Study finds bacteria’s proteins can directly “touch” mineral or metal surfaces to produce an electric current
Scientists from the University of East Anglia claimed today to have made a significant discovery that could lead to efficient generation of clean electricity from bacteria and therefore “bio-batteries”
Proteins on the surface of bacteria can produce an electrical current by touching a mineral surface, according to the research, published in the journal Proceedings of the National Academy of Sciences (PNAS).
Just by lying on the surface of a metal or mineral, bacteria can transfer electrical charge through their cell membranes, meaning they could be used, if hooked up to electrodes, as “microbial fuel cells”, otherwise known as bio-batteries.
“We knew that bacteria can transfer electricity into metals and minerals, and that the interaction depends on special proteins on the surface of the bacteria,” said lead researcher Dr Tom Clarke, from UEA’s school of Biological Sciences
“But it has not been clear whether these proteins do this directly or indirectly through an unknown mediator in the environment.
“Our research shows that these proteins can directly ‘touch’ the mineral surface and produce an electric current.”
The researchers looked at a specific marine bacteria called Shewanella oneidensis, of which they created a synthetic version.
They inserted the bacteria’s proteins thought to be effective at transferring electrons into small capsules of lipid membranes, designed to imitate those that make up a bacterial membrane.
They tested how well electrons travelled between the proteins on the inside and an iron-bearing mineral on the outside.
As well as having potential for batteries, the findings could have other environmental benefits, in providing greater understanding of how carbon interacts with the atmosphere and other substances around it, added biochemist Liang Shi of Pacific Northwest National Laboratory, which also contributed to the study.
“When organic matter is involved in reducing iron, it releases carbon dioxide and water,” said Liang Shi. “And when iron is used as an energy source, bacteria incorporate carbon dioxide into food. If we understand electron transfer, we can learn how bacteria controls the carbon cycle.”
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