Researchers discover living power cables
25 Oct 2012
Scientists have uncovered bacteria that function as living power cables to transmit electrons thousands of cell lengths away.
The Desulfobulbus bacterial cells, which are only a few thousandths of a millimeter long each, form a multicellular filament that can transmit electrons across a distance of up to 1cm.
“To move electrons over these enormous distances in an entirely biological system would have been thought impossible,” said Moh El-Naggar, assistant professor of physics at the USC Dornsife College.
Aarhus scientists had discovered a seemingly inexplicable electric current on the sea floor years ago.
Physicists are increasingly being tapped to tackle tough biological questions
The new experiments revealed that these currents are mediated by a hitherto unknown type of long, multicellular bacteria that act as living power cables.
“Until we found the cables, we imagined something cooperative where electrons were transported through external networks between different bacteria,” said Lars Peter Nielsen of the Aarhus Department of Bioscience and a corresponding author of the paper.
“It was indeed a surprise to realise that it was all going on inside a single organism.”
The team studied bacteria living in marine sediments that power themselves by oxidising hydrogen sulfide.
Cells at the bottom live in a zone that is poor in oxygen but rich in hydrogen sulfide, and those at the top live in an area rich in oxygen but poor in hydrogen sulfide.
As a result, they form long chains that transport individual electrons from the bottom to the top, completing the chemical reaction and generating life-sustaining energy.
“You have feeder cells on one end and breather cells on the other, allowing the whole living cable to survive,” El-Naggar said.
Aarhus and USC researchers collaborated to use physical techniques to evaluate the long-distance electron transfer in the filamentous bacteria.
El-Naggar and his colleagues had previously used scanning-probe microscopy and nanofabrication methods to describe how bacteria use nanoscale structures called “bacterial nanowires” to transmit electrons many body lengths away from cells.
“I’m a physicist, so when I look at remarkable phenomena like this, I like to put it into a quantifiable process,” said El-Naggar. He noted that physicists are increasingly being tapped to tackle tough biological questions
“This world is so fertile right now,” he said. “It’s just exploding.”
The research was funded by the European Research Council, the Danish National Research Foundation, the Danish Council for Independent Research and the Max Planck Society.
