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Coiled to Diffuse: BrownianMotion of a Helical Bacterium.

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Bibliographic Details
Title:	Coiled to Diffuse: BrownianMotion of a Helical Bacterium.
Authors:	Butenko, Alexander V.¹, Mogilko, Emma¹, Amitai, Lee¹, Pokroy, Boaz¹, Sloutskin, Eli¹
Source:	Langmuir. Sep2012, Vol. 28 Issue 36, p12941-12947. 7p.
Subjects:	Spirochetes, Wiener processes, Helical structure, Diffusion, Comparative studies, Physics experiments
Abstract:	We employ real-time three-dimensional confocal microscopyto followthe Brownian motion of a fixed helically shaped Leptospirainterrogans(LI) bacterium. We extract from our measurementsthe translational and the rotational diffusion coefficients of thisbacterium. A simple theoretical model is suggested, perfectly reproducingthe experimental diffusion coefficients, with no tunable parameters.An older theoretical model, where edge effects are neglected, dramaticallyunderestimates the observed rates of translation. Interestingly, thecoiling of LI increases its rotational diffusion coefficient by afactor of 5, compared to a (hypothetical) rectified bacterium of thesame contour length. Moreover, the translational diffusion coefficientswould have decreased by a factor of â¼1.5, if LI were rectified.This suggests that the spiral shape of the spirochaete bacteria, inaddition to being employed for their active twisting motion, may alsoincrease the ability of these bacteria to explore the surroundingfluid by passive Brownian diffusion. [ABSTRACT FROM AUTHOR]
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Database:	Engineering Source

Description
Abstract:	We employ real-time three-dimensional confocal microscopyto followthe Brownian motion of a fixed helically shaped Leptospirainterrogans(LI) bacterium. We extract from our measurementsthe translational and the rotational diffusion coefficients of thisbacterium. A simple theoretical model is suggested, perfectly reproducingthe experimental diffusion coefficients, with no tunable parameters.An older theoretical model, where edge effects are neglected, dramaticallyunderestimates the observed rates of translation. Interestingly, thecoiling of LI increases its rotational diffusion coefficient by afactor of 5, compared to a (hypothetical) rectified bacterium of thesame contour length. Moreover, the translational diffusion coefficientswould have decreased by a factor of â¼1.5, if LI were rectified.This suggests that the spiral shape of the spirochaete bacteria, inaddition to being employed for their active twisting motion, may alsoincrease the ability of these bacteria to explore the surroundingfluid by passive Brownian diffusion. [ABSTRACT FROM AUTHOR]
ISSN:	07437463
DOI:	10.1021/la302056j