[Perspective] The do-it-all nitrifier

With numerous amendments to the microbial nitrogen cycle over the past two decades, it seems at times that nothing is certain. Yet one aspect of the nitrogen cycle seemed clear: that the labor of nitrification—the oxidation of ammonia (NH3) to nitrite (NO2−) and ultimately nitrate (NO3−)—is divided between two separate groups of microorganisms. Sergei Winogradsky first showed this in the late 1800s when he isolated the organisms responsible for the two steps of nitrification, ammonia oxi