Berlin 2015 – scientific programme

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BP: Fachverband Biologische Physik

BP 45: Systems biology

BP 45.3: Talk

Thursday, March 19, 2015, 15:30–15:45, H 1028

Spatio-temporal dynamics of segregation in gonococcal populations — •Enno R. Oldewurtel, Nadzeya Kouzel, and Berenike Maier — Department of Physics, University of Cologne

Various bacterial pathogens evolved to escape the host immune system by reversibly switching off the generation of surface molecules via mutations. This can generate heterogeneity within a population. However, new mutant cells are likely to get lost again due to stochastic fluctuations before increasing in number. Hence, it is unclear how heterogeneity can evolve and be maintained.

The human pathogen Neisseria gonorrhoeae can undergo frequent changes in its major virulence factor, a long polymeric cell appendage, called type IV pilus. It can switch on and off modifications or production of this structure. Type IV pili mediate aggregation among bacteria. Thus changes in the pilus, can lead to changes in the physico-chemical interaction between cells. Here, we address the spatio-temporal dynamics of emergence and spreading of bacteria with modified or lacking type IV pili, within a growing colony of N. gonorrhoeae.

We are able to directly visualise mutants via fluorescent proteins. Mutants gaining the ability to modify their pili by glycosylation and mutants no longer producing pili, were seen to spread more easily within the population. We attribute this effect to decreased cell-to-cell interaction by either changing the pilus or lacking it.

We conclude that fine-tuning of physical interactions can lead to segregation into sub-populations, thus maintaining the heterogeneity and co-existence of multiple phenotypes.