8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

P10.22Tue 611:23-14:00Dynamics and motility of swimming E. coli bacteria inpolymer solutionVincent Martinez, 1 Jana Schwarz-Linek, 1 Mathias Reufer, 1 Laurence Wilson, 2Alexander Morozov, 1 and Wilson Poon 11 University of Edinburgh, Room 2609, JCMB, The King’s Buildings, EH9 3JZ, Edinburgh,United Kingdom2 The Rowland Institute at Harvard, Cambridge, Massachusetts, USAWhile E. coli motility is reasonably well understood in aqueous media, there are only few experimentalstudies in polymer solution. Here, we present a new experimental study of swimmingE. coli bacteria in a polymer solution using two recently developed microscope-based methods[1, 2]. Specifically, we measured the swimming speed (v), body (W) and flagellar (w) rotationalfrequencies, averaged over ∼ 10 4 cells, as function of polymer concentration and molecularweight. In addition, our polymer solutions were carefully characterized using rheometry anddynamic light scattering. Using the commercial polymer as received, we substantially reproducedthe peak in the swimming speed versus polymer concentration found in the most extensive workto date [3]. However, both body and flagella rotational frequencies also show a peak, suggestingan extra source of proton motive force in the polymer solution. In contrast, using clean polymer(obtained from dialysis), there is no peak in any of the three quantities (v, W, w) but rather aplateau at low concentration. At higher polymer concentration, a significant decrease is observed,which seems to show interesting scaling with viscosity. Our measurements give, for the firsttime, a comprehensive picture of the motility of E. coli in a polymer solution with polymerconcentration varying from 0 to well beyond the overlap concentration (c ⋆ ). Such knowledgeforms a basis for tackling pathogens that infect mucus-lined epithelial surfaces in humans andother higher animals.[1] Wilson LG, Martinez VA, Schwarz-Linek J, Tailleur J, Bryant G, Pusey PN and PoonWCK, Differential Dynamic Microscopy of Bacterial Motility, PRL 106, 018101, 2011.[2] Wilson LG, Li M, Schwarz-Linek J, Martinez VA, Arlt J and Poon WCK, High-throughputmeasurement of E. coli body and flagellar rotation, in preparation.[3] Schneider WR and Doetsch RN, Effect of Viscosity on Bacterial Motility, J. Bacter, 117, 701(1974)22