Turning Bacteria Suspensions into Superfluids

Héctor Matías López, Jérémie Gachelin, Carine Douarche, Harold Auradou, Eric Clément
2015 Physical Review Letters  
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 evidences for a low shear Newtonian plateau characterized by a shear viscosity decreasing with concentration. In the semi-dilute regime, for particularly active bacteria, the suspension display a
more » ... on display a "super-fluid" like 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.
doi:10.1103/physrevlett.115.028301 pmid:26207507 fatcat:irqgjelm7jf5jowehoopoxofgy