Extinction transition in bacterial colonies under forced convection

Abstract

We report the spatiotemporal response of Bacillus subtilis growing on a nutrient-rich layer of agar to ultraviolet (UV) radiation. Below a crossover temperature, the bacteria are confined to regions that are shielded from UV radiation. A forced convection of the population is effected by rotating a UV radiation shield relative to the Petri dish. The extinction speed at which the bacterial colony lags behind the shield is found to be qualitatively similar to the front velocity of the colony growing in the absence of a hostile environment as predicted by the model of Dahmen, Nelson, and Shnerb. A quantitative comparison is not possible without considering the slow dynamics and time-dependent interaction of the population with the hostile environment.

A quasispecies on a moving oasis

“…They analyzed the dynamics near the extinction and delocalization velocities, where the population is blown off of the oasis. Their predictions have been qualitatively confirmed by recent experiments on Bacillus subtilis growth [5].…”

Self-organization analysis for a nonlocal convective Fisher equation

“…As we have discussed, the NLCFE presents patterns only in the presence of a nonlocal interaction term. Then rescaling the Gaussian distribution (17) for z = Lx, we get…”

“…Many studies on pattern formation have been carried out experimentally on systems in which convection plays an important role. The convective cells of Rayleigh-Bernard instabilities [15], moving Wigner glasses [16], and pattern formation in bacterial colonies under forced convection [17] illustrate the phenomenon of self-organization in convective motion. In these cases, a flux of particles is expected to undergo a new regime of organization at the threshold of external parameters.…”

Hierarchical population model with a carrying capacity distribution for bacterial biofilms

“…These patches are assumed to be of characteristic size 1/λ, where λ is a scale factor central to the model. Alternative ways of inducing spatially non-uniform growth or depletion are to apply, for photosynthetic bacteria, favourable or unfavourable (UV) illumination according to a structured or random spatial pattern [1,2].…”