共營(Syntrophy)是兩種或兩種以上不同的微生物彼此依賴克服特殊化合物之熱力學障礙(Thermodynamically barrier)，以獲得生長能量的一種微生物生態關係。在共營關係中，共營菌分解基質產生的過量電子會透過氫和甲酸之類的電子載體擴散到相鄰的微生物細胞中，這種透過電子載體在細胞間間接傳遞電子的方式稱為種間間接電子傳遞(Indirect Interspecies Electron Transfer, IIET)。電子也可以透過導電性纖毛和細胞膜上細胞色素在微生物間直接傳遞，稱為種間直接電子傳遞(Direct Interspecies Electron Transfer, DIET)。直接電子傳遞被認為有促進共營分解並在厭氧消化過程中提高甲烷產量的潛力。導電材料如活性碳和磁鐵礦的提供了DIET的另一種電子直接傳遞途徑，微生物附著到導電材料表面，直接透過導電性材料進行電子轉移。在厭氧分解乙酸、丙酸、丁酸和乙醇等小分子化合物的微生物群中，種間直接電子傳遞已經被證實，然而此機制是否存在於較複雜的苯環化合物的降解中仍不清楚。對苯二甲酸是製造聚酯纖維的原料，在工業製程中會產生大量含對苯二甲酸的廢水，雖然屬於生物難分解的苯環類化合物，厭氧微生物仍可以透過共營方式分解對苯二甲酸，產生甲烷與二氧化碳。為了探討導電材性材料是否影響對苯二甲酸厭氧降解，本研究使用16S rRNA 基因擴增子定序和蛋白質體學方法，分別探討批次實驗及厭氧反應槽在添加導電性材料前後的菌項與菌群活性變化。在批次實驗中，添加磁鐵礦的組別展現較好的產甲烷效率，並且促進不同的共營族群，如uncultured Chloroflexi phylum 和 Methanothermobacter species 生長，這和控制組的Syntrophorhabdus and Methanosaeta 是不一樣的。反應槽的產甲烷表現也在用含磁鐵礦的泡棉置換槽中一半的泡棉後提升。嗜氫型甲烷菌Methanolinea在有磁鐵礦的泡棉中組成比例提升。分析蛋白表現的結果顯示，產甲烷量提升可能是因為在沒有添加磁鐵礦泡棉中Methanosaeta及有添加磁鐵礦泡棉中Methanolinea and Syntrophorhabdus基因表現向上調節的結果。此結果顯示，磁鐵礦可能會改變厭氧對苯二甲酸共營降解時的路徑，從原本由對苯二甲酸→乙酸→甲烷的路徑轉變為對苯二甲酸→乙酸→氫氣+二氧化碳→甲烷。本研究提供一個導電材料影響芳香族化合物厭氧生物分解的結果。

Syntrophy is a microbial relationship that two or more than two kinds of microorganisms work together to overcome the thermodynamical barrier during anaerobic degradation of a specific substrate for energy conservation. In the syntrophic process, the excess electrons produced by syntrophic microorganisms are transferred to the adjacent partners indirectly through the electron shuttle-like hydrogen and formate, called indirect interspecies electron transfer (IIET), or directly by the conductive pilin and membrane-bound cytochrome. The latter is called direct interspecies electron transfer (DIET), which may stimulate the syntrophic degradation process to enhance the methane yield potentially during anaerobic digestion. Conductive materials like activated carbon and magnetite potential provide an alternative pathway of DIET, in which the electrons are directly transferred when microorganisms adhere to the surface of conductive materials. DIET has been demonstrated with the anaerobic consortia in degrading small compounds like volatile fatty acids (acetate, propionate, and butyrate) and ethanol, but whether the underlying rationale works with aromatic compounds still remains unclear. Terephthalate acid (TA) is the raw material in the manufacturing of various plastic products. The TA-containing wastewater has been conventionally treated by the anaerobic biological treatment. Although TA is recalcitrant to anaerobes, it could be degraded into methane by the network of syntrophic consortia. To elucidate the metabolism of anaerobic TA degradation with conductive materials, the batch, and continuous reactor operation experiments were conducted, while the syntrophic consortia with and without magnetite were analyzed using a 16S rRNA gene amplicon sequencing and proteomics approach. In the batch experiment, the treatment with magnetite had a better methane production ability with facilitated growth of different syntrophic partners, like uncultured Chloroflexi populations and Methanothermobacter species as compared with the control group with the dominance of TA degrading, Syntrophorhabdus and acetotrophic Methanosaeta. The methane-producing ability of bioreactor was also promoted in the company with the increased abundance of the hydrogenotrophic methanogen – Methanolinea in responding to the replacement of sponge cubes in the reactor with the sponge embedded magnetite particles. The proteomics results revealed that the enhancement of the methane-production from the reactor might be attributed to the upregulated gene expression of Methanosaeta in the sponge without magnetite and Methanolinea and Syntrophorhabdus in sponge with magnetite. This study reveals that the magnetite might change the metabolic route of TA degradation from TA → acetate → methane to another pathway of TA → acetate → H2 + CO2 →methane. This study provides an insight into the effect of the conductive materials on the anaerobic degradation of an aromatic compound.

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