The colloidal nature of complex fluids enhances bacterial motility

Kamdar, S., Shin, S., Leishangthem, P. et al.
Nature 603, 819–823 (2022).  link

Synopsis

Nearly fifty years ago, Howard Berg discovered that E. coli moves via a run-and-tumble mechanism.  The motion alternates between two states:  run, where flagella power motion that leads to directed velocity perturbed by thermal orientation fluctuations; tumble, where the bacterium reorients to a randomly chosen direction.  Although many biophysical and biochemical aspects of E. coli  motion are now well understood, a long-standing puzzle was that E. coli seem to swim faster in media crowded with obstacles.  In this paper, Kamdar et al. argue that the bacteria are faster because hydrodynamic interactions with the obstacles make them swim straighter.

See also the associated News & Views perspective by R. Jeanneret and M. Polin,
Nature 603, 795–796 (2022). link