About this test
What is the purpose of the test?
Some bacteria have the ability to propel themselves through liquids by means of flagella (flagellum = singular). These long fibers of protein are found on many bacteria, including most supported by this simulation. However, not all bacteria are able to “swim”, even if they have flagella . The purpose of this test is to see if the microbe can “swim” by means of flagella .
How is motility determined?
Motility can be detected in a couple of ways. For this simulation, motility will be monitored by means of microscopically observing the bacteria in a wet mount .
What medium is used?
No special media are required for this test, although use of broth cultures is preferred. Only fresh cultures (18-24 hr) of the bacterium grown on a nonselective medium should be used for preparing the wet mount to be observed.
How is the test performed?
Fresh growth (not over 24 h old) should be used for preparing the wet mount . The growth is transferred to a drop of water or saline on a microscope slide, mixed, and a cover slip is added. For VirtualUnknown™ Microbiology, the work has been done for you, and a video displays the scene under the microscope. Motility is interpreted using high dry magnification to locate the bacteria within the drop of water. If they swim randomly and “against the current” of water streaming across the slide surface, they are positive for motility . If they seem to be buffeted around, all moving the same direction and at the same speed, there is no motility. Instead, this type of movement is the result of the bacteria being knocked about by water molecules, called Brownian movement .
What reagents are added?
Performing this test in the VUMIE Online lab
To view the motility test in VUMIE Online© Online Lab , complete the following steps:
1. Open the Tests link above the Virtual lab and select the Motility Video.
2. Press the Play button to watch the video. A short video clip showing microscopic observation of a motility test for the unknown organism will play.
3. Observe the results. If the bacteria are motile, cells from those present will swim in purposeful, random directions. If the bacteria are non-motile, they will not swim in this manner. If there is movement, non-motile cells will be buffeted around by water molecules in an example of Brownian movement.
4. Record the test result observed .