Quorum sensing and its role in colony dynamics of Pseudomonas aeruginosa

Quorum sensing (QS) describes a communication mechanism via signal molecules that allows colonies of bacteria to coordinate gene expression, including for virulence factors, swarming motility and complex social traits. The nature of the QS system depends very much on the species.

Pseudomonas aeruginosa was chosen as a model species for this research. P. aeruginosa is a Gram-negative bacterium that is responsible for a wide range of infections in humans. The QS signalling system of P. aeruginosa is known to involve multiple control components, notably the las, rhl, and pqs systems; this talk focuses on the first two. Dr Alfiniyah will examine the las system and, in particular, the repressive interaction of rsaL, an embedded small regulative protein, employing recent biochemical information to aid model construction.

Using analytical and numerical methods, Dr Alfiniyah will show how this feature of the las system can give rise to excitable pulse generation with important downstream impact on the rhl system. The las-rhl interaction provides a ‘quorum memory’ that allows cells to trigger rhamnolipid production when they are at the edge of the colony. Dr Alfiniyah will demonstrate how the dynamical QS system in individual cells and with coupling between cells can affect the dynamics of the bacterial colony.

Tea, coffee and discussion in room 6.314 afterwards. All welcome!