A fuel cell was used to enrich a microbial consortium generating electricity, using organic wastewater as the fuel. Within 30 days of enrichment the maximum current of 0.2 mA was generated with a resistance of 1 kOhms. Current generation was coupled to a fall in chemical oxygen demand from over 1,700 mg l(-1) down to 50 mg l(-1). Denaturing gradient gel electrophoresis showed a different microbial population in the enriched electrode from that in the sludge used as the inoculum. Electron microscopic observation showed a biofilm on the electrode surface and microbial clumps. Nanobacteria-like particles were present on the biofilm surface. Metabolic inhibitors and electron acceptors inhibited the current generation. 16S ribosomal RNA gene analysis showed a diverse bacterial population in the enrichment culture. These findings demonstrate that an electricity-generating microbial consortium can be enriched using a fuel cell and that the electrochemical activity is a form of anaerobic electron transfer.

Aims:The isolation and identification of a glucose-oxidizing Fe(III)-reducing bacteria (FRB) with electrochemical activity from an anoxic environment, and characterization of the role of Fe(III) in its metabolism. Methods and Results: A Gram-positive (Firmicutes), nonmotile, coccoid and facultative anaerobic FRB was isolated based on its ability to reduce Fe(III). Using the Vitek Gram-positive identification card kit and 16S rRNA gene sequence analysis, the isolate was identified as Enterococcus gallinarum, designated strain MG25. On glucose this isolate produced lactate plus small amounts of acetate, formate and CO 2 and its growth rates were similar in the presence and absence of Fe(O)OH. These results suggest that MG25 can couple glucose oxidation to Fe(III) reduction, but without conservation of energy to support growth. Cyclic voltammetry showed that strain MG25 was electrochemically active. Conclusions: An electrochemically active and FRB, E. gallinarum MG25, was isolated from submerged soil. Fe(III) is used in the bacterial metabolism as an electron sink. Significance and Impact of the Study: This is the first report concerning the electrochemical activity of glucose-oxidizing FRB, E. gallinarum. This organism and others like it could be used as new biocatalysts to improve the performance of a mediator-less microbial fuel cell.

In order to simplify a-Si TFT array manufacturing process, advanced 4 mask process of low resistant metal and new pixel electrode with improved unit process was developed. Slit photolithography with continuous dry etching process on the basis of metal dry etching cleared chronic problems of currently adopted 4 mask process and new combination of material and etchant for wet etching process made it possible to achieve stabilized wet etching and reduce total process steps. Our final version of a-Si TFT process architecture applicable to both notebook and monitor devices, will reinforce competitive power of TFT-LCD by improved displaying performance and ultimate process simplification.

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