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SUMMARY:Transition to bound states for bacteria swimming near surfaces - D
 ebasish Das (University of Cambridge)
DTSTART:20191017T120000Z
DTEND:20191017T130000Z
UID:TALK131656@talks.cam.ac.uk
CONTACT:Anne Herrmann
DESCRIPTION:It is well known that flagellated bacteria swim in circles nea
 r surfaces. However\, recent experiments have shown that a sulfide-oxidizi
 ng bacterium named Thiovulum majus\, whose typical size ranges from 5μm t
 o 25 μm\, can transition from swimming in circles to a surface bound stat
 e where it stops swimming while remaining free to move laterally along the
  surface. In this bound state\, the cell rotates perpendicular to the surf
 ace with its flagella pointing away from it. Using numerical simulations a
 nd theoretical analysis\, we demonstrate the existence of a fluid-structur
 e interaction instability that causes cells with relatively short flagella
  to become surface bound. These results have significant implications on t
 he initial stages of formation of the white veil\, an approximately 0.5-mm
 -thick elastic porous medium that is the natural habitat of T. majus cells
 . While in this work\, we have focused only on the surface binding phenome
 na\, there are other questions related to T. majus locomotion dynamics rem
 ain unanswered. T. Majus is the second fastest swimming bacterium in natur
 e reaching speeds up to 615 μm/s. How are these cells able to swim so fas
 t? Do they possess an elastic hook like the well-studied E. coli and if ye
 s\, how do hooks affect the propulsion of these microorganisms. (Note: I w
 ill comment on the suitability of boundary element method at resolving ver
 y small gaps between surfaces.)\n
LOCATION:MR11\, Centre for Mathematical Sciences\, Wilberforce Road\, Camb
 ridge
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