- Also known as Biochemical test
- It is used for differentiate bacteria belonging to family Enterobacteriaceae. Eg- E.coli , Enterobacter aerogens
- IMViC test is group of four different types test.
- Each letters in IMViC test stands for individual test
M - methyl red test
V - voges-proskauer test
C - Citrate test
1-INDOLE TEST
. Tryptophan Media
. Kovac's reagent
. Red/Pink colour appers at the top of tube after addition of kovac's reagent.
Principle:-
- Bacterial culture react with tryptophan media in the +nce of tryptophanase enzyme {kovac's reagent} gives indole(red colour) along with ammonia and amino acids .
REACTION:-
Tryptophan --------Tryptophanase enzyme------> Indole + amino acids +ammonia(NH3)
- A positive indole result indicates due to appear red layer at the lop of tube.
PROCEDURE :-
Firstly bacterial suspension with agar media and tryptophan incubate 2-3days at 37°c in incubator
Then after incubation kovac's reagent is added
. A positive indole result indicates due to appear red layer at the lop of tube.
. A negative indole result indicates due to lack of colour change at the top of tube.
Eg:- E.coli gives positive test , E.Aerogenosa gives negative test.
2:-METHYL RED TEST
It is a test for acid formation
MR-VP media
Red colour appear
Principle:-
. Bacterial suspension react with MR-VP media and gives acid after fermentation .
REACTION:-
Glucose + water -------------> organic acid (red colour)
Procedure:-
. Firstly take bacterial suspension with methyl red broth(MR) in a tube.
. Then tube incubated for 2-3days at 37°c in incubator for growth of bacteria.
A positive results acid formation after fermentation gives red colour.
Eg:- E.Coli gives positive methyl red test, E.Aerogenosa gives negative test (yellow colour).
