NITROBACTERIUM

nitrobacterium

(noun) any of the bacteria in the soil that take part in the nitrogen cycle; they oxidize ammonium compounds into nitrites or oxidize nitrites into nitrates

Source: WordNet® 3.1

Etymology

Noun

nitrobacterium (plural nitrobacteria)

Any of the several genera of bacteria in soil that take part in the nitrogen cycle, oxidizing ammonium and organic nitrogen compounds to the more soluble nitrite and nitrate.

Source: Wiktionary