Bacteria Take On Completely New Flat Shape To Fit Through Nanoslits
ScienceDaily (Sep. 9, 2009) — It appears that bacteria can squeeze through practically anything. In extremely small nanoslits they take on a completely new flat shape. Even in this squashed form they continue to grow and divide at normal speeds. This has been demonstrated by research carried out at TU Delft's Kavli Institute of Nanoscience. The results will be appearing this week in the online edition of the scientific journal Proceedings of the National Academy of Sciences (PNAS) and as the cover article in the September 1 print issue of PNAS.


Using nanofabrication, Delft scientists made minuscule channels, measuring a micrometer or less in width and 50 micrometer in length, on a silicon chip between tiny chambers containing bacteria. Subsequently they studied the behaviour of Escherichia. coli and Bacillus. subtilis bacteria in this artificial environment. The bacteria were genetically modified so that they were fluorescent and could easily be followed using a special microscope.

Squashed flat

Under normal circumstances these bacteria swim and this research showed that they retain this motility in surprisingly narrow channels. They swam just as actively as usual even in channels that were only 30 percent wider than their own diameter (of about 1 micrometer). In even narrower submicron channels the bacteria stopped swimming, and an unexpected effect took place: The bacteria were able to make their way through ultra-narrow passageways in another manner, that is by growing and dividing. The researchers found that this way, E. coli bacteria could squeeze through narrow slits that were only half their own diameter in width.

Post-doctoral researcher, Jaan Männik said, "This took us totally by surprise. The bacteria become completely flattened. They have all sorts of peculiar shapes both in the channels and when they finally come out at the other side. What is really remarkable, however, is that in the channels, and therefore under extreme confinement, they continue to grow and divide at normal speeds. Apparently their shape is not a determining factor for these activities."