Engineered bacteria in which motility is reduced by local cell density
generate periodic stripes of high and low density when spotted on agar plates.
We study theoretically the origin and mechanism of this process in a kinetic
model that includes growth and density-suppressed motility of the cells. The
spreading of a region of immotile cells into an initially cell-free region is
analyzed. From the calculated front profile we provide an analytic ansatz to
determine the phase boundary between the stripe and the no-stripe phases. The
influence of various parameters on the phase boundary is discussed.Comment: 5 pages, 3 figures. Phys. Rev. Lett. in press (2012
