1. Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, USA
2. Division of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, Massachusetts 02138, USA
3. The Rowland Institute at Harvard, 100 Edwin H. Land Boulevard, Cambridge, Massachusetts 02142, USA
4. Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Avenue, Cambridge, Massachusetts 02138, USA

Correspondence to: George M. Whitesides¹ Correspondence and requests for materials should be addressed to G.M.W. (Email: gwhitesides@gmwgroup.harvard.edu).

Abstract

The motion of peritrichously flagellated bacteria close to surfaces is relevant to understanding the early stages of biofilm formation and of pathogenic infection^{1, 2, 3, 4}. This motion differs from the random-walk trajectories⁵ of cells in free solution. Individual Escherichia coli cells swim in clockwise, circular trajectories near planar glass surfaces^{6, 7}. On a semi-solid agar substrate, cells differentiate into an elongated, hyperflagellated phenotype and migrate cooperatively over the surface⁸, a phenomenon called swarming. We have developed a technique for observing isolated E. coli swarmer cells⁹ moving on an agar substrate and confined in shallow, oxidized poly(dimethylsiloxane) (PDMS) microchannels. Here we show that cells in these microchannels preferentially 'drive on the right', swimming preferentially along the right wall of the microchannel (viewed from behind the moving cell, with the agar on the bottom). We propose that when cells are confined between two interfaces—one an agar gel and the second PDMS—they swim closer to the agar surface than to the PDMS surface (and for much longer periods of time), leading to the preferential movement on the right of the microchannel. Thus, the choice of materials guides the motion of cells in microchannels.

MORE ARTICLES LIKE THIS

These links to content published by NPG are automatically generated.