Nitrobacter vulgaris is a rod-shaped, Gram-negative, and a chemoautotrophic bacterium. It plays an important role in the nitrogen cycle by oxidizing nitrite into nitrate in soil. It cannot tolerate highly alkaline (NH<sub>4</sub>+) conditions.
NO<sub>2</sub>- + 1/2O<sub>2</sub> -> NO<sub>3</sub>-