异化铁还原梭菌Clostridium bifermentans EZ-1产氢与电化学特性

Hydrogen-producing and electrochemical properties of a dissimilatory Fe(III) reducer Clostridium bifermentans EZ-1

摘要:

[目的]从黄河三角洲滨海湿地土壤中获得同时具备产氢、产电以及异化铁还原能力的多功能菌株。[方法]通过厌氧分离技术从黄河三角洲土壤中分离得到纯菌株，16S rRNA基因测序后与数据库已有序列进行比对。利用革兰氏染色及扫描电镜观察菌株形态，并用气相色谱（gas chromatography，GC）和液相色谱（high performance liquid chromatography，HPLC）检测其生理代谢底物和产物。通过添加不同形态铁氧化物检测该菌株Fe（Ⅲ）的还原能力。构建微生物燃料电池（Microbial fuel cells，MFCs）检测该菌株的电化学活性。[结果]16S rRNA基因序列比对发现其与双酶梭菌Clostridium bifermentans的相似性达97.99%。革兰氏染色结果显示为阳性菌。能够利用葡萄糖为底物发酵产生氢气、二氧化碳、乙酸和丁酸。Fe（Ⅲ）还原能力检测发现，其不仅可以还原柠檬酸铁（FeC₆H₅O₇）中可溶性的Fe（Ⅲ），还可以还原无定形铁水铁矿（FeOOH）和晶型纳米磁铁矿（Fe₃O₄）中的Fe（Ⅲ）。此外，经MFCs检测发现，该菌具有电化学活性，最大电流输出密度可达6.5 mA/m²，且在0.15 V位置存在氧化峰。[结论]本研究从土壤中成功分离得到了一株同时具有产氢、产电以及异化铁还原能力的多功能梭菌菌株，保藏并命名为Clostridium bifermentans EZ-1。

Abstract:

[Objective] To obtain and characterize a versatile strain isolated from the soil of Yellow River Delta. [Methods] The strain was isolated by anaerobic technologies and identified by sequencing the 16S rRNA gene. The morphology was depicted with Gram staining and scanning electron microscope. High performance liquid chromatography and gas chromatography were used to analyze the metabolic substrates and productions. Ferric citrate (FeC₆H₅O₇), ferrihydrite (FeOOH) and magnetite (Fe₃O₄) were supplied to detect the capability of Fe(Ⅲ) reduction of this strain. Microbial fuel cells were constructed with graphite as electrodes to test the electrochemical activity of this strain. [Results] Compared to Clostridium bifermentans, the similarity of 16S rRNA gene is 97.99%. It is a rod, Gram-positive bacterium, which can use glucose to produce hydrogen, carbon dioxide, acetate and butyrate. The Fe(Ⅲ) reduction results showed that it could reduce soluble ferric citrate, amorphous ferrihydrite and crystal magnetite. Furthermore, the electrochemical activity was detected and the maximum current density peaked at 6.5 mA/m². [Conclusion] In this work, a versatile strain which is capable of producing hydrogen, electricity and reducing iron oxide, was successfully isolated from the soil of Yellow River Delta named as Clostridium bifermentans EZ-1.