利用异化金属还原菌构建含糖微生物燃料电池

环境中的一些微生物通过还原金属氧化物进行无氧呼吸,而石墨电极与金属氧化物相似,也可以作为这类微生物呼吸作用的最终电子受体,利用这类微生物构建微生物燃料电池,以糖类物质为燃料,对电池产电情况、产电原理进行研究。实验结果表明,以Rhodoferaxferrireducens为产电微生物,在外接电阻510Ω条件下,以葡萄糖为燃料,常温下产生的电流密度达158mAm2(平台电压为0.46V,电极有效接触表面积为57cm2),且循环性能良好。更换燃料为其它糖,发现微生物可以利用多种糖进行产电;通过SEM观察发现大量微生物吸附在石墨电极上,用Bradford法对运行20d后电池的细胞量进行定量,测得悬浮细胞蛋白浓度为140mgL,吸附在电极上的生物量为1180mgm2。通过数据采集分析和细菌还原实验,发现吸附在电极上的微生物对电压的产生贡献最大,具有电化学和生物学活性;悬浮细胞对产电贡献很小,不具有电化学和生物学活性。

Construction of Sugar-based Microbial Fuel Cells by Dissimilatory Metal Reduction Bacteria

Dissimilatory Metal Reduction Bacteria play an important role in the anaerobic environment. This kind of bacteria gains energy by coupling the oxidation of organic acid or sugars to the reduction of metal oxides. The graphite electrode rode can also be used as the final electron acceptor due to its similarity to solid metal oxides. Based on this biological mechanism, Dissimilatory Metal Reduction Bacteria Rhodoferaxferrireducens was used to construct a suit of microbial fuel cells with sugars as fuel, and the process and mechanism of electricity generation was studied. Rhodoferax ferrireducens was inoculated into the anode chamber in which a graphite electrode served as the final electron acceptor and glucose as the sole electron donor. It was showed that current density was up to 158mA/m2 with the resistance of 510omega at the normal temperature (platform voltage was around 0.46V, the effectual electrode surface was 57cm2). Following 20days' growth a large amount of bacteria cells attached to the electrode surface had been observed through the SEM images. The plandtonic cell protein concentration was 140mg/L and the attached biomass of electrode surface was 1180mg/m2 determined by the Bradford method, which indicated quite a few bacteria attached to the electrode. By analyzing the voltage value measured by the data acquisition system, it was proved that microbial electricity generation attributed mainly to the electrochemically and biologically active cells attached to the electrode, while the planktonic cells had no ability to catalyze electricity generation and almost had not electrochemically and biologically active. Furthermore, this kind of microbial fuel cells exhibited a good electrochemical cycle property and proved to be efficient in biomass utilization and energy restore since other sugars like fructose, sucrose, even xylose, could be oxidized and finally decomposed. Vast waste biomass in the form of carbohydrates is discarded in the environment. Not only is contamination of the environment caused by the discarded biomass, but also abundant energy stored in the biomass is drained away in vain. The sugar-based microbial fuel cells constructed by Rhodoferax ferrireducens could effectively transform the energy stored in sugars into electricity. Meanwhile, the microbial fuel cells presented in this paper, which could work cleanly at normal temperature with a good cycle property, showed a promising future application in this field.