Big and small, cleaner sources of electricity are just about everywhere. Microbial fuel cells (MFCs) fall at the tinier end of the renewable energy spectrum. MFCs generate electricity from the metabolic activity of bacteria, and according to a new study, they might one day get more power from these little life forms.
Harvard researchers, as discussed last week, are enlisting microbes within dirt to charge cell phones in developing countries. Still, you don't get much bang for your bucket of mud. British biochemists, however, hope to get bigger charges from one tiny bacterium: Shewanella oneidensis.
Through x-ray crystallography, a team from the University of East Anglia zooms in on the bacterium's cell wall to see how electrons pass from the inside to the outside of the cell. Published Monday in the Proceedings of the National Academy of Sciences, descriptions of the precise molecular structures of these protein pathways, might help connect electrodes to the cells more efficiently.
Study author Tom Clarke tells Reuters:
We should be able to use this finding to harvest more electricity from the bacteria. Until now it's been a bit like trying to build a radio when you don't know what type or size of battery you are going to put into it. Now we have a blueprint of what the battery looks like.
All living cells generate electricity during respiration. Cytochromes, or protein "nanowires" within cell membranes, issue excess electrons out of the cell. During anaerobic respiration, S. oneidensis conducts its electrons to metals such as iron and manganese.
Now that they have a better picture of the nanowires, they need to experiment with how well the structures perform. According to Clarke, their research could speed development along for MFCs. Still, years could pass before the bacterium is powering up electronic devices.
Such a device could essentially charge itself anywhere there are nutrients to keep the bacteria fed.
The work for microbes doesn't end there. With some species able to live in environments devoid of oxygen or rich in it, the little guys might be suitable for big jobs like cleaning up pollutants such as oil or radioactive metals like uranium.
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Images: University of East Anglia
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