Joge, S. | Search bioRxiv

bioRxiv2018

Two-component systems regulate swarming in Pseudomonas aeruginosa PA14

Swarming in Pseudomonas aeruginosa is a quorum-dependant motility over semi-solid surfaces. On soft agar, P. aeruginosa exhibits a dendritic swarm pattern, with multiple levels of branching. Swarm patterns vary considerably depending upon the experimental design. In the present study, we show that the swarm pattern is plastic and media dependent. We define several quantifiable, macroscale features of the swarm to study the plasticity observed across media. Further, through a targeted screen of 113 genes encoding two-component system (TCS) components, we show that 44 TCS genes regulate PA14 swarming in a contextual fashion. However, only four TCS genes are essential for swarming. Many swarming-defective TCS mutants are highly efficient in biofilm formation indicating an antagonistic relationship between swarming and biofilm states in P. aeruginosa.

microbiology↗

bioRxiv2018

Spatial Awareness of a Bacterial Swarm

Bacteria are perhaps the simplest living systems capable of complex behaviour involving sensing and coherent, collective behaviour an example of which is the phenomena of swarming on agar surfaces. Two fundamental questions in bacterial swarming is how the information gathered by individual members of the swarm is shared across the swarm leading to coordinated swarm behaviour and what specific advantages does membership of the swarm provide its members in learning about their environment. In this article, we show a remarkable example of the collective advantage of a bacterial swarm which enables it to sense inert obstacles along its path. Agent based computational model of swarming revealed that independent individual behaviour in response to a two-component signalling mechanism could produce such behaviour. This is striking because independent individual behaviour without any explicit communication between agents was found to be sufficient for the swarm to effectively compute the gradient of signalling molecule concentration across the swarm and respond to it.

biophysics↗