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BACKGROUND
Gelatin is a type of protein obtained from animal protein collagen. The main use of gelatin is as a solidifying agent in food. The process of gelatin hydrolysis is used for determining bacteria proteolysis or the capability of the bacteria to notice the capability of an organism to produce gelatinase that liquefies the gelatin.
Principle: The whole process takes place in two reactions. The first reaction gelatinase degrade gelatin to polypeptides and then polypeptides is converted to amino acids. Then these amino acids are taken by bacteria and are utilized in the metabolic process.
The objective of this experiment is to test the gelatin liquefaction ability of the bacteria.
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REQUIREMENTS
Sample: Test bacteria (18-24 hours culture)
Medium: Nutrient gelatin medium
Apparatus: Test tubes
Inoculating needle
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PROCEDURE
Take nutrient gelatin medium in a tube and add the test bacteria to it by stabbing. In another tube take nutrient gelatin medium and leave it uninoculated for standard.1 Then incubate both in a incubator for about 2 weeks. Up to then everyday bring out the tubes and keep it in ice bath or refrigerator for about 15-30 min for checking gelatin liquefaction. The purpose of keeping it in refrigerator is because in general gelatin liquefies at 28oC, therefore to confirm that it is liquefying because of the bacteria it is kept at a low temperature in a refrigerator. You can confirm hydrolyzation by tilting the tubes a bit.2 So, if there is complete or partial liquefaction in the tube even after keeping in refrigerator, then gelatin hydrolysis is confirmed.3
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CONCLUSION
For proteolysis activity of bacteria, it is one of the important experiment.
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REFERENCES
- Clarke SKR. A simplified plate method for detecting gelatin-liquefying bacteria. J Clin Pathol. 1953;6 :246–8.
- Difco Laboratories. 2009. Difco & BBL manual: manual of microbiological culture media, 2nd ed, p 402–403. Becton Dickinson and Comp any, Sparks, MD.
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Greene RA, Larks GG. A quick method for the detection of gelatin liquefying bacteria. J Bacterial. 1955;69:224.
