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Published on: November 25, 2020
Fluid dynamics and noise in bacterial cell-cell and cell-surface scattering
Knut Drescher1, Jörn Dunkel, Luis H Cisneros
1Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, United Kingdom.
Summary
Stochastic noise, not long-range fluid dynamics, primarily governs bacterial interactions and surface scattering. Short-range forces dominate cell-cell encounters, influencing collective bacterial behaviors and biofilm formation.
Area of Science:
- Microbiology
- Biophysics
- Fluid Dynamics
Background:
- Bacterial processes are influenced by internal and external noise.
- Stochastic fluctuations are key in chemotaxis, but long-range fluid dynamics were thought to dominate cell-cell and cell-surface interactions.
- Collective behaviors like swarming and biofilm formation depend on these interactions.
Purpose of the Study:
- To investigate the relative importance of fluid dynamics and rotational diffusion in bacterial interactions.
- To measure the flow field generated by individual swimming Escherichia coli near surfaces.
- To clarify the mechanisms governing cell-cell and cell-surface scattering.
Main Methods:
- Direct measurement of the bacterial flow field generated by individual swimming Escherichia coli.
- Experiments conducted both far from and near to a solid surface.
- Analysis of fluid dynamics and rotational diffusion effects.
Main Results:
- For cell-cell interactions, thermal and intrinsic stochasticity override long-range fluid dynamics.
- Bacterial interactions are primarily determined by steric collisions and near-field lubrication forces.
- For cell-surface scattering, long-range fluid dynamics are negligible before collision, but can contribute to long residence times after aligning collisions.
Conclusions:
- Short-range forces dominate bacterial cell-cell interactions, linking bacterial suspensions to other self-organizing systems.
- Hydrodynamic effects play a role in bacterial residence times near surfaces after initial contact.
- These findings, based on mechanical properties, are broadly applicable to various microorganisms.
