Breakthrough in Electricity-Producing Microbe

University of Massachusetts researchers have made a breakthrough with "Geobacter," a microbe that produces electric current from mud and wastewater. A conservative estimate puts the energy output increase at eight times that of the original organism, potentially allowing applications far beyond that of extracting electricity from mud. "Now, planning can move forward to design microbial fuel cells that convert waste water and renewable biomass to electricity, treat a single home's waste while producing localized power (especially attractive in developing countries), power mobile electronics, vehicles and implanted medical devices, and drive bioremediation of contaminated environments."

Comments

Re:I, for one...

[reverseengineer]

Well, this bacterium was originally discovered feeding off the muck at the bottom of the Potomac River. Make of that what you will....

Re:Details from the published paper

[reverseengineer]

Here's the abstract from the paper (with some line breaks inserted for readability):

Geobacter sulfurreducens produces current densities in microbial fuel cells that are among the highest known for pure cultures. The possibility of adapting this organism to produce even higher current densities was evaluated. A system in which a graphite anode was poised at 400 mV (versus Ag/AgCl) was inoculated with the wild-type strain of G. sulfurreducens, strain DL-1. An isolate, designated strain KN400, was recovered from the biofilm after 5 months of growth on the electrode. KN400 was much more effective in current production than strain DL-1. This was apparent with anodes poised at 400 mV, as well as in systems run in true fuel cell mode. KN400 had current (7.6 A/m2) and power (3.9 W/m2) densities that respectively were substantially higher than those of DL1 (1.4 A/m2 and 0.5 W/m2).

On a per cell basis KN400 was more effective in current production than DL1, requiring thinner biofilms to make equivalent current. The enhanced capacity for current production in KN400 was associated with a greater abundance of electrically conductive microbial nanowires than DL1 and lower internal resistance (0.015 versus 0.130 /m2) and mass transfer limitation in KN400 fuel cells. KN400 produced flagella, whereas DL1 does not. Surprisingly, KN400 had much less outer-surface c-type cytochromes than DL1. KN400 also had a greater propensity to form biofilms on glass or graphite than DL1, even when growing with the soluble electron acceptor, fumarate.

These results demonstrate that it is possible to enhance the ability of microorganisms to electrochemically interact with electrodes with the appropriate selective pressure and that improved current production is associated with clear differences in the properties of the outer surface of the cell that may provide insights into the mechanisms for microbe-electrode interactions.

Photos

[anukit]

Some technical info and photos: http://www.geobacter.org/publications/19487117/