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SUMMARY:Computing the motor torque of a tethered bacterium using numerical
  simulations - Debasish Das (University of Cambridge)
DTSTART:20171207T130000Z
DTEND:20171207T140000Z
UID:TALK96652@talks.cam.ac.uk
CONTACT:Anne Herrmann
DESCRIPTION:The locomotion of bacteria\, such as Escherichia coli\, is pow
 ered by a rotary motor embedded in the cell wall that rotates rigid helica
 l filaments called flagella\, connected to a short elastic hook via a univ
 ersal joint. There have been a few studies to compute the value of the tor
 que of this rotary motor using resistive force theory (Darnton et al.\, Bi
 ophys. J\, 2007). However\, there is a big discrepancy between the observe
 d experimental value\, 1280 pN.nm and that calculated by resistive force t
 heory\, 370 pN.nm. In this work\, we develop a numerical method based on b
 oundary element method and slender body theory to model a bacterium tether
 ed to a wall. Our model predicts the motor torque to range between 500 to 
 850 pN.nm depending on the configuration of the bacterium placed next to a
  solid wall. This shows that hydrodynamics alone cannot explain the discre
 pancy between the values obtained by more accurate numerical simulations a
 nd those observed in experiments. Possible sources of discrepancies includ
 e inaccurate measurement of viscosity in which the bacterium resides and p
 resence of additional rigid body friction due to contact of the rotating f
 lagellum with the wall.
LOCATION:MR11\, Centre for Mathematical Sciences\, Wilberforce Road\, Camb
 ridge
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