hide
Free keywords:
-
Abstract:
We study colonies of nonmotile, rod-shaped bacteria growing on solid substrates. In our model, bacteria
interact purely mechanically, by pushing each other away as they grow, and consume a diffusing nutrient.
We show that mechanical interactions control the velocity and shape of the advancing front, which leads to
features that cannot be captured by established Fisher-Kolmogorov models. In particular, we find that the
velocity depends on the elastic modulus of bacteria or their stickiness to the surface. Interestingly, we
predict that the radius of an incompressible, strictly two-dimensional colony cannot grow linearly in time,
unless it develops branches. Importantly, mechanical interactions can also account for the nonequilibrium
transition between circular and branching colonies, often observed in the lab.
