'Rock-breathing' bacteria could hold key to bio-batteries

“Rock-breathing” bacteria could hold the key to new clean-energy technologies and better ways of cleaning up toxic wastes, according to researchers in the UK.

Scientists at the University of East Anglia (UEA) this week published a study that reveals for the first time the mechanism by which some bacteria survive by “breathing” minerals in oxygen-free regions deep under the Earth’s crust. Their findings could help lead to new microbe-based technologies like fuel cells, “bio-batteries” powered by animal or human waste, and agents to clean up areas contaminated by oil or uranium.

“This is an exciting advance in our understanding of bacterial processes in the Earth’s subsurfaces,” said lead researcher David Richardson of UEA’s School of Biological Sciences. “It will also have important biotechnological impacts. There is potential for these rock-breathing bacteria to be used to clean up environments contaminated with toxic organic pollutants such as oil or radioactive metals such as uranium. Use of these bacteria in microbial fuel-cells powered by sewerage or cow manure is also being explored.”

The vast proportion of the world’s habitable environments is populated by micro-organisms which, unlike humans, can survive without oxygen. Some of these micro-organisms are bacteria that live deep in the Earth’s subsurface and surviving by “breathing rocks,” minerals of iron in particular.

Iron respiration is one of the most common respiratory processes in oxygen-free habitats and therefore has wide environmental significance.

“We discovered that the bacteria can construct tiny biological wires that extend through the cell walls and allow the organism to directly contact, and conduct electrons to, a mineral,” Richardson said. “This means that the bacteria can release electrical charge from inside the cell into the mineral, much like the earth wire on a household plug.”