Sept 16 : The kinky motion of a primitive spiral-shaped bacterium in fluid, could help design efficient micromachines of the future, a new study by German physicists from the Technical University Munich, has revealed.

Roland Netz and his team have developed a computer model of the motion of Spiroplasma, which swims through fluid by sending kinks down its body.

The scientists believe their results could be important for one day designing micromachines that might be used for microscale manufacturing or for medical procedures.

“Our results could provide fresh ideas for developing artificial micromachines that work efficiently on the nano- and micro-scales. This is currently a hot topic in nanotechnology,” said Netz.

Many bacteria, such as E. coli, have flagella or other propeller-like appendages, which they use to swim. The flagella are essentially powered by “motors” embedded in the bacterium’s cell wall. If the motors all rotate counter-clockwise in a viscous liquid like water, the flagella bundle together and push the organism forward in an approximately straight line.

Now, new calculations by Netz and Hirofumi Wada, also of the Technical University Munich, has revealed that the 200 nanometres wide and a few microns long Spiroplasma moves through water rather like a corkscrew in cork of a wine bottle.

Spiroplasma is very different from other bacteria in the sense that it does not have a rigid cell wall, or flagella, but moves using body as one giant flagellum – continually changing its body shape to push itself forward.

The Spiroplasma sends a pair of kinks down its body as it switches its body from a right-handed spiral to a left-handed one, and vice versa. The net effect is a zig-zagging forward motion.

Further studies revealed that such a style is optimised for fast swimming on the micro scale, and for efficiently converting energy into motion.

Now, the team has modelled this motion, using the properties of an elastic rod, to mimic the Spiroplasma.

Studying the dynamic interplay between the deforming rod and the surrounding fluid’s “flow field” allowed the researchers to explain the helical movement of Spiroplasma swimming.

“It’s a very entertaining result and [the movement] seems plausible. I do not understand exactly how the exterior membrane of this organism tolerates the strain it must experience, but it clearly does,” New Scientist quoted George Whitesides of Harvard University, who also studies bacterial motion, as saying. (ANI)