Ralstonia eutropha同時脫氮及合成PHB最適培養條件之研究

The Best Cultivation Condition of Denitrification and PHB Synthesis Simultaneously from Medium by Ralstonia Eutropha

黃培銘(Pei-Min Huang)

指導教授 ： 曾四恭

共同指導教授 ： 張志誠

國立臺灣大學/工學院/環境工程學研究所/碩士(2005年)

https://doi.org/10.6342/NTU.2005.00133

摘要

Ralstonia eutropha已證實可在好氧環境下累積大量PHB (poly-3-hydroxybutyrate)，由於PHB可作為生物可分解塑膠的原料，因此本研究主要為探討Ralstonia eutropha在無氧脫硝環境下之生長條件及PHB累積特性，並與好氧的異營生長做比較，期能利用Ralstonia eutropha去除水中之硝酸塩，而脫硝所產生之污泥，由於含有高濃度之PHB，可進一步作為再利用資源，因此具有研究之價值性。
本研究皆以批次方式進行試驗，首先探討Ralstonia eutropha在無硝酸鹽之供氫環境下之生長情形，發現在無氧狀態下，硝酸塩為Ralstonia eutropha之唯一電子接受者，且當碳源不足時，氫氣可提供能量予細胞增殖。而無論在好氧與無氧狀態中，Ralstonia eutropha在生長期即開始合成累積PHB，而在穩定期達到最高濃度，進入內呼吸期後，菌體內之PHB即隨著菌體分解而降低含量。
在無氧狀態下，分別以不同C/N(5、10、20、25及30)、氨氮濃度(100及200 mgNH4-N/L)及硝酸鹽濃度(292、397及485 mgNO3-N/L)探討Ralstonia eutropha對PHB合成累積之影響，結果顯示在C/N<20時，有機物對PHB合成累積影響較顯著，且氨氮濃度越高，對於微生物生長速率及PHB之合成累積都有明顯提升，而較高之硝酸塩濃度，亦會提高PHB之合成累積量。
在好氧狀態方面，亦探討不同C/N對Ralstonia eutropha合成累積PHB之影響，發現此因子影響情形與無氧狀態類似，惟好氧狀態因生長速率較快，菌液增殖濃度較高，其在各個階段之PHB之合成累積量，皆高於無氧狀態。

關鍵字

PHB ； Ralstonia eutropha ； 脫硝

並列摘要

It was verified that Ralstonia eutropha could accumulate a large amount of PHB in cells under the aerobic condition, and PHB is the raw material of plastic which can be decomposed by bacteria. So the aim of this study is to find out the growth condition and characteristic of PHB accumulation by Ralstonia eutropha in anoxic state, and then compare it with living under the aerobic and heterotrophic condition. It’s expected that Ralstonia eutropha can remove the nitrate from the waste water and the sludge which possesses high concentrated PHB can be reused. According to the reason above it’s worthy to do this research.
All experiments proceeded in batch reactor. First of all, we provide hydrogen and discuss the growth of Ralstonia eutropha in anoxic condition without nitrate. And then we find out that nitrate is the only electronic acceptor of Ralstonia eutropha in anoxic condition. In that condition hydrogen can be the energy source of Ralstonia eutropha to promote the growth when the carbon lacks in the liquid. In both anoxic and aerobic conditions, Ralstonia eutropha begins to accumulate PHB in growth phase. Furthermore, reaching the highest content of PHB in cells is in the stationary phase. And then declining the PHB content in cells accompanys the coming of endogenous phase.
In anoxic condition, i also researched PHB accumulation by Ralstonia eutropha in different C/N(5.10.20.25 and 30)、ammonia concentration(100 and 200 mgNH4-N/L) and nitrate concentration(292、397 and 485 mgNO3-N/L). The result reveals the difference of PHB accumulation in cells is obvious under C/N<20. The higher concentration of ammonia will accelerate the growth of Ralstonia eutropha and promote the PHB accumulation in cells apparently. There is also influence of enhancing the PHB accumulation in cells as the concentration of nitrate is promoting.
In the aspect of aerobic condition, the different C/N against the influence of PHB accumulation by Ralstonia eutropha was performed. It was found that the condition of aerobic is similar to anoxic condition. The most important difference between the two conditions is that the PHB accumulation in aerobic condition is higher than that in anoxic condition. Maybe it is the faster growth and higher microorganism concentration that leads to the outcome.

並列關鍵字

Denitrification ； PHB ； Ralstonia eutropha

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