Swarming in Bacteria: A Tale of Plasticity in Motility Behavior

One of the most fascinating sights in nature is to witness certain insects, birds, and fish move together in a very coordinated and precise fashion for food search, to avoid predation and for migration. The collective movement is called swarming. In 1885, Gustav Hauser, a German pathologist discovered collective movement in a bacterium he later named Proteus mirabilis (Armbruster and Mobley in, Nat Rev Microbiol 30: 186–194, 2013). It was not until 1972 when this mode of bacterial movement was characterized and classified by Henrichsen (Bacteriol Rev 36: 478–503, 1972). Several bacteria are now known to exhibit swarming. Here we describe the how and why of swarming with a focus on plasticity.