The development of practical microbial fuel cells took a big step forward this week. Research conducted by a team of scientists from England's University of East Anglia was published on Monday (May 23), in which they revealed that they had discovered "the exact molecular structure of the proteins which enable bacterial cells to transfer electrical charge." Scientists possessing this knowledge can now start working on technology for tethering bacteria directly to electrodes, which could lead to much more efficient microbial fuel cells - also known as bio-batteries.

The team utilized X-ray crystallography to determine the structure of the electron-transferring proteins, which were attached to the surface of a Shewanella oneidensis bacterium cell. X-ray crystallography involves focusing an X-ray onto a crystalline item (such as a protein molecule), then determining its structure by analyzing the angles and intensities of the diffracted beams.

Besides the implications for fuel cell technology, the discovery could also aid in the development of microbe-based agents, used to clean up oil or uranium pollution.

"This is an exciting advance in our understanding of how some bacterial species move electrons from the inside to the outside of a cell," said Dr. Tom Clarke of East Anglia's School of Biological Sciences. "Identifying the precise molecular structure of the key proteins involved in this process is a crucial step towards tapping into microbes as a viable future source of electricity."

Other members of the team included East Anglia's Prof. David Richardson and Prof. Julea Butt, who collaborated with colleagues at the Pacific Northwest National Laboratory in the state of Washington.

Their report appeared in the journal Proceedings of the National Academy of Sciences.