Isolation and Analysis of Novel Electrochemically Active Bacteria for Enhanced Power Generation in Microbial Fuel Cells

PROJECT SUMMARY Bacteria capable of exocellular transfer of electrons to solid surfaces, called exoelectrogens, make it possible to obtain electricity from the breakdown of organic matter in microbial fuel cells (MFCs). We obtained several new exoelectrogenic bacteria during this project. We isolated Rhodopseudomonas palustris DX-1, and demonstrated for the first time that a pure culture could produce more power than the mixed culture it was derived from in a high-performance microbial fuel cell (MFC). In contrast, a common iron reducing strain (Geobacter sulfurreducens) produced less power than a mixed culture dominated by the same strain. Using a newly developed U-tube MFC, we isolated Ochrobactrum anthropi YZ-1, which had the remarkable characteristic that it was unable to respire using hydrous Fe(lll) oxide but produced current in an MFC. This further demonstrated that not all exoelectrogens are capable of dissimilatory iron reduction. We obtained for the first time a bacterium (Enterobacter cloaceae) that was capable of simultaneous cellulose degradation and current generation. A strain of the denitrifying bacterium Comamonas denitrificans, isolated from an MFC also produced power showing the importance of some denitrifying bacteria for power generation. We analyzed the microbial communities that developed in MFCs and showed that various operational conditions and materials affect power generation and community structure. These findings demonstrate the importance of various microbial communities in the system for power generation in MFCs.