Bacteria can use tiny magnetic particles to effectively create a "natural battery", a new research shows.
The bacteria can load electrons onto and discharge electrons from microscopic particles of magnetite.
This discovery holds the potential of using this mechanism to help clean up environmental pollution and other bioengineering applications.
The flow of electrons is critical to the existence of all life and the fact that magnetite can be considered to be redox-active opens up the possibility of bacteria being able to exist or survive in environments where other redox-active compounds are in short supply in comparison to magnetite.
"In our study we only looked at iron-metabolising bacteria but we speculate that it might be possible for other non-iron-metabolising organisms to use magnetite as a battery as well -- or if they can be made to use it -- through genetic engineering. But this is something that we do not know yet," said study leader James Byrne from the University of Tubingen, Germany.
Researchers from the University of Tubingen, University of Manchester, and the Pacific Northwest National Laboratory, in the US, incubated the soil and water dwelling purple bacteria with magnetite and controlled the amount of light the cultures were exposed to.
Using magnetic, chemical and mineralogical analytical methods, the team showed that in light conditions which replicated day-time, phototrophic iron-oxidising bacteria removed electrons from the magnetite, thereby discharging it.
During night-time conditions, the iron-reducing bacteria took over and were able to dump electrons back onto the magnetite and recharge it for the following cycle, said the study that appeared in the journal Science.
This oxidation/reduction mechanism was repeated over several cycles, meaning that the battery was used over repeated day-night cycles.
"While this work has been on iron-metabolising bacteria, it is thought that in the environment the potential for magnetite to act as a battery could extend to many other types of bacteria which do normally not require iron to grow," the authors noted.
