Alison E. Patteson: 0000-0002-4004-1734

Document Type



Summer 7-17-2019


bacterial swarms, active jamming, light response of bacteria, active matter




NSF Graduate Research Fellowship, UC 2018 Senate CORE Award from the University of California, Merced

Funding ID

NSF-DMR-1104705 and NSFCBET- 1437482


We would like to thank an anonymous reviewer for the suggestion to use the ImageJ plugin Directional J.

Official Citation

Yang J, Arratia PE, Patteson AE, Gopinath A. Quenching active swarms: effects of light exposure on collective motility in swarming Serratia marcescens. J R Soc Interface. 2019 Jul 26;16(156):20180960. doi: 10.1098/rsif.2018.0960. Epub 2019 Jul 17. PMID: 31311436; PMCID: PMC6685032.




Swarming colonies of the light-responsive bacteria Serratia marcescens grown on agar exhibit robust fluctuating large-scale flows that include arrayed vortices, jets and sinuous streamers. We study the immobilization and quenching of these collective flows when the moving swarm is exposed to intense wide-spectrum light with a substantial ultraviolet component. We map the emergent response of the swarm to light in terms of two parameters-light intensity and duration of exposure-and identify the conditions under which collective motility is impacted. For small exposure times and/or low intensities, we find collective motility to be negligibly affected. Increasing exposure times and/or intensity to higher values suppresses collective motility but only temporarily. Terminating exposure allows bacteria to recover and eventually reestablish collective flows similar to that seen in unexposed swarms. For long exposure times or at high intensities, exposed bacteria become paralysed and form aligned, jammed regions where macroscopic speeds reduce to zero. The effective size of the quenched region increases with time and saturates to approximately the extent of the illuminated region. Post-exposure, active bacteria dislodge immotile bacteria; initial dissolution rates are strongly dependent on duration of exposure. Based on our experimental observations, we propose a minimal Brownian dynamics model to examine the escape of exposed bacteria from the region of exposure. Our results complement studies on planktonic bacteria, inform models of patterning in gradated illumination and provide a starting point for the study of specific wavelengths on swarming bacteria.

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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