1) Bacteria genus 2) Genus nitrobacter 3) Rod-shaped soil bacteria 
Nitrobacter is a genus of mostly rod-shaped, gram-negative, and chemoautotrophic bacteria. Nitrobacter plays an important role in the nitrogen cycle by oxidizing nitrite into nitrate in soil. Unlike plants, where electron transfer in photosynthesis provides the energy for carbon fixation, Nitrobacter uses energy from the oxidation of nitrite ions,...
(from the article `nitrifying bacterium`) ...groups: bacteria that convert ammonia to nitrites (Nitrosomonas, Nitrosospira, Nitrosococcus, and Nitrosolobus) and bacteria that convert nitrites ... ...gas. The conversion of ammonia or organic amines to nitrate is accomplished by the combined activities of the aerobic organisms Nitrosomona...
A genus of gram-negative, rod-shaped bacteria that oxidises nitrites to nitrates. Its organisms occur in aerobic environments where organic matter is being mineralised. ... (12 Dec 1998) ... 
[n] - rod-shaped soil bacteria
genus Nitrobacter noun rod-shaped soil bacteria