerol by Ralstonia eutropha H16
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摘要
聚羥基烷酯是儲存在細胞體內的一種生物性聚酯高分子，其具有生物相容性與生物可分解性，環境中有許多細菌可以行體內合成，以做為細菌自身碳源與能量提供，分子物理性質近似於石化塑膠產品。培養微生物需要足夠的碳源，在醱酵過程中，碳源占了醱酵大部分成本。而目前生質柴油產業蓬勃發展，轉酯化製程產生大量的副產物『粗甘油』廢棄物，而本研究以粗甘油為碳源，利用菌株Ralstonia eutropha H16合成PHB，進而提高甘油利用的經濟效益。將生質柴油製造廠商所提供的粗甘油進行分析，粗甘油純度為80 %、含水率11 %、其他成分包括Na+1、S+2、K+1等微量金屬離子。 本研究進行搖瓶及醱酵槽之PHB醱酵製程實驗；當利用搖瓶生產PHB時，於Nutrient Broth(NB)培養基培養48小時，並控制pH 7、10 % (v/v)接種量、碳氮比為100:1、溫度30 ℃以及甘油濃度上限10 % (w/v)，可得細胞乾重可達4 g L-1且PHB含量為25~45 %；以搖瓶結果改利用Define medium作為培養基，探討粗甘油與酵母萃取物添加量，並以兩公升醱酵槽進行批次醱酵槽的關鍵因子探討，經實驗結果發現，溶氧量須大於50 %、pH不控制、曝氣量為1 vvm，為醱酵槽最適化條件，進而將醱酵槽規模放大至槽體為五公升與五十公升，以五公升醱酵槽培養72小時，並添加5 %粗甘油為碳源，溫度30 ℃、含氧量 50 %，可得細胞乾重38.41g L-1，PHB含量為75.1 %，甘油利用率高達85.2 %，每一克的甘油可產生0.67克的PHB，而PHB的單位時間產率可達到0.40 g hr-1 L-1。本研究成功的利用粗甘油作為碳源，並有效的合成代謝PHB，降低醱酵槽原料成本至6.14 USD kg-1 PHB，以利加值化粗甘油。
並列摘要
The polyhydroxyalkanoates(PHA) have been recognized as good substitutes for the non-biodegradable petro-chemically produced polymers. It can be generated from microbial and regarded as a potential material in several of industrial application. In this study, the crude glycerol (CG) as the carbon source was supplied to Ralstonia eutropha H16 for PHAs accumulation. The economic effect of using glycerol compared to other carbon sources was analyzed in respect of productivity and material cost. The composition of crude glycerol was provided by biodiesel company in Taiwan. It composited 80 %of glycerol, 11 %water, 9 %metal ions and un-puritys. The optimization production was carried out to study the influences of medium conditions supply, temperature and inoculums ratio. The optimization temperature and inoculums ratio for PHAs formation is observed at 30℃ and 10 % (v/v), respectively. The dry cell weight(DCW) can achieve average 4 g L-1 and PHB content was found in the range of 25%~ 45 % (w/w)。 This study was successful used define medium add CG as carbon source culturing Ralstonia eutropha H16. A 2 L fermentor for the batch fermentor of the key factors, the experimental results showed that dissolved oxygen must be greater than 50%, pH does not control, aeration of 1 vvm, the slot for the fermentation conditions optimization. The fermentor scale up to 5 L and 50 L, in the 5L fermentor for 72 hours, PHAs content obtained was 75.1 % (w/w), cell dry weight increased to 38.41 g L-1 and glycerol utilization up to 85.2 %. Each gram of glycerol can produce 0.67 g of PHB, and PHB yield up to 0.40 g hr-1 L-1, reduce the cost of raw materials to 6.14 USD kg-1 PHB.
參考文獻
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