  Guided movement in response to slowly diffusing polymeric trails provides a
unique mechanism for self-organization of some microorganisms. To elucidate how
this signaling route leads to microcolony formation, we experimentally probe
the trajectory and orientation of Pseudomonas aeruginosa that propel themselves
on a surface using type IV pili motility appendages, which preferentially
attach to deposited exopolysaccharides. We construct a stochastic model by
analyzing single-bacterium trajectories, and show that the resulting
theoretical prediction for the many-body behavior of the bacteria is in
quantitative agreement with our experimental characterization of how cells
explore the surface via a power law strategy.
