New article in Nature: Discovery of complete ammonia oxidizers (comammox)


Nitrification has always been considered as a two-step process catalyzed by microorganisms oxidizing either ammonia or nitrite. This functional separation has puzzled microbiologists for a century. Holger Daims, Michael Wagner, and a team of researchers from Vienna, Russia, Denmark, and Germany showed now that members of the nitrite-oxidizer genus Nitrospira are capable of complete nitrification and grow by the oxidation of ammonia to nitrate in a single organism. Intriguingly, key functional genes of these 'comammox' Nitrospira were detected in diverse terrestrial and aquatic environments as well as in new metagenomes from wastewater- and drinking water treatment plants. This discovery fundamentally changes our picture of nitrification and likely will have far-reaching implications for future studies on the microbiology of nitrogen cycling.