2011/06/20 by Knut Drescher, Jörn Dunkel, Luis Cisneros +4 · 18 citations
Chemistry · Engineering · Physics and Astronomy · #Bacteria #Bacterial cell structure #Biofilm #Biology #Biophysics #Cell biology #Chemical physics #Chemistry #Chemotaxis #Mechanics #Micro and Nano Robotics #Microfluidic and Bio-sensing Technologies #Molecular Communication and Nanonetworks #Motility #Optics #Physics #Scattering #cond-mat.soft #cond-mat.stat-mech #physics.bio-ph #physics.flu-dyn
paper · pdf · doi:10.1073/pnas.1019079108
published as PNAS, vol. 108, pages 10940-10945, 2011 · 9 pages, 2 figures, http://www.pnas.org/content/108/27/10940
openalex publication_date 2011/06/20 · arxiv created 2011/07/12 · arxiv updated 2011/07/13 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Bacterial processes ranging from gene expression to motility and biofilm formation are constantly challenged by internal and external noise. While the importance of stochastic fluctuations has been appreciated for chemotaxis, it is currently believed that deterministic long-range fluid dynamical effects govern cell-cell and cell-surface scattering-the elementary events that lead to swarming and collective swimming in active suspensions and to the formation of biofilms. Here, we report direct measurements of the bacterial flow field generated by individual swimming Escherichia coli both far from and near to a solid surface. These experiments allowed us to examine the relative importance of fluid dynamics and rotational diffusion for bacteria. For cell-cell interactions it is shown that thermal and intrinsic stochasticity drown the effects of long-range fluid dynamics, implying that physical interactions between bacteria are determined by steric collisions and near-field lubrication forces. This dominance of short-range forces closely links collective motion in bacterial suspensions to self-organization in driven granular systems, assemblages of biofilaments, and animal flocks. For the scattering of bacteria with surfaces, long-range fluid dynamical interactions are also shown to be negligible before collisions; however, once the bacterium swims along the surface within a few microns after an aligning collision, hydrodynamic effects can contribute to the experimentally observed, long residence times. Because these results are based on purely mechanical properties, they apply to a wide range of microorganisms.