The research shows that it is possible for bacteria to lie directly on the surface of a metal or mineral and transfer electrical charge through their cell membranes.
“We knew that bacteria can transfer electricity into metals and minerals, and that the interaction depends on proteins on the surface of the bacteria. But it was not been clear whether these proteins do this directly or indirectly though an unknown mediator in the environment,” said lead researcher Dr Tom Clarke.
The team created a simple cell model of the marine bacteria shewanella oneidensis by inserting its proteins into the lipid layers of vesicles – small capsules of lipid membranes such as the ones that make up a bacterial membrane. How well electrons travelled between an electron donor on the inside and an iron-bearing mineral on the outside was measured.
“This is the first time that we have been able to actually look at how the components of a bacterial cell membrane are able to interact with different substances, and understand how differences in metal and mineral interactions can occur on the surface of a cell,” said Clarke. “Our research shows that these proteins can directly touch the mineral surface and produce an electric current, meaning that is possible for the bacteria to lie on the surface of a metal or mineral and conduct electricity through their cell membranes,”
“These bacteria show great potential as microbial fuel cells, where electricity can be generated from the breakdown of domestic or agricultural waste products,” he added.
The team collaborated with researchers at Pacific Northwest National Laboratory.
Findings are published in the journal Proceedings of the National Academy of Sciences (PNAS): Rapid electron exchange between surface-exposed bacterial cytochromes and Fe(III) minerals.