Bacteria that possess flagella have the ability to move and thus are motile. Live wet mount preparations of a bacterial culture may be viewed under the microscope to determine if an organism is motile. An alternative method, one that is safer when working with potential pathogens, is the motility stab. A sterile, cool inoculating wire is used to obtain inoculum from a pure culture of the test organism. The wire is stabbed into motility stab media approximately two-thirds of the depth of the media. The wire is then pulled out of the media as close as possible to the location where it entered. The tube is incubated for approximately 24 hours and observed for evidence of motility. A non-motile organism will have a clearly defined edge as it grows on the stab line. Motile organisms will be turbid throughout the tube or have fuzzy, diffuse growth at the edges. Some organisms are so motile that the entire tube becomes very turbid (cloudy). Motile and nonmotile bacteria are shown below.

Motility Stab Media