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Ammonification -

Plants synthesize organic nitrogenous compounds which serve as the source of nitrogen for animals. The organic nitrogenous compounds are assimilated by animals. During this process they are hydrolyzed to a greater or lesser extent, but remain largely as reduced organic compounds. Proteins and other nitrogenous compounds of living organisms find their way to the soil either through excretion or decomposition of dead organisms by microorganisms.

These compounds are hydrolyzed by various proteolytic enzymes to amino acids and similar compounds. The amino group (-NH2) is split off to form ammonia (NH3) Release of ammonia from organic nitrogenous compounds is termed ammonification.

Decomposition

Much of the nitrogen in organic compounds remains in plant and animal tissues. This locked up nitrogen is released only on the death of the organisms. On the death of a plant or animal, the remains are immediately attacked by microorganisms.

The first step in ammonification is the hydrolysis of proteins and nucleic acids. This results in the liberation of amino acids and nitrogenous bases, respectively. These simpler compounds are then metabolized further by aerobic respiration or fermentation.

Proteolytic enzymes are elaborated by clostridia, many fungi and actinomycetes, and to a lesser degree by Pseudomonas, Bacillus and Proteus species. The ultimate products of proteolysis are amino acids. Under aerobic conditions, amino acids undergo oxidative deamination and liberate ammonia.