title: Filling an emulsion drop with motile bacteria.
abstract: We have measured the spatial distribution of motile Escherichia coli inside spherical water droplets emulsified in oil. At low cell concentrations, the cell density peaks at the water-oil interface; at increasing concentration, the bulk of each droplet fills up uniformly while the surface peak remains. Simulations and theory show that the bulk density results from a "traffic" of cells leaving the surface layer, increasingly due to cell-cell scattering as the surface coverage rises above ∼10%. Our findings show similarities with the physics of a rarefied gas in a spherical cavity with attractive walls.
authors.affiliation: SUPA and The School of Physics & Astronomy, The University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh EH9 3JZ, United Kingdom.
authors.forename: I D
authors.initials: ID
authors.lastname: Vladescu
authors.affiliation: SUPA and The School of Physics & Astronomy, The University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh EH9 3JZ, United Kingdom.
authors.forename: E J
authors.initials: EJ
authors.lastname: Marsden
authors.affiliation: SUPA and The School of Physics & Astronomy, The University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh EH9 3JZ, United Kingdom.
authors.forename: J
authors.initials: J
authors.lastname: Schwarz-Linek
authors.affiliation: SUPA and The School of Physics & Astronomy, The University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh EH9 3JZ, United Kingdom.
authors.forename: V A
authors.initials: VA
authors.lastname: Martinez
authors.affiliation: SUPA and The School of Physics & Astronomy, The University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh EH9 3JZ, United Kingdom.
authors.forename: J
authors.initials: J
authors.lastname: Arlt
authors.affiliation: SUPA and The School of Physics & Astronomy, The University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh EH9 3JZ, United Kingdom.
authors.forename: A N
authors.initials: AN
authors.lastname: Morozov
authors.affiliation: SUPA and The School of Physics & Astronomy, The University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh EH9 3JZ, United Kingdom.
authors.forename: D
authors.initials: D
authors.lastname: Marenduzzo
authors.affiliation: SUPA and The School of Physics & Astronomy, The University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh EH9 3JZ, United Kingdom.
authors.forename: M E
authors.initials: ME
authors.lastname: Cates
authors.affiliation: SUPA and The School of Physics & Astronomy, The University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh EH9 3JZ, United Kingdom.
authors.forename: W C K
authors.initials: WC
authors.lastname: Poon
mesh_terms: D004655:Emulsions; D004926:Escherichia coli / Q000502:physiology*; D008954:Models, Biological; D009821:Oils / Q000737:chemistry; D013499:Surface Properties; D013550:Swimming; D014867:Water / Q000737:chemistry
chemical_list: D004655:Emulsions; D009821:Oils; D014867:Water