title: Reversal of bacterial locomotion at an obstacle.
abstract: Recent experiments have shown large-scale dynamic coherence in suspensions of the bacterium B. subtilis, characterized by quorum polarity, collective parallel swimming of cells. To probe mechanisms leading to this, we study the response of individual cells to steric stress, and find that they can reverse swimming direction at spatial constrictions without turning the cell body. The consequences of this propensity to flip the flagella are quantified by measurements of the inward and outward swimming velocities, whose asymptotic values far from the constriction show near perfect symmetry, implying that "forwards" and "backwards" are dynamically indistinguishable, as with E. coli.
authors.affiliation: Department of Physics, University of Arizona, Tucson, Arizona 85721, USA.
authors.forename: Luis
authors.initials: L
authors.lastname: Cisneros
authors.forename: Christopher
authors.initials: C
authors.lastname: Dombrowski
authors.forename: Raymond E
authors.initials: RE
authors.lastname: Goldstein
authors.forename: John O
authors.initials: JO
authors.lastname: Kessler
mesh_terms: D001412:Bacillus subtilis / Q000166:cytology / Q000502:physiology*; D003198:Computer Simulation; D005407:Flagella / Q000502:physiology*; D008954:Models, Biological; D020409:Molecular Motor Proteins / Q000502:physiology*; D009038:Motion
chemical_list: D020409:Molecular Motor Proteins