What is nitrification,nitrogen fixation and denitrification?
Nitrification: Nitrification is the biological oxidation of ammonia with oxygen into nitrite followed by the oxidation of these nitrites into nitrates. Degradation of ammonia to nitrite is usually the rate limiting step of nitrification. Nitrification is an important step in the nitrogen cycle in soil. This process was discovered by the Russian microbiologist, Sergei Winogradsky. The oxidation of ammonia into nitrite is performed by two groups of organisms, ammonia oxidizing bacteria and ammonia oxidizing archaea. Ammonia oxidizing bacteria can be found among the β- and γ-proteobacteria. In soils the most studied ammonia oxidizing bacteria belong to the genera Nitrosomonas and Nitrosococcus. Although in soils ammonia oxidation occurs by both bacteria and archaea, archaeal ammonia oxidizers dominate in both soils and marine environments, suggesting that Crenarchaeota may be greater contributors to ammonia oxidation in these environments. The second step (oxidation of nitrite into nitrat
