Edinburgh Research Explorer

Flagellated bacterial motility in polymer solutions

Research output: Contribution to journalArticle

Related Edinburgh Organisations

Open Access permissions

Open

Documents

Original languageEnglish
Pages (from-to)17771-17776
Number of pages6
JournalProceedings of the National Academy of Sciences
Volume111
Issue number50
DOIs
StatePublished - 16 Dec 2014

Abstract

It is widely believed that the swimming speed, v, of many flagellated bacteria is a nonmonotonic function of the concentration, c, of high-molecular-weight linear polymers in aqueous solution, showing peaked v(c) curves. Pores in the polymer solution were suggested as the explanation. Quantifying this picture led to a theory that predicted peaked v(c) curves. Using high-throughput methods for characterizing motility, we measured v and the angular frequency of cell body rotation, Omega, of motile Escherichia coli as a function of polymer concentration in polyvinylpyrrolidone (PVP) and Ficoll solutions of different molecular weights. We find that nonmonotonic v(c) curves are typically due to low-molecular-weight impurities. After purification by dialysis, the measured v(c) and Omega(c) relations for all but the highest-molecular-weight PVP can be described in detail by Newtonian hydrodynamics. There is clear evidence for non-Newtonian effects in the highest-molecular-weight PVP solution. Calculations suggest that this is due to the fast-rotating flagella seeing a lower viscosity than the cell body, so that flagella can be seen as nano-rheometers for probing the non-Newtonian behavior of high polymer solutions on a molecular scale.

    Research areas

  • swimming microorganisms, complex fluids, rheology, non-Newtonian fluids, ESCHERICHIA-COLI, FLOW, MICROORGANISMS, EFFICIENCY, VISCOSITY, RHEOLOGY, FLUIDS, MUCUS

Download statistics

No data available

ID: 21286539