| 摘要: | 三氯乙烯(TCE)為常見地下水污染物，其生物修復常仰賴脫鹵球菌(Dehalococcoides mccartyi)進行還原脫氯。然而，場址經化學整治後容易伴隨副產物乙炔(C₂H₂)累積，進一步造成抑制脫鹵球菌進行脫氯，對整治形成負面影響。儘管生物刺激策略可藉由外加碳源、氮源與電子供體促進微生物生長，但過度添加藥劑將會影響脫氯活性，亦提高整治成本。因此，本研究提出新共培養策略，結合乙炔代謝與固氮能力兼具之 Syntrophotalea acetylenivorans SFB93，得以利用乙炔水解酶將乙炔轉換為碳源醋酸及氫氣同時經由nitrogenase產生氮源，嘗試解決乙炔抑制並且同時提供脫氯所需營養源。實驗結果顯示，D. mccartyi strain FL2在乙炔存在下維持部分活性，而 CWV2 則表現出較高的敏感性。RT-qPCR 分析進一步指出，乙炔抑制 FL2 之脫氯基因 tceA 表現，顯示不同D. mccartyi 菌株對乙炔的反應存在明顯差異。我們透過乙炔還原法與 RT-qPCR分析觀察到， SFB93在TCE 存在下能維持穩定消耗乙炔產生碳源醋酸及氫氣並表現固氮基因 nifHDK，進一步於乙炔共污染與缺乏營養鹽條件下建構共培養系統，結果顯示，即便未添加D. mccartyi所需之營養源經由共培養系統，SFB93仍能消耗乙炔並提供碳源醋酸、氫氣及氮源，使 FL2 維持脫氯功能，證實共培養系統可有效解決乙炔抑制與營養鹽的缺乏之問題。本研究彰顯了不同脫氯菌株對乙炔敏感性之顯著差異，並首度整合乙炔代謝與碳、氫、氮三項營養來源供給功能於共培養系統中，有效提升 D. mccartyi 在乙炔共污染且營養匱乏環境下之存活與脫氯效能，為地下水整治策略提供一項具經濟效益的新選擇。;Trichloroethene (TCE) is a prevalent groundwater contaminant whose bioremediation commonly relies on reductive dechlorination by Dehalococcoides mccartyi. However, chemical remediation often leads to acetylene (C₂H₂) accumulation, which inhibits D. mccartyi activity and compromises treatment efficacy. Although biostimulation with carbon, nitrogen, and electron donors can promote microbial growth, excessive amendment may suppress dechlorination and increase costs. To address these challenges, this study proposed a novel coculture strategy using Syntrophotalea acetylenivorans SFB93, which was capable of both acetylene metabolism and nitrogen fixation. SFB93 converted acetylene into acetate and hydrogen via acetylene hydratase and supplied fixed nitrogen via nitrogenase, collectively providing essential nutrients for D. mccartyi-mediated dechlorination. Experimental results showed that D. mccartyi strain FL2 maintained partial dechlorination activity under acetylene stress, while D. mccartyi strain CWV2 was more sensitive. RT-qPCR revealed acetylene suppressed tceA expression in FL2, indicating strain-specific responses. In the presence of TCE, SFB93 consistently consumed acetylene, expressed nifHDK genes, and supported FL2 dechlorination under nutrient-deficient conditions without external nitrogen. This study revealed significant differences in acetylene sensitivity among D. mccartyi strains and, for the first time, integrated acetylene metabolism with the simultaneous provision of carbon, hydrogen, and nitrogen in a single coculture system. The results demonstrated enhanced survival and dechlorination performance of D. mccartyi under acetylene-stressed and nutrient-deficient conditions, offering a cost-effective strategy for groundwater bioremediation. |
