Question

The IMViC test series differentiates the two groups of coliforms. What are the typical IMViC results for each group of coliforms?

Answer 1

IMViC test include four tests together to separate the types of coliform bacteria.
1: Indole test of IMViC test is done to detect the production of indole from tryuptophan
2: Methyl red test determines the ability of bacteria to carry out mixed acid fermentation.
3: VP test is done to determine the production of acetone and citrate test determines use of sodium citrate as source of carbon.

Indole positive bacteria produce top layer of pink color in while indole negative bacteria do not show this layer.
VP test gives reg colored complex for bacteria that form acetone.
VP positive bacteria give pink color with methyl red test while MR positive bacteria give red color with methyl red test. VP negative bacteria do not give pink color with methyl red test. MR negative bacteria give yellow or orange color with methyl red.
Citrate positive bacteria give deep blue color in citrate utilization test