An obligatory anaerobic bacterium was isolated from a mediator-less microbial fuel cell using starch processing wastewater as the fuel and designated as EG3. The isolate was Gram-positive, motile and rod (2.8-3.0 μm long, 0.5-0.6 μm wide). The partial 16S rRNA gene sequence and analysis of the cellular fatty acids profile suggested that EG3 clusters with Clostridium sub-phylum and exhibited the highest similarity (98%) with Clostridium butyricum. The temperature and pH optimum for growth were 37°C and 7.0, respectively. The major products of glucose and glucose/Fe(O)OH metabolism were lactate, formate, butyrate, acetate, CO2 and H2. Growth was faster at the initial phase and the cell yield was higher when the medium was supplemented with Fe(O)OH than without Fe(O)OH. These results suggest that Fe(III) ion is utilised as an electron sink. Cyclic voltammetry showed that Clostridium butyricum EG3 cells were electrochemically active. It is a novel characteristic of strict anaerobic Gram-positive bacteria.
Bibliographical noteFunding Information:
We are deeply grateful to Professor Julian Wimpenny, Mr Michael Turner and Mr Chang-Suk Lee for their assistance in electron microscopy. This work was supported by the Ministry of Science and Technology, Korea (Grant No. 99-N1-01-01-A-03 and 00-J-BP-B-03).
- Clostridium sp. EG3
- Cyclic voltammogram
- Dissimilatory Fe(III) reduction
- Electrochemically active bacteria
- Microbial fuel cell
ASJC Scopus subject areas
- Infectious Diseases