Background
Nitrates often serve as a source of nitrogen for bacteria. The ability of organisms to reduce nitrates to nitrites and to further reduce nitrite to nitrogen and oxygen is used in various identification schemes.
Most bacteria encountered in the clinical laboratory reduce nitrate and this test is therefore a useful marker for species that do not. These include a number of Gram negative non-fermenters such as Acinetobacter spp., Alcaligenes faecalis and Sphingobacterium spp. The nitrate test is also highly useful for division of mycobacteria where only a minority of species, including Mycobacterium tuberculosis, are able to reduce nitrate.
The test involves preparing a heavy suspension of the test organism in the presence of a nitrate source, following incubation and the addition of reagents A and B the development of a pink or reddish colour is a positive reaction for nitrate reduction. If the result is negative, the addition of the zinc reagent will identify if the test organism has reduced the nitrate to nitrite then reduced the nitrite to nitrogen and oxygen.
Material Safety Data Sheet (En)
