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Scientists decipher bacteria motor

New Australian research may help stop bacterial infection in its tracks, thanks to the first clear understanding of how the miniscule motors driving bacteria operate.

For 30 years scientists have been trying to determine what mechanisms are behind the tiny incredibly energy-efficient flagellar motors in bacteria.

These nano-size biological machines enable the single cell organisms to manoeuvre swiftly towards nutrients and away from toxins.

A group at Sydney's Victor Chang Cardiac Research Institute have now been able to explain the workings of the flagellar motor for the first time, with their findings published in the latest online edition of Nature.

The research provides a potentially game-changing new method for fighting increasingly antibiotic-resistant bacterial infections such as salmonella, rheumatic fever and staphylococcus.

Atomic elegance

The motors that drive bacteria were first observed in the 1970s and are currently the most efficient rotary motor known, able to convert between 99% and 100% of their fuel energy into rotational power.

This contrasts with the maximum energy efficiency of mechanical motors, for example, the engine of a Formula 1 racing car, which converts just 37%.

Drawing on work done by previous research groups and using x-ray crystallography, which can see particles at an atomic level, the Australian researchers created a precise 3D-image of the biological machine over a period of two years.

Dr Lawrence Lee, one of those leading the Victor Chang research group, says the result surprised him and his colleagues, in that it bore a very close resemblance to an electric engine, using positive and negative charges to drive its rotation.

"You can see the way nature has pieced this together and it's really quite elegant and beautiful to look at," says Lee.

Importantly, Lee and his colleagues were also able to discern how the agile organisms can switch from forward to reverse almost instantaneously by swapping the electric charge within the motor.

New antibacterial arsenal

The most obvious potential application of the new findings is in the medical field, where putting the brakes on bacteria could potentially help stop serious infections.

"The idea is if you can stop the motor from working then you can have an effective antibacterial without side-effects because you're specifically targeting something that only exists in bacteria," says Lee.

The Victor Chang group is now working with researchers at England's Oxford University to devise such mechanisms that could one day be used as common medicines.

But when it comes to the possibility of creating a flagellar-style motor for the Formula 1 circuit, Lee cautions that it's unlikely to happen any time soon.

He says there is still so much to learn about how the forces are operating at the minuscule level before there's any chance of it being effectively up-scaled.