Nature Materials 13, 748–755 (2014); published online 11 May 2014; corrected after print 7 January 2016.

In the version of this Article originally published, the fluorescence micrograph in Fig. 3b, the second panel on the lower row erroneously showed a micrograph that corresponded to Escherichia coli instead of Pseudomonas aeruginosa. The correct image is shown below, and this error has been corrected in the online versions of the Article.