This test is performed in the identification of organisms such as Pseudomonas and Vibrio cholera

vPrinciple:-

Gelatinase enzyme is secreted by the organisms such as Pseudomonas and Vibrio cholerae which act on gelatin which is liquefied and it is confirmed by placing the test at 4°C for 30 minutes.

v Requirements:- 

Nutrient gelatin medium

1.      Peptone                     : 10.0 g

2.      Beef extract               : 3.0 g

3.      Gelatin                         : 120.0 g

4.      Distilled water            : 1000 ml

Dissolve the solid ingredients in 100 ml of distilled water by heating.

Dispense in 7 ml amounts in screw cap test tubes (15 x 125 mm).

Sterilize by autoclaving at 121°C for 15 minutes

v Procedure:-

         1      Inoculate the medium with test organisms.       

        2.     Incubate at 35-37°C for 72 hours.

    3.     Chill the tubes at 4°C for 30 minutes.

    4      Observe for positive gelatin liquefaction

v Observations:-

1. Medium in fluid state: Positive test

2.  Medium in solid state: Negative test

v  Quality control:-

 Use  following microorganisms to confirm the reliability of reagents:

 Positive control        : Pseudomonas aeruginosa

 Negative control      : E. coli