The purpose is to see if the microbe can use the protein gelatin as a source of carbon and energy for growth. Use of gelatin is accomplished by the enzyme gelatinase .<\/p>\n\n\n\n
A medium containing gelatin is used. The presence of gelatinase is detected by the addition of saturated ammonium sulfate after a streak plate has been allowed to grow overnight. The ammonium sulfate forms a cloudy precipitate in the medium when it reacts with the gelatin. Gelatinase activity is visible where clear zones in the cloudy precipitate are found, indicating the gelatin has been hydrolyzed.<\/p>\n\n\n\n
An example for Staphylococci might be Stone Gelatin Agar (also known as Staphylococcus Medium 110). But 3% gelatin can be added to other media to allow detection in other microbes. <\/p>\n\n\n\n
An inoculum from a pure culture is streaked for isolation on an agar plate containing 3% gelatin. The streak plate is incubated at 35-37 C for 24 hours, at which time saturated ammonium sulfate is added to enable interpretation of results.<\/p>\n\n\n\n
Ammonium Sulfate (saturated).<\/p>\n\n\n\n
To view the gelatinase test in VUMIE Online\u00a9 Online Lab, complete the following steps:<\/p>\n\n\n\n
1. Open the Tests link above the Virtual lab and select the Gelatinase Video<\/a>.<\/p>\n\n\n\n 2. Press the Play button to watch the video showing the test being performed.<\/p>\n\n\n\n 3. Observe the results. If the bacterium possesses gelatinase, clear halos will surround the colonies of the microbe. A negative culture will not have clear halos.<\/p>\n\n\n\n 4. Record the test result observed.<\/p>\n\n\n\n
\n\n\n\nVUMIE is the flight simulator of microbiology labs.<\/h2>\n\n\n\n