Philippe Remigi: The evolution of phenotypic heterogeneity in Pseudomonas fluorescens

  • Date: Apr 24, 2018
  • Time: 11:00 AM - 12:00 PM (Local Time Germany)
  • Speaker: Philippe Remigi from Massey University, New Zealand
  • Please find more information on Philippe Remigi here:
  • Location: MPI Plön
  • Room: Lecture hall
  • Host: Paul Rainey


Observations of bacteria at the single-cell level have revealed many instances of phenotypic heterogeneity within otherwise clonal populations, but the selective causes, molecular bases and broader ecological relevance of these phenomena remain poorly understood. In an earlier experiment in which the bacterium Pseudomonas fluorescens SBW25 was propagated under a selective regime that mimicked the host immune response, a genotype evolved that stochastically switched between capsulation states. The genetic cause was a mutation that decreased the pool of intracellular pyrimidine metabolites (and growth rate), lowering the activation threshold of a pre-existing but hitherto unrecognised phenotypic switch. Here I will describe our recent efforts to understand the molecular mechanisms responsible for the bistable expression of extracellular capsules. This work led us to realise that, in the ancestral bacterium, the switch is part of a programme that determines stochastic entry into the semi-quiescent capsulated state, but also enables these cells to exit rapidly from stationary phase under permissive conditions.

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