Science and Technology.

E.coli bugs flash like Christmas lights
Posted: Fri Jul 15 2011, 15:57 hrs Washington:


E.coli bacterium creates its own energy and blinks like lights, scientists have discovered. Reuters
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 Escherichia coli, or the E.coli bacterium that lives in the human gut, is an electric creature which creates its own energy and blinks like lights, scientists have discovered.

Researchers at Harvard University devised a way to watch the cells blink on as they spike and then blink off, a phenomenon they believe could help explain how some bacteria resist antibiotics.

While it was already known that the large populations of these cells, on average, tended to maintain a negative charge within their membranes, scientists couldn't tell what the individual cells were up to.

Now, by altering a light-capturing protein found in marine microorganisms and inserting it into the E.coli, the researchers could able for the first time to see single cells change their electrical state, LiveScience reported.

Like other living things, the bugs are capable of creating a difference in electric potential or voltage by pumping charged ions, like sodium and potassium, through their cellular membranes (the outer covering of the cell).

A similar process allows our nerves to send messages within our bodies in the form of electrical spikes, the team reported in the journal Science.

The difference between the electrical charge within the cell's membrane and the outside environment plays an important role in the cell's ability to create energy-storage molecules, driving the motion of its tail, or flagellum, and transporting other molecules through the cellular membrane, study researcher Adam Cohen said.

Originally, the researchers were looking for a way to visualise electrical changes in mammalian cells. They altered the light-capturing protein so it would emit light as the electrical difference changed outside the membrane versus inside the membrane.

"Then one day, (researcher Joel) Kralj was looking at the E.coli in the microscope. He said, 'Holy cow, they are blinking.' And that was not something we expected to find at all," Cohen said.

In fact, the video the researchers captured showed individual cells lighting up for between one and 40 seconds before darkening again. The dark phase, which could last for minutes at a time, is associated with a more negative charge within the cell, Cohen said.

Preliminary research indicates that the blinking may happen as the cell pumps out potential contaminants. This pumping action is a common mechanism of antibiotic resistance, since some bacterial cells will pump out the antibiotics meant to kill them.

So this technique could provide a new way to study antibiotic resistance, Cohen said.

The team also found that the blinking could be altered: For instance, the cells blinked faster when exposed to an acidic environment and slowed down in a more basic environment, stopping altogether when conditions went too far in either direction.

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