Quantitative snapshots of bacterial motility

Condensed Matter lunchtime seminar

Quantitative snapshots of bacterial motility

  • Event time: 1:00pm
  • Event date: 19th October 2009
  • Speaker: Laurence Wilson (Formerly School of Physics & Astronomy, University of Edinburgh)
  • Location: Room 2511,

Event details

I will present two new techniques for quantifying bacterial motility; DDM and DFM. Both techniques utilise movies acquired at a very high speed, up to 800 frames (~1GB) per second per second. E. coli strains AB1157, HCB437 and HCB1 have so far been studied, and I will present data from these three strains. DDM was originally applied to colloids by Cerbino and Trappe, but modified and adapted at Edinburgh for use with bacterial samples. A microscope is used to produce light scattering-like data at 'angles' well below those easily achievable by DLS. This allows us to take a snapshot of the average swimming speed of around 4000 bacteria, and unlike other current methods, doesn't rely on particle tracking. The second technique uses an obliquely illuminated sample (i.e. darkfield microscopy); bacteria in the sample scatter different amounts of light depending upon their orientation with respect to the illumination direction. By examining intensity fluctuations within small regions of the sample, we can identify characteristic frequencies both of bacterial body rotation and (more indirectly) flagellar rotation. If time permits, I will go on to present results of these methods being applied to bacteria swimming (or not) in a polymer solution.

This is a weekly series of informal talks given primarily by members of the soft condensed matter and statistical mechanics groups, but is also open to members of other groups and external visitors. The aim of the series is to promote discussion and learning of various topics at a level suitable to the broad background of the group. Everyone is welcome to attend..

Find out more about Condensed Matter lunchtime seminars.