Two French research groups belonging to INSERM and CNRS at Aix-Marseilles University show for the first time that both bacterium adhesion to and bacterium motion on a surface are driven by the same mechanism. The results were published in PNAS.
Up until now, it was believed that the motion of a bacterium on a surface was caused by projection of a polymeric material referred to as slime that would be produced at the bacterium rear. The Marseilles-based scientists' work proves that slime is being generated at spots spread out all along a bacterium's body as opposed to the rear as seemed to be agreed upon in the scientific literature. The role played by this slime appears to be two-fold: it works as a glue so that a bacterium can stick to a surface, and it facilitates bacterium motion by lubricating the surface-to-bacterium contact.
The scientists used SEEC microscopy with substituting Surf slides (Nanolane, France). With Surfs microscope slides it is possible to let a reflected light microscope image samples in an aqueous medium with a sensitivity level of under one nanometre.
A. Ducret, M-P. Valignat, F. Mouhamar, T. Mignot, O. Theodoly: Wet-Surface-Enhanced Ellipsometric Contrast Microscopy identifies slime as a major adhesion factor during bacterial surface motility, PNAS 2012 June 19, 2012, vol. 109, no. 25, 10036-10041
SEEC video-microscopy of slime deposition by bacteria: http://www.nano-lane.com
Imaging & Microscopy Issue 4 , 2012 as free epaper or pdf download