Nitrogen cycle

Nitrification involves the oxidation of NH3 to NO3^- (nitrite), and is the opposite of denitrification. This is a two step process: 1. NH3 + O2 → NO2^- + 3H⁺ + 2e^- performed by autotrophic bacteria including the genus Nitrosomonas and Nitrosococcus. 2. NO2^- + H2O → NO3^- + 2H⁺ + 2e^- (oxidation of nitrite into nitrate) is chiefly performed by autotrophic bacteria of the genus Nitrobacter. Denitrification reduces the products of nitrification, and is performed by heterotrophic bacteria, including Pseudomonas sp. NO3 → NO2 → NO → N2O → N2 2NO3^- + 10e^- + 12H⁺ → N2 + 6H2O