Research > Bacterial Communication

Bacteria are unicellular organisms, which were considered solitary creatures for a long time. Studies over the past two decades have shown that the collective behaviour of these solitary creatures usually results in complexity that is associated with multicellular behaviour, in response to certain cues the bacteria receive from their environment. Multicellularity confers certain advantages to bacteria such as increased access to resources that cannot be reached by individual cells, resistance to bactericidal agents that kill individual cells, and higher chance of survival by differentiation into cells that exhibit various phenotypes.

Intercellular communication is an important feature of multicellularity. In bacteria, intercellular communication takes place through signalling molecules called autoinducers. Autoinducers are mostly acyl-homoserine lactones (AHLs), which diffuse through the bacterial membranes.Their concentration is an indicator of total density of the bacterial population, as most cells in the group secrete these molecules. It is hypothesized that autoinducers give rise to the phenomenon of quorum sensing, which transforms their response from solitary to collective behaviour. For example, the las and rhl systems of Pseudomonas aeruginosa produce N-3-oxododecanoyl-L-homoserine lactone (3OC12-HSL) and N-butyryl-homoserine lactone (C4-HSL) respectively, which trigger virulence, biofilm formation and swarming motility in P. aeruginosa.

We work on the emergence of collective behavior in bacteria, with Vibrio fischeri as the model system. By making quatitative measurements, we try to understand the effect of chemical signalling and physical crowding on the phenotypes such as luminescence, motility, and biofilm formation.