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Bacterial swarming reduces Proteus mirabilis and Vibrio parahaemolyticus cell stiffness and increases β-lactam susceptibility

Auer, George K. and Oliver, Piercen M. and Rajendram, Manohary and Yao, Qing and Jensen, Grant J. and Weibel, Douglas B. (2018) Bacterial swarming reduces Proteus mirabilis and Vibrio parahaemolyticus cell stiffness and increases β-lactam susceptibility. . (Unpublished)

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Swarmer cells of the gram-negative pathogenic bacteria Proteus mirabilis and Vibrio parahaemolyticus become long (>10-100 microns) and multinucleate during their growth and motility on polymer surfaces. We demonstrate increasing cell length is accompanied by a large increase in flexibility. Using a microfluidic assay to measure single-cell mechanics, we identified large differences in swarmer cell stiffness of (bending rigidity of P. mirabilis, 9.6 x 10^(-22) N m^2; V. parahaemolyticus, 9.7 x 10^(-23) N m^2) compared to vegetative cells (1.4 x 10^(-20) N m^2 and 3.2 x 10^(-22) N m^2, respectively). The reduction in bending rigidity (~3-15 fold) was accompanied by a decrease in the average polysaccharide strand length of the peptidoglycan layer of the cell wall from 28-30 to 19-22 disaccharides. Atomic force microscopy revealed a reduction in P. mirabilis peptidoglycan thickness from 1.5 nm (vegetative) to 1.0 nm (swarmer) and electron cryotomography indicated changes in swarmer cell wall morphology. P. mirabilis and V. parahaemolyticus swarmer cells became increasingly sensitive to osmotic pressure and susceptible to cell wall-modifying antibiotics (compared to vegetative cells)--they were ~30% more likely to die after 3 h of treatment with minimum inhibitory concentrations of the beta-lactams cephalexin and penicillin G. Long, flexible swarmer cells enables these pathogenic bacteria to form multicellular structures and promotes community motility. The adaptive cost of swarming is offset by a fitness cost in which cells are more susceptible to physical and chemical changes in their environment, thereby suggesting the development of new chemotherapies for bacteria that leverage swarming for survival.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Jensen, Grant J.0000-0003-1556-4864
Weibel, Douglas B.0000-0002-7113-1409
Additional Information:The copyright holder for this preprint is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. All rights reserved. No reuse allowed without permission. bioRxiv preprint first posted online Mar. 3, 2018. We thank Linda McCarter for V. parahaemolyticus LM5674, Suckjoon Jun for the psulA plasmid, Cameron Scarlett and Molly Pellitteri-­Hahn for mass spectrometry support, and Julie Last for technical assistance with AFM measurements. This research was supported by NIH grant 1DP2OD008735-­01, National Science Foundation grant DMR-­1121288, a Mao Wisconsin Distinguished Graduate Fellowship (to M.R.), and an NSF postdoctoral fellowship (#1202622 to P.M.O), and the Howard Hughes Medical Institute.
Funding AgencyGrant Number
University of Wisconsin-MadisonUNSPECIFIED
NSF Postdoctoral FellowshipDBI-1202622
Howard Hughes Medical Institute (HHMI)UNSPECIFIED
Subject Keywords:bacterial swarming, bacterial cell mechanics; peptidoglycan; osmotic pressure; antibiotics
Record Number:CaltechAUTHORS:20181031-082235074
Persistent URL:
Official Citation:Bacterial swarming reduces Proteus mirabilis and Vibrio parahaemolyticus cell stiffness and increases β-lactam susceptibility. George K. Auer, Piercen M. Oliver, Manohary Rajendram, Qing Yao, Grant J Jensen, Douglas B. Weibel. bioRxiv 275941; doi:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:90533
Deposited By: Tony Diaz
Deposited On:01 Nov 2018 18:27
Last Modified:01 Nov 2018 18:27

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