What Methods Can Be Used to Determine Motility?

Motility is determined for nonpathogens with either a wet mount slide or a hanging drop slide. Pathogenic organisms have their motility determined by soft agar stabbing, which is also known as the tube method.

Of all the methods to determine motility, the wet mount slide is the simplest. By placing a few pieces of the organism on a single slide and covering it with glass, it is possible to tell whether or not the organism has any motility along with other factors, such as its arrangement and shape. The hanging drop slide is similar, but instead of observing organisms between two glass slides, the organisms are viewed through a hanging drop of water that is closed inside a chamber.

Because pathogenic organisms are dangerous, an entirely different method must be used to determine their mobility. To determine motility for such organisms, the tube method is used. This method cultures the organisms in a medium, which allows the organisms to move in a manner that is monitored. The pathogenic organisms in the medium that are not motile simply grow and remain in the same place, but motile organisms grow and start to move in a way that creates a form of detectable cloudiness.