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Does water activity rule P. mirabilis periodic swarming? I. Biochemical and functional properties of the

Elodie Lahaye1, Thierry Aubry, Nelly Kervarec

  • 1Laboratoire des Polymères, Propriétés aux Interfaces et Composites, Université de Bretagne-Sud, Campus de Tohannic, BP573 56017 Vannes Cedex, France.

Biomacromolecules
|March 16, 2007
PubMed

Insights

Bacterial colony swarming periodicity may stem from global properties, not just chemical signals. Researchers identified key extracellular matrix components and found their viscoelasticity depends on hydration.

Area of Science:

  • Microbiology
  • Biophysics
  • Biochemistry

Background:

  • Bacterial colony dynamics involve complex cell interactions and emergent properties like antibiotic resistance.
  • The periodic swarming of Proteus mirabilis colonies is not clearly linked to chemical signaling, suggesting alternative regulatory mechanisms.

Purpose of the Study:

  • To investigate the biochemical and functional properties of the extracellular matrix (ECM) in P. mirabilis colonies.
  • To determine if colony-level properties, specifically the ECM, govern the observed swarming periodicity.

Main Methods:

  • Identification of ECM components, including exopolysaccharides, glycinebetaine, and phenoglycolipids.
  • Rheological, calorimetric, and water sorption experiments on purified exopolysaccharides (EPS).

Main Results:

  • A binary exopolysaccharide mixture (1 and 300 kDa), glycinebetaine, and a phenoglycolipid were identified as key ECM components.
  • Purified EPS demonstrated significant viscoelastic properties, attributed to extensive hydrogen bond networks.
  • The mechanical properties of the ECM were found to be hydration-dependent.

Conclusions:

  • The extracellular matrix of P. mirabilis colonies plays a crucial role in colony dynamics.
  • The viscoelasticity and hydration-dependent properties of the ECM suggest it influences colony behavior, potentially explaining swarming periodicity.
  • This research highlights the importance of global colony properties and ECM composition in bacterial behavior.

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