Gelatin liquefaction: This media is used to test if bacteria can digest the protein gelatin. To digest gelatin, the bacteria must make an enzyme called gelatinase. To inoculate this media, use a transfer needle to stab the gelatin. After incubating the inoculated media for at least 48 hrs, transfer the tube into a refrigerator. The tube should be completely chilled prior to observation. If the media is solid after refrigeration then the test is negative (the bacteria did not digest gelatin). If the media is liquefied even after refrigeration, then the test result is positive, the bacteria is able to digest gelatin.