This slant is recommended for detection of nitrate reducing bacteria. The presence of nitrites can be detected by the addition of 0.5 ml each of sulphanilic acid (R015) and a-naphthylamine solution (R009). Members of Enterobacteriaceae characteristically reduce nitrate to nitrite which reacts with sulfanilic acid and N, N- dimethyl-1-naphthylamine to produce the red colour. This reaction is known as Griess reaction.