These 4 IMViC tests (actually 6 tests if you include motility and H2S) constitute, perhaps, the most critical tests THE INOCULATION PROCEDURES: Indole test . The four reactions are: Indole test, Methyl Red test, Voges Proskauer test and Citrate Procedure: Bacterium to be tested is inoculated in peptone water, which . In IMViC test there are four biochemical tests and this test are carried out IMViC test is carried out to identify members of the Procedure.

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Others produce acetoin but quickly metabolize it to something else, also scoring as negative. V- Voges- Proskauer test. Escherichia coli is Indole positive, Enterobacter cloacae is negative.

Abstract An agar plate method was developed for the performance of the IMVic indole, methyl red, Voges-Proskauer, and citrate tests in lieu of the conventional tubed liquid media.

After adding both reagents, the tube is shaken vigorously then allowed to sit for minutes. Xylene The composition of media and reagents 1.

After incubation, add drops of xylene in tubes and shake vigorously and keep the tubes still so that two layers get separated. The micro-organisms from Provedure family carry out fermentation pathway they metabolise glucose to pyruvic acid to formic acid and this formic acid formation is called formic acid fermentation process.

Tests with 87 cultures, representing 7 genera in the family Enterobacteriaceae, were completed with typical correct IMVic patterns for all cultures within 48 h. Fermentation of sugars also lowers the pH which inhibits tryptophanase activity.


Archived from the original on The citrate agar is green before inoculation, and turns blue as a positive test indicator, meaning citrate is utilized.

This page was last edited on 29 Augustat A yellow color B Examples: Incubate imivc at 37 degrees C. National Center for Biotechnology InformationU. Ease of performance and simplification of the test were achieved by inoculating all four media simultaneously from a single colony single inoculum on eosin-methylene blue agar.

imvlc To carry out the citrate utilization test to determine the ability of a bacterial cell to utilize citrate. Originally the paired MR-VP tests were used to distinguish between members of the family Enterobacteriaceae, but now they are used to characterize other groups of bacteria including Actinobacteria.

M R requires an extended incubation period. We will inoculate a single tube for MR-VP test, and then split the contents into the two tubes to perform two tests at a later date. Here in V-P test after fermentation, the medium is treated with alpha-naphthol and KOH solution and due to the addition of this acetoin is oxidised to diacetyl. Result Formation of a deep blue colour imviv positive citrate utilization test and the test culture has an ability to utilize citrate.

We will go through these tests one by one.

For carrying out the citrate utilization test the test culture should be exposed to a medium which contains citrate as a sole source of carbon and energy. Butanediol fermentation — This fermentation is carried out in Bacillus, Enterobacteriaceae, Serratia. In general, there are two types of formic acid fermentation pathway and they are: Bromothymol blue is yellow at acidic pH and blue at alkaline pH.


For carrying out this test we need citrate agar that contains, ammonium phosphate as a source of nitrogen, Sodium citrate as the source of carbon and bromothymol blue as a pH indicator. Upon further incubation, fermentors that do not perform mixed acid fermentation will metabolize the acidic intermediates to mainly neutral products such as acetoin which will fail to overcome the buffers in the media.

Am J Clin Pathol.

IMViC – Wikipedia

Differential Reactions in the Colon Group of Bacteria. These IMViC tests are useful for differentiating the family Enterobacteriaceaeespecially when used alongside the Urease test. In fact, Pos et. IMViC test is carried out to identify members of the Enterobacteriaceae family.

Methyl Red (MR) Test- Principle, Procedure and Result Interpretation

Thus the formation of pink colour indicates the presence of acetoin and conforms Butanediol fermentation and indicates V-P test as positive. We use cookies to ensure that we give you the best experience on our website.

Now when we compare this two fermentations process, mixed acid fermentation produces more acidic products and it acidifies the incubation media. If the bacteria has the ability to utilise glucose with production of a stable acidthe colour of the methyl red changes from yellow to redwhen added into the broth culture.

This test is often discussed as being positive if the tube turns blue anywhere in the tube and negative if it remains green.