title: Turning Bacteria Suspensions into Superfluids.
abstract: The rheological response under simple shear of an active suspension of Escherichia coli is determined in a large range of shear rates and concentrations. The effective viscosity and the time scales characterizing the bacterial organization under shear are obtained. In the dilute regime, we bring evidence for a low-shear Newtonian plateau characterized by a shear viscosity decreasing with concentration. In the semidilute regime, for particularly active bacteria, the suspension displays a "superfluidlike" transition where the viscous resistance to shear vanishes, thus showing that, macroscopically, the activity of pusher swimmers organized by shear is able to fully overcome the dissipative effects due to viscous loss.
authors.affiliation: Université Paris-Sud, CNRS, F-91405, Lab FAST, Bâtiment 502, Campus Univ, Orsay F-91405, France.
authors.forename: Héctor Matías
authors.initials: HM
authors.lastname: López
authors.affiliation: Physique et Mécanique des Milieux Hétérogenes (UMR 7636 ESPCI/CNRS/Université P.M. Curie/Université Paris-Diderot), 10 rue Vauquelin, 75005 Paris, France.
authors.forename: Jérémie
authors.initials: J
authors.lastname: Gachelin
authors.affiliation: Laboratoire de Physique des Solides, Université Paris-Sud, CNRS UMR 8502, F-91405 Orsay, France.
authors.forename: Carine
authors.initials: C
authors.lastname: Douarche
authors.affiliation: Université Paris-Sud, CNRS, F-91405, Lab FAST, Bâtiment 502, Campus Univ, Orsay F-91405, France.
authors.forename: Harold
authors.initials: H
authors.lastname: Auradou
authors.affiliation: Physique et Mécanique des Milieux Hétérogenes (UMR 7636 ESPCI/CNRS/Université P.M. Curie/Université Paris-Diderot), 10 rue Vauquelin, 75005 Paris, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Clément
mesh_terms: D001431:Bacteriological Techniques / Q000379:methods*; D004926:Escherichia coli / Q000737:chemistry* / Q000166:cytology*; D012212:Rheology; D013535:Suspensions
chemical_list: D013535:Suspensions