title: Bacterial growth and form under mechanical compression.
abstract: A combination of physical and chemical processes is involved in determining the bacterial cell shape. In standard medium, Escherichia coli cells are rod-shaped, and maintain a constant diameter during exponential growth. Here, we demonstrate that by applying compressive forces to growing E. coli, cells no longer retain their rod-like shapes but grow and divide with a flat pancake-like geometry. The deformation is reversible: deformed cells can recover back to rod-like shapes in several generations after compressive forces are removed. During compression, the cell elongation rate, proliferation rate, DNA replication rate, and protein synthesis are not significantly altered from those of the normal rod-shaped cells. Quantifying the rate of cell wall growth under compression reveals that the cell wall growth rate depends on the local cell curvature. MreB not only influences the rate of cell wall growth, but also influences how the growth rate scales with cell geometry. The result is consistent with predictions of a mechanochemical model, and suggests an active mechanical role for MreB during cell wall growth. The developed compressive device is also useful for studying a variety of cells in unique geometries.
authors.affiliation: Department of Mechanical Engineering and Johns Hopkins Physical Sciences-Oncology Center, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: Fangwei
authors.initials: F
authors.lastname: Si
authors.affiliation: Department of Mechanical Engineering and Johns Hopkins Physical Sciences-Oncology Center, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: Bo
authors.initials: B
authors.lastname: Li
authors.affiliation: Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, Houston, TX 77030, USA.
authors.forename: William
authors.initials: W
authors.lastname: Margolin
authors.affiliation: Department of Mechanical Engineering and Johns Hopkins Physical Sciences-Oncology Center, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: Sean X
authors.initials: SX
authors.lastname: Sun
mesh_terms: D001419:Bacteria / Q000166:cytology*; D018407:Bacterial Physiological Phenomena; D002455:Cell Division; D002473:Cell Wall / Q000378:metabolism; D004261:DNA Replication; D004926:Escherichia coli / Q000166:cytology / Q000502:physiology; D044085:Microfluidics / Q000295:instrumentation / Q000379:methods; D014176:Protein Biosynthesis; D013314:Stress, Mechanical