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TZID:Europe/Paris
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BEGIN:VEVENT
UID:1-369@lptms.universite-paris-saclay.fr
DTSTART:20150921T110000Z
DTEND:20150921T120000Z
DTSTAMP:20150907T062807Z
URL:http://www.lptms.universite-paris-saclay.fr/seminars/physics-biology-i
 nterface-seminar-agnese-seminara/
SUMMARY:Physics-Biology interface seminar: Agnese Seminara - Moyen Amphi\, 
 Building 510\, Université Paris-Saclay Orsay - 21 Sep 15 11:00
DESCRIPTION:Osmotic spreading of Bacillus subtilis biofilms\nAgnese Seminar
 a (LPMC\, Université de Nice)\n\nBacterial biofilms are organized communi
 ties of cells living in association with surfaces. The hallmark of biofilm
  formation is a well defined spatio-temporal pattern of gene expression\, 
 leading to differentiation and a complex morphology. While this process re
 sembles the development of a multicellular organism\, biofilms are only tr
 ansiently multicellular. More importantly the functions associated to the 
 biofilm phenotype are largely unknown. \n\n\nA common feature of biofilm f
 ormation is the secretion of a polymeric matrix rich in sugars and protein
 s in the extracellular space. In Bacillus subtilis\, secretion of the exop
 olysaccharide (EPS) component of the extracellular matrix is genetically c
 oupled to the inhibition of flagella-mediated motility. The onset of this 
 switch results in slow expansion of the biofilm on a substrate. Different 
 strains have radically different capabilities in surface colonization: Fla
 gella-null strains spread at the same rate as wild type\, while both are d
 ramatically faster than EPS mutants. Multiple functions have been attribut
 ed to the EPS\, but none of these provides a physical mechanism for genera
 ting spreading. We propose that the secretion of EPS drives surface motili
 ty by generating osmotic pressure gradients in the extracellular space. A 
 simple mathematical model based on the physics of polymer solutions shows 
 quantitative agreement with experimental measurements of biofilm growth\, 
 thickening\, and spreading. We discuss the implications of this osmoticall
 y driven type of surface motility for nutrient uptake that may elucidate t
 he reduced fitness of the matrix-deficient mutant strains. \n
CATEGORIES:physbio,seminars
LOCATION:Moyen Amphi\, Building 510\, Université Paris-Saclay Orsay\, 15 R
 ue Georges Clemenceau\, orsay\, France
GEO:48.698187;2.181768
X-APPLE-STRUCTURED-LOCATION;VALUE=URI;X-ADDRESS=15 Rue Georges Clemenceau\,
  orsay\, France;X-APPLE-RADIUS=100;X-TITLE=Moyen Amphi\, Building 510\, Un
 iversité Paris-Saclay Orsay:geo:48.698187,2.181768
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