Wednesday, October 31, 2012

SCIENCE/ENERGY SPECIAL....Bacteria that is just like electrical cables



Bacteria that is just like electrical cables 

Danish scientists have discovered how some bacteria form gigantic power lines to survive in the seabed. The find might lead to new types of electronic devices 

    Researchers at Aarhus University, Denmark, made a discovery almost three years ago when they measured electric currents in the seabed. It was unclear as to what was conducting the current, but the researchers imagined the electric currents might run between different bacteria via a joint external wiring network. They have now solved the mystery. It turns out that the whole process takes place inside bacteria that are just one centimetre long. They make up a kind of live electric cablethatnoonehadeverimaginedexisted. Each one of these ‘cable bacteria’ contains a bundle of insulated wires that conduct an electric current from one end to the other.
    “Our experiments showed that the electricconnectionsintheseabedmust be solid structures built by bacteria,” says Aarhus student Christian Pfeffer.
    Under the microscope, they found an unknown type of long, bacteria that always seemed to be there when they measured the electric currents.
    “Theideathatthesebacteriashould be electric cables really fell into place when, we saw wire-like strings enclosed by a membrane inside the bacteria,” says Nils Risgaard-Petersen, Aarhus University.
KILOMETERS OF LIVING CABLES
The bacterium is one hundred times thinner than a hair and the whole bacterium functions as an electric cable withanumberofinsulatedwireswithinit.Quitesimilartotheelectriccables we know from our daily lives.
    “Such unique insulated biological wires seem simple but with incredible complexity at nanoscale,” says student Jie Song, who mapped the bacteria’s electrical properties.
    In an undisturbed seabed more than tens of thousands kilometers cable bacteria live under a single square meter seabed. The ability to conduct an electric current gives the bacteria ability to grab a lot of energy from decomposition processes in the seabed.
    Unlike all other known forms of life, cable bacteria maintain an efficient combustion down in the oxygen-free part of the seabed. It only requires that one end to reach the oxygen which the seawater provides to the top of the seabed. The combustion is a transfer of the electrons of the food to oxygen which the bacterial inner wires manage over centimeter-long distances.However,smalldisturbances can lead to fatal “cable breakage” in the fragile bacteria.
    “On the one hand, it is still very unreal and fantastic. On the other hand, it is also very tangible,” says Professor Lars Peter Nielsen. In the future the researchers hope to use this biological evolution to create new types of electronics.
MM121026

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