GELATIN LIQUIFACTION TEST
AIM:
To determine the
ability of an organism that produce gelatinases.
PRINCIPLE:
Gelatin hydrolysis test is used
to detect the ability of an organism to produce gelatinase (proteolytic enzyme)
that liquefy gelatin. Gelatin is a protein derived from the connective tissues
of vertebrates, that is, collagen. It is produced when collagen is boiled in
water. Gelatin hydrolysis indicates the presence of gelatinases. This
process takes place in two sequential reactions.In the first reaction,
gelatinases degrade gelatin to polypeptides
Then, the polypeptides are further converted
into amino acids.
.bmp)
The bacterial cells can then take up these
amino acids and use them in their metabolic processes.
Procedure /Method of Gelatin hydrolysis test:
1. A heavy inoculum of
test bacteria is inoculated (18- to 24-hour-old) by stabbing 4-5 times on the
tube containing nutrient gelatin medium.
2.
The inoculated tube is incubated along with an uninoculated medium at
35°C, for up to 2 weeks.
3. the tubes daily from
the incubator shall be removed and placed in ice bath or refrigerator
(4°C) for 15-30 minutes (until control is gelled) every day checked for
gelatin liquefaction.(Gelatin normally liquefies at 28°C and above, so to
confirm that liquefaction was due to gelatinase activity, the tubes are
immersed in an ice bath or kept in refrigerator at 4°C).
4.
The tubes are tilted to
observe if gelatin has been hydrolyzed.
Expected
results
Positive: Partial or total
liquefaction of the inoculated tube (uninoculated control medium must
be completely solidified) even after exposure to cold temperature of ice
bath or refrigerator (4°C)
Negative: Complete
solidification of the inoculated tube even after exposure to cold temperature
of ice bath or refrigerator (4°C)
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