Swarming dynamics in bacterial colonies

H. P. Zhang, Avraham Be'Er, Rachel S. Smith, E. L. Florin, Harry L. Swinney

Research output: Contribution to journalArticlepeer-review

94 Scopus citations

Abstract

We determine and relate the characteristic velocity, length, and time scales for bacterial motion in swarming colonies of Paenibacillus dendritiformis growing on semi-solid agar substrates. The bacteria swim within a thin fluid layer, and they form long-lived jets and vortices. These coherent structures lead to anisotropy in velocity spatial correlations and to a two-step relaxation in velocity temporal correlations. The mean squared displacement of passive tracers exhibits a short-time regime with nearly ballistic transport and a diffusive long-time regime. We find that various definitions of the correlation length all lead to length scales that are, surprisingly, essentially independent of the mean bacterial speed, while the correlation time is linearly proportional to the ratio of the correlation length to the mean speed.

Original languageEnglish
Article number48011
JournalEPL
Volume87
Issue number4
DOIs
StatePublished - 1 Aug 2009
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy (all)

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