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Reduction of viscosity in suspension of swimming bacteria
Andrey Sokolov1, Igor S Aranson
1Illinois Institute of Technology, 3101 South Dearborn Street, Chicago, Illinois 60616, USA.
Abstract:
Measurements of the shear viscosity in suspensions of swimming Bacillus subtilis in free-standing liquid films have revealed that the viscosity can decrease by up to a factor of 7 compared to the viscosity of the same liquid without bacteria or with nonmotile bacteria. The reduction in viscosity is observed in two complementary experiments: one studying the decay of a large vortex induced by a moving probe and another measuring the viscous torque on a rotating magnetic particle immersed in the film. The viscosity depends on the concentration and swimming speed of the bacteria.
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