Question

How are they different (especially wells IND, VP, and TDA) for each of the bacteria.

Answer 1

These test consists of microtubes containing dehydrated substrates. These tests are inoculated with a bacterial suspension that reconstitutes the media. During incubation, metabolism produces color changes that are either spontaneous or revealed by the addition of reagents.

TDA test for tryptophane deaminase.

A reddish brown color in TDA indicates a positive reaction. Wait for 10 minutes after adding reagents from the kit into VP1 and VP2. Consider a red or pink color as positive and a pale pink color appearing after 10 minutes as negative.

IND test for indole production.

Indole as an end up product may be detected by the reaction with JAMES reagent. Pink colour change indicates a (+) positive reaction. IND test should be performed last due to possible interference of released gaseous products with other tests.

VP Voges Proskauer test for acetoin production

Acetoin is detected via colour change reaction with VP1 and VP2.

A pink or red color indicates a positive reaction. If a slightly pink color appears after 10 minutes, the reaction should be considered negative.