Their power could be harnessed in future devices

Dec 17, 2009 10:43 GMT  ·  By
Even common bacteria can turn spoked wheels millions of times their size, when placed in a liquid solution
   Even common bacteria can turn spoked wheels millions of times their size, when placed in a liquid solution

Scientists have learned that microorganisms such as bacteria have the ability to turn very tiny wheels, when suspended in a special solution. The discovery could enable the creation and development of new classes of bio-inspired, dynamically adaptive materials and structures, for a vast array of applications. Additionally, it has been revealed that even the most common species of bacteria have this ability, so there is no need to grow exotic, potentially dangerous strains for the job.

The discovery has been made by a team of experts from the US Department of Energy's (DOE) Argonne National Laboratory, and the Northwestern University. “The gears are a million times more massive than the bacteria. The ability to harness and control the power of bacterial motions is an important requirement for further development of hybrid biomechanical systems driven by microorganisms,” the physicist and principal investigator of the study, Igor Aronson, explains.

The common aerobic bacterium species Bacillus subtilis was used for the team's experiments. The cellular organisms were placed inside a special solution, together with slanted-spoked microgear. Overall, the bacteria just swam aimlessly around the solution. But, at times, they also touched the wheels and started moving them in a definite direction. This work completed a previous study, published earlier this year, which also showed the potential that the bacteria had in moving mechanical wheels several times their own weight.

“There exists a wide gap between man-made hard materials and living tissues; biological materials, unlike steel or plastics, are 'alive.' Biomaterials, such as live skin or tissue, consume energy of the nutrients to self-repair and adapt to their environment. Our discovery demonstrates how microscopic swimming agents, such as bacteria or man-made nanorobots, in combination with hard materials can constitute a 'smart material' which can dynamically alter its microstructures, repair damage, or power microdevices,” Aronson adds.

The team also managed to devise a way of controlling the speed of the reaction. It says that the aerobic bacteria naturally need oxygen to function, so, by regulating the amount of the chemical in the solution, it can make B. subtilis move faster, or even come to a complete standstill. Adding oxygen into the mix afterwards brings the organisms back to life, and the wheels start moving again. A paper detailing the findings appears in the latest issue of the respected scientific journal Proceedings of the National Academy of Sciences (PNAS).