High-grade Indole Nitrate Medium (Tryptone Nitrate Medium) is supplied by Micromaster. It is available in the form of a cream to yellow homogenous free-flowing powder with a pH in the range of 7.0 to 7.4. For maximum efficiency, it must be stored below 30C in a tightly closed container.

Quantity provided: 100g /pack

Indole Nitrate Medium (Tryptone Nitrate Medium) is used for identification of microorganisms on the basis of nitrate reduction and indole production. This medium supports the growth of aerobes, microaerophiles, and facultative as well as obligate anaerobes, due to the nutritive content. However, Indole Nitrite Medium should not be used for detecting indole production by members of the Enterobacteriaceae.

Casein enzymic hydrolysate contains tryptophan which, when acted upon by certain microorganisms, results in the production of indole. Potassium nitrate acts as the substrate for determining nitrate reduction by microorganisms. Duplicate tubes of Indole Nitrate Medium may be inoculated and tested for the presence of nitrates or indole after incubation for various lengths of time. Nitrate test is performed by addition of 0.5 ml each of Sulphanilic Acid and alpha Naphthylamine. The development of pink colour indicates nitrate reduction. The colour develops due to the presence of nitrite generated from the reduction of nitrate. When nitrate is further reduced to ammonia, no colour develops. Indole production can be tested by the addition of Kovacs Reagent or Ehrlich reagent. The formation of deep red colour in the reagent layer after gentle agitation indicates positive indole test. Indole Nitrate Medium is not recommended for indole test in coliform and other enteric bacteria, as they reduce nitrate to nitrite, which prevents the detection of indole.