Lost in the thicket: how agar can suppress bacterial chemotaxis

Condensed Matter lunchtime seminar

Lost in the thicket: how agar can suppress bacterial chemotaxis

  • Event time: 1:00pm
  • Event date: 7th April 2008
  • Speaker: Ottavio Croze (University of Edinburgh)
  • Location: Room 2511,

Event details

Bacteria often dwell in porous habitats (e.g. soil, food, ...) where successful colonisation and survival often depend crucially on chemotactic** motility. Agar, a polysaccharide gel, is seldom thought of as porous when studying bacteria. High agar concentrations (10-20 g/litre) are mixed with nutrients to make ''hard'' gels on which cells are cultured. When studying bacterial chemotactic motility, however, lower (''soft'') concentrations (1-4 g/litre) are employed to make gels which are penetrable by bacteria. The chemotactic motion of bacteria in liquid environments has been extensively studied, and is well understood. The study of bacteria in gels, however, is found wanting. The understanding of bacteria in similarly porous media is more advanced, but also incomplete. One would expect bacterial chemotactic motion in a gel (porous medium) to be perturbed by the latter's microstructure. Indeed, amongst other results, in this seminar I will present evidence of the drastic changes a gelatinous environment can affect on bacterial motion: increasing agar concentration (within the ''soft'' range) can ''switch off'' chemotaxis in a population of Escherichia coli cells genetically capable of chemotactic response.

** The ability of organisms to direct their motion towards chemically favourable environments and away from toxic ones is known as chemotaxis.

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..

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