微生物燃料電池之生物陽極/陰極菌種分離及其產電機制探討

Abstract

微生物燃料電池由於本身具有廢水處理同時可進行能源回收等特性，近年來逐漸受到眾人矚目。反應槽體構造及電極材料之研究日趨成熟，以及近年來分子生物學等研究技術之突破，開始逐漸有科學家將研究重心轉往催化整個系統反應之核心：陽極與陰極之微生物反應機制探討。在陽極端，菌株具有將胞內電子傳遞至外部電極之能力，此種代謝途徑又稱之為胞外產電呼吸；在陰極端，菌株具有加速催化氧氣還原之能力，然而目前卻鮮少有研究針對單一純菌之陰極反應測試。 本研究核心理念在於針對兩極菌株特有之能力進行馴養、純化、分離，再對於分離之菌株進行檢測。陽極端透過菌株還原鐵之能力進行篩選，陰極端透過菌株是否具有提高整體微生物燃料電池之能力進行判別，經由兩極菌株能力篩選之有力菌株會進一步利用循環伏安法、交流阻抗分析及系統功率密度測試菌株之產電機制及往後運用之可行性。 成果顯示，本研究所設計之實驗規劃可提供快速且直觀之檢測結果，陽極試驗中除了以Geobacter sulfurreducens作為對照組，更發現了一株新的產電菌株Macellibacteroides fermentans；陰極試驗除了設計出一套全新檢測菌株陰極反應流程，更發現了一株Stenotrophomonas maltophilia除了具有陽極特性，更具有可以於白金電極相比擬之能力。最後期許能將此套技術流程加以精進簡化，並且廣泛推廣，以利後人能更加完善分析微生物燃料電池之菌群結構及菌株電化學活性。

Microbial fuel cell (MFC) primarily consists of anode, cathode, and membrane. To minimize the internal resistance and thus improve the MFC performances, abiotic stretagies such as coating effective catalysts on the anode and cathode have been thoroughly investigated. However, the microbial mechanisms of anodic/cathodic current generation were emphasized more in the present studies. For the anode, bacteria utilizing electron transfer pathway is called “exoelectrogens” or “anodophiles”, which were considerablely studied using two model mocrooganisms: Geobacter sp. and Shewanella sp. in the past studies. However, some other bacteria which can also utilize this pathway are successively found and isolated in many studies. In addition, the idea of bacterial catalysts is attractive due to the consideration of low cost and high efficiency. Accordingly, this study focuses on the microbial communities and isolates on the bio-anode and bio-cathode that were respectively inuculated with the mixed cultures obtained from the Hsinchu rice field and Dihua sewage treatment plant. Besides, to examine the ferric-citrate- and amorphous-iron reducing capabilities of anodic microorganisms and the oxygen-reduction enhancement by cathodic microorganisms, the current-generating mechanisms were directly observed in the MFCs by reading the results of power density curves, electrochemical impedance spectroscopy, and cyclic voltammetry. In this research, Macellibacteroides fermentans was isolates to be a new exoelectrogens from bio-anode. Stenotrophomonas maltophilia is the most effective microorganisms assisting cathodic process from oxygen reduction, but no significant electrochemical activity of it was detected. By selectively amending powerful bacteria on the anode and cathode, a better MFC performance can be anticipated in the future.