| 摘要: | 摘 要 利用微生物系統生產可分解性的材質，來解決全球普遍性的塑膠廢棄物污染問題，是日益重要的課題。由於塑膠所產生的垃圾污染，已造成環境污染上的一大問題，因此生物可分解性塑膠的研究也隨之而起，聚羥基烷polyhydroxyalkanoates (PHAs)為菌體儲存碳源與能量的物質，可以用來當作生物可分解性塑膠的原料。 Kineosphaera limosa是一株由劉文佐博士實驗室在厭氧-好氧活性汙泥系統中發現且分離出來的兼性氧與革蘭陽性菌，在適當菌體生長的情況下會生成聚羥基丁酯-羥基戊酯共聚物(Poly(3-hydroxybutyrate-co-3-hydroxyvalerate), PHBV)，而NADH為生成PHAs時所需之還原力(Reducing power)，菌體在微氧的情況下有利NADH的生成，本研究探討菌體在不同的攪拌速率下對產物PHBV產出的影響，以及調整此菌株生成不同PHB/PHV比例的策略。 搖瓶實驗結果指出微供氧量培養下，三種不同單一碳源：甘油、葡萄醣和醋酸鈉測試，以葡萄醣為單一碳源時產物PHBV有較高產量且其PHV佔全部產物的比例為85%。 發酵槽實驗中，在不同攪拌速率下，其轉速越高下供氧量就越多，在轉速100至200rpm下，體積氧氣傳送係數(kLa)從1.91 hr-1增3.68 hr-1， 可以發現菌體的比生長速率就有越快趨勢從0.009 hr-1至0.024 hr-1。其轉速越高下供氧量就越多，其產生PHB/PHBV比例也不同，由5%至99%，因此攪拌速率下降會使氧氣質傳下降，造成菌體比生長速率下降而會使PHV產出的比例增加。 在兩階段不同攪拌速率，由高轉速切換至低轉速下，攪拌速率由200 rpm經66小時發酵後切換為100 rpm發酵，其結果是因為在200 rpm的條件下，菌體生長速度快而在葡萄醣的消耗速度太快下，不易選擇適當的切換時間點；有了之前的經驗改由低轉速切換至高轉速下，攪拌速率由150 rpm經85小時發酵後切換為220 rpm發酵，未切換前PHB/PHBV為0%，而切換後，所產生PHB/PHBV比例也由17%降至13%。比固定低攪拌速率100 rpm~150 rpm所產生PHB比例5%~6%為高。 Abstract Producing the biodegradable material by using mircoorganism system. It is a more important topic to solve the pollution of plastics in the whole world. The environmental pollution is a big problem as a result of the pollution of plastics. For this reason, people start studying biodegradable material. Biodegradable polymers, poly(3-hydroxybutyric) acid (PHB), and a copolymer, poly(3-hydroxybutyric-cohydroxyvaleric) acid [P(HB-co-HV)], are accumulated inside the cells as reserves. Kineosphaera limosa is a high-G+C Gram-positive, motile, non-spore-forming coccus capable of accumulating significant amounts of polyhydroxyalkanoate (PHA) was isolated from an inefficient biological phosphorus removal activated sludge reactor by Dr. Liu Wen-Tso. The NADH needs reducing power during producing PHAs. And it is good for the bacteria with the few oxygen to producing the NADH. In this study, I researched about different agitation versus producing PHBV and producing different PHB/PHV ratio by using two stages. In the flask experiments, the test of three different single carbon source：glycerol、glucose and sodium acetate, when the glucose is the only single carbon source, the quantity of PHBV output is more and PHV/PHBV ratio is 85%. In the fermentation experiments, with different agitation rate, the higher rate will provide more oxygen. The oxygen transfer rate coefficient (kLa) is from 1.91 to 3.68 hr-1，when the agitation rate is from 100 to 200 rpm. With higher agitation rate, the PHB/PHBV ratio is different from 5% to 99%. And lower agitation rate will make the oxygen transfer down, that the specific growth rate(μ) is decreasing but the PHV/PHBV ratio is increasing. After the agitation rate 200 rpm for 66 hr, the agitation rate was shifted to the agitation rate 100 rpm In two stage different agitation rate. Because the specific growth rate(μ) is fast during agitation rate 200 rpm, it is difficult to look for the suitable shifted point. With prior experience, I started the agitation rate from 150 rpm to 220 rpm. After the agitation rate 150 rpm for 85 hr, the agitation rate was shifted to the agitation rate 220 rpm. Before shifting ,the PHB/PHBV ratio is 0%. After shifting, the PHB/PHBV ratio is decreasing from 17% to 13%. It is higher than PHB/PHBV ratio 5~6% during the single agitation rate 100~150rpm. |
