Fluctuations and rheology in active bacterial suspensions.
We probe nonequilibrium properties of an active bacterial bath through measurements of correlations of passive tracer particles and the response function of a driven, optically trapped tracer. These measurements demonstrate violation of the fluctuation-dissipation theorem and enable us to extract the power spectrum of the active stress fluctuations. In some cases, we observe 1/sqrt[omega] scaling in the noise spectrum which we show can be derived from a theoretical model incorporating coupled stress, orientation, and concentration fluctuations of the bacteria.
Chen
D T N
DT
Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA.
Lau
A W C
AW
Hough
L A
LA
Islam
M F
MF
Goulian
M
M
Lubensky
T C
TC
Yodh
A G
AG
D018929:Cell Culture Techniques; D004926:Escherichia coli / Q000502:physiology*; D012212:Rheology; D013269:Stochastic Processes; D013535:Suspensions; D014783:Viscosity
D013535:Suspensions