Viscosity suppresses tumbling.
(A) The mean run time increases from 0.95 to 3.51 s as the CMC polymer concentration c increases (MW = 7 × 105). (B) The mean tumble time also increases with c from 0.16 to 0.37 s. (C) The rotational diffusion coefficient decreases with viscosity for the CMC and XG solutions, indicating that suppressed tumbling is nearly independent of MW or molecule and is captured by proposed model. (D) The mean run and (E) mean tumble times for individual tethered cells in Newtonian (PEG, blue squares) and viscoelastic (CMC, orange squares) fluids as a function of (Movie 2). Lines correspond to regression analysis (Methods).