- 學位論文
不同碳源前驅物培養嗜鹽菌生產不同化學結構聚羥基烷酯之研究
Different chemical structure of polyhydroxyalkaoates produced from Haloferax mediterranei by using different hydrocarbon precursors
摘要
為了減少石化塑膠的使用，而開發可自然分解或對環境無害與物 化性質相似於石化塑膠的替代材料為現今重要的綠色科技之ㄧ。極端 嗜鹽菌Haloferax mediterranei 為生長於高鹽度環境中，因此不易受 到雜菌污染可以進行長時間不間斷的醱酵培養，而且能夠於體內生產 生物可分解性聚羥基烷酯 (polyhydroxyalknoate, PHA)。但是現今 PHA 的結構多數屬於3-hydroxybutyrate (3HB)單體所組成之硬脆型高 分子材料，若可以在高分子結構中增加3-hydroxyvalerate (3HV)之含 量，則有助於改善PHA 之韌性。本研究中發現當以葡萄糖作為基本 碳源培養H. mediterranei 時，只得到3HV 含量為4.8 % 。若利用農 業廢棄物（例如蔗渣）作為碳源培養H. mediterranei 所得到之3HV 含量亦只有5.3 % 。而若以葡萄糖或大豆水解液為碳源，並於菌體培 養至第34 小時，添加戊酸0.5 g/L 作為誘導前驅物時，則能夠促進菌 體生產含3HV單體達26.0 % (葡萄糖之例)與26.7 % 3HV(大豆水解液 之例)。而若於第34 小時添加戊酸鈉1 g/L 時，則能夠得到35.2 % 3HV(葡萄糖之例)與36.5 % 3HV(大豆水解液之例)。而如果是在培養 至34 小時後添加戊酸0.5 g/L 與戊酸鈉1 g/L 之混合培養液，則可得 37.4±7.2 % 3HV 單體(葡萄糖之例)與48.2±29.6 % 3HV 單體(大豆水解 液之例)。研究中尚發現戊酸鈉能夠刺激H. mediterranei 生長，實驗 中當戊酸鈉的添加量從0.5 g/L 增加至8 g/L，可得到最大菌體濃度 OD520 由11.3 增加至33.1。
並列摘要
In order to decrease the demand of petroleum-based plastic, therefore developing the substitive materials that could decompose naturally and are harmless to environments is becoming one of the most important green technologies. Extreme halophiles, Haloferax mediterranei, could live in the environment of high concentrations of NaCl, and not only could be cultured for long period of time without the risk of microbial contamination, but also produce biodegraded polyhydroxyalkanoates (PHA). The structures of most of PHA are hard and brittle materials composed mostly by 3-hydroxybutyrate (3HB) monomer. The increasing of 3-hydroxyvalerate (3HV) monmer within PHA structure could improve its elongation and toughness. In this research, we find when we use the glucose as the carbon source for cultivating H. mediterranei, we can only get PHA of 4.8 % 3HV. If using the agricultural wastes like ground bagasses as the carbon source to culture H. mediterranei , we still get PHA of low percentage (5.3 %) 3HV. By using glucose or soybean oil hydrolyte as the carbon sources and adding precursors of valerate (0.5 g/L) at cucultivation time of 34 hours can promote producing PHA of 26.0 % 3HV (in case of glucose) and 26.7 % 3HV (in case of soybean oil hydrolyte). By adding 1 g/L sodium valerate at cucultivation time of 34 hours can get PHA of 35.2 % 3HV (in case of glucose) and 36.5 % 3HV (in case of soybean oil hydrolyte). When adding mixture of valerate (0.5 g/L) and sodium valerate (1 g/L) as the precursors at cucultivation time of 34 hours, we can get 3HV of 37.4± 7.2 % (in case of glucose) ; we can get 3HV of 48.2±29.6 % (in case of soybean oil hydrolyte). In the study, we also find that sodium valerate can promote H. mediterranei growing. When increasing sodium valerate form 0.5 g/L to 8 g/L in the culture medium, we can get the maximum cell concentration of OD520nm form 11.3 to 33.1