Ethanol represses swarming and stimulates biofilm formation by <i>P. aeruginosa</i>.

<p><b>A</b>. <i>P. aeruginosa</i> strain PAO1 attachment to the bottom of a polystyrene plastic well after 6 hours in medium with and without 1% ethanol (EtOH). <b>B</b>. <i>P. aeruginosa</i> strain PA14 attachment to plastic as assessed by quantification of microcolonies per field in wells containing medium with or without ethanol for 7 h. Error bars represent the standard deviation (p<0.01 as determined by a student's t-test, N = 12). <b>C</b>. <i>P. aeruginosa</i> strain PA14 swarming in the absence and presence of 1% ethanol. Images are representative of results in more than ten independent experiments.