Ammonification is the process of release of ammonia from organic nitrogenous compound by proteolytic enzymes, which are included by Bacillus and Proteus species.
Clostridium and some species of Serratia, Pseudomonas are denitritying bacteria.
Azotobacter fix nitrogen by means of nitrogenase enzyme (an important enzyme complex that is present in those micro-organisms that are capable of fixing atmospheric nitrogen). Nitrogenase catalyses the conversion of atmospheric nitrogen into ammonia, which can be used to synthesize nitrites, nitrates or amino acids.
Nitrosococcus brings about nitrification, ie, oxidation of ammonia to nitrite. 2NH3+3O2⟶2NO2−+2H++energy.