title: 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.
authors.affiliation: Department of Physics, Clark University, Worcester, Massachusetts 01610, USA.
authors.forename: T
authors.initials: T
authors.lastname: Neicu
authors.forename: A
authors.initials: A
authors.lastname: Pradhan
authors.forename: D A
authors.initials: DA
authors.lastname: Larochelle
authors.forename: A
authors.initials: A
authors.lastname: Kudrolli
mesh_terms: D001412:Bacillus subtilis / Q000254:growth & development* / Q000378:metabolism / Q000528:radiation effects*; D002455:Cell Division / Q000528:radiation effects*; D015169:Colony Count, Microbial; D004777:Environment; D013696:Temperature; D013997:Time Factors; D014466:Ultraviolet Rays