Nitrate Broth is recommended as an aid in the identification of aerobic and facultative anaerobic gram-negative microorganisms by means of the nitrate reduction test.

• Basal medium containing potassium nitrate
• Addition of zinc dust is used to detect unreduced nitrate
• Organisms derive oxygen from nitrate through anaerobic respiration

The formation of nitrogen gas, an end product typical of certain organisms, is evidenced by displacement of the medium from the Durham tube by the gas produced.