Swarming motility of Pseudomonas aeruginosa transposon mutant A12c on minimal medium with glutamate as nitrogen and carbon source and 0.1% Gelzan after 24 hours incubation at 30°C (image by Anne E. Mattingly, Nachiket G. Kamatkar and Joshua D. Shrout, University of Notre Dame, USA); image modified by MIC. The cover is published under the Creative Commons Attribution (CC BY) license.