title: Does water activity rule P. mirabilis periodic swarming? II. Viscoelasticity and water balance during swarming.
abstract: Following the analysis of the biochemical and functional properties of the P. mirabilis extra cellular matrix performed in the first part of this study, the viscoelasticity of an actively growing colony was investigated in relation to water activity. The results demonstrate that the P. mirabilis colony exhibits a marked viscoelastic character likely due to both cell rafts and exoproduct H-bond networks. Besides, the water loss by evaporation during migration has been measured, whereas the experimental determination of the water diffusion coefficient in agar has allowed us to estimate the net water influx at the agar/colony interface. These data drive us to propose that a periodic increase of the water activity at the colony's periphery, mainly due to the drastic surface to volume ratio increase associated with swarming, causes the periodic and synchronous cessation of migration through the dissociation of exoproduct networks, which in turn strongly alters the matrix viscoelasticity.
authors.affiliation: Laboratoire des Polymères, Propriétés aux Interfaces et Composites, Université de Bretagne-Sud, Campus de Tohannic, BP573 56017 Vannes Cedex, France.
authors.forename: Elodie
authors.initials: E
authors.lastname: Lahaye
authors.forename: Thierry
authors.initials: T
authors.lastname: Aubry
authors.forename: Vincent
authors.initials: V
authors.lastname: Fleury
authors.forename: Olivier
authors.initials: O
authors.lastname: Sire
mesh_terms: D005109:Extracellular Matrix / Q000737:chemistry*; D008055:Lipids / Q000032:analysis; D009682:Magnetic Resonance Spectroscopy / Q000379:methods / Q000592:standards; D010316:Particle Size; D011513:Proteus mirabilis / Q000737:chemistry* / Q000502:physiology; D012015:Reference Standards; D012680:Sensitivity and Specificity; D013997:Time Factors; D014783:Viscosity; D014867:Water / Q000737:chemistry
chemical_list: D008055:Lipids; D014867:Water