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標題: 純菌株對多環芳香族碳氫化合物生物降解之動力參數探討
A study for kinetic parameters of biodegradation of PAHs by pure cultures
作者: 鄭光勛
Cheng, Kuang-Hsun
關鍵字: Naphthalene;萘;respirometer;respirometric two-phase method;氣泡式呼吸儀;二相動力模式求解
出版社: 環境工程學系
摘 要
根據前期研究結果顯示,實驗室所分離之純菌株 Rhodococcus rubber N4 在萘過飽和含顆粒性萘時,對於顆粒性萘有顯著降解現象,文獻亦指出此菌株具有產生生物界面活性劑之能力。因此,利用表面張力、乳化指數與細胞疏水性試驗,探討生物界面活性劑與顆粒性萘降解的關係。並藉由氣泡式呼吸儀與兩相動力模式,測定Monod 之動力參數(Ks, Yg, μmax and kd),由生物動力參數的求解,了解不同條件下各菌株的降解情形。
實驗結果顯示,R. rubber N4 對高濃度甚至是顆粒性萘有較快的降解,實驗所用之其他菌株則會因高濃度而被抑制,呈現較長的遲滯期。比較各菌株於不同基質增殖所作之表面張力及乳化試驗, R. rubber N4 並沒有顯著表現,而 Serratia marcescens N5 具有生物界面活性劑產生的能力,但對於萘的降解並沒有太大的幫助。在氣泡式呼吸儀兩相動力模式求解方面,各菌株在馴化之後,遲滯期顯著縮短,對萘的生物可降解率提高,但仍可觀察到顆粒性萘對菌的抑制現象。P. rhodesiae N2馴化後Yg值增加,R. rubber N4馴化後Yg值降低,卻有更高的生物可降解率,在長期馴化之後對萘有更強及更穩定的降解能力,更進一步再由攝氧率與累積攝氧圖的變化,發現R. ruber N4降解萘的獨特指紋圖譜。由Yg 值求解與實際Y測值的高相關性(Yg=1.25Y, r2=0.95),證實二相動力模式規劃求解具有一定的可行性及可信度。由實驗數據及數值的迴歸分析,證實Ks值確會隨著S0值變動。在R. rubber N4中間產物的監測,偵測到龍膽酸的生成,並且能進一步的降解。

According to our preoious studies, the Rhodococcus rubber N4, which cultured in the Naphthalene's oversaturated aqueous with unsoluble Naphthalene, could be biodegraded the unsoluble Naphthalene. Some of the scientific literature has shown that R. rubber could produce biosurfactant. By monitoring the surface tension, emulsification index and cellular hydrophobicity, we could probe into the relationship between producing biosurfactant and biodegrading unsoluble Naphthalene, and to determine the four Monod kinetic parameters(Ks, Yg, μmax and kd) through the use of respirometric-two phase method.
The results indicated that in Naphthalene's oversaturated aqueous with unsoluble Naphthalene, R. rubber N4 had shorter arrearage period and greater degrading than other pure cultures. Comparing the results of surface tension and emulsification index culturing in different mediums, we infer that producing biosurfactant was not a main factor in degrading Naphthalene by pure cultures. Getting the Monod kinetic parameters by respirometric two-phase method we found that the acclimated strains had shorter arrearage period and power in degrading Naphthalene, and specifically in R. rubber N4 after an over long period of incubaction (90 days) that we observed the microbial fingerprint graph in its Naphthalene-degrading from the variation in OUR vs. Ou graph. At high correlation between the actual Yield and getting Yg from the respirometric two-phase method(Yg=1.25Yield, r2=0.95),we confirmed that the method should be a trusty and feasibility one.
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