Isolation and Identification of Nitrite-Oxidizing Microbes

Abstract

Nitrite-oxidizing bacteria (NOB) are Gram-negative microorganisms, which pick up their energy by changing nitrite over to nitrate. Nitrification is a microbially catalyzed process whereby ammonia (NH 3 ) is oxidized to nitrite (NO 2 À ) and thusly to nitrate (NO 3 À). NOB convey the second phase of the nitrification cycle, that of oxidation of nitrite to nitrate. Since the microorganisms liable for nitrification are fundamentally autotrophic, nitrification gives an interesting connection between the carbon and nitrogen cycles. An unadulterated culture of a nitrite-oxidizing bacterium can be gotten by density gradient centrifugation and a conventional dilution technique. For the enrichment of predominant nitrifiers, combination of the most probable number technique followed by the serial dilutions strategy is recommended. In the highest dilutions, nitrite oxidation can be distinguished simply following a while as a result of the slow growth of the nitrite oxidizers.