Format

Send to

Choose Destination
Biophys J. 2013 Oct 15;105(8):1915-24. doi: 10.1016/j.bpj.2013.08.047.

A bacterial swimmer with two alternating speeds of propagation.

Author information

1
Institut für Physik und Astronomie, Universität Potsdam, Potsdam, Germany.

Abstract

We recorded large data sets of swimming trajectories of the soil bacterium Pseudomonas putida. Like other prokaryotic swimmers, P. putida exhibits a motion pattern dominated by persistent runs that are interrupted by turning events. An in-depth analysis of their swimming trajectories revealed that the majority of the turning events is characterized by an angle of ϕ1 = 180° (reversals). To a lesser extent, turning angles of ϕ2 = 0° are also found. Remarkably, we observed that, upon a reversal, the swimming speed changes by a factor of two on average-a prominent feature of the motion pattern that, to our knowledge, has not been reported before. A theoretical model, based on the experimental values for the average run time and the rotational diffusion, recovers the mean-square displacement of P. putida if the two distinct swimming speeds are taken into account. Compared to a swimmer that moves with a constant intermediate speed, the mean-square displacement is strongly enhanced. We furthermore observed a negative dip in the directional autocorrelation at intermediate times, a feature that is only recovered in an extended model, where the nonexponential shape of the run-time distribution is taken into account.

PMID:
24138867
PMCID:
PMC3797586
DOI:
10.1016/j.bpj.2013.08.047
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Elsevier Science Icon for PubMed Central
Loading ...
Support Center