Melanie Pearson, Ph.D. (Mobley Laboratory), Research Assistant Professor, Department of Microbiology and Immunology, University of Michigan Medical School
A common cause of urinary tract infections, especially in catheterized patients, is a bacterial species called Proteus mirabilis. The bacterium was named after the Greek sea god, Proteus, who was able to change shape to avoid capture. This is an apt name, since P. mirabilis regularly changes shape on solid surfaces, from a short rod-like form to a very long, flexible rod covered with thousands of whip-like flagella that bestow the ability to swarm. Because of this shape-shifting behavior, P. mirabilis produces a distinctive bullseye pattern on an agar plate, due to periodic waves of migration separated by consolidation. In this image, a violet dye has been added, with the double effect of making the bacteria easier to see as well as changing the appearance of the swarm. The result is a slow-growing swarm that resembles roots and branches. Understanding the mechanisms that underlie this swarming behavior could help us understand the behavior of these bacteria in the context of urinary tract infections.