Denitrifying bacteria form a necessary part of the process known as denitrification as part of the nitrogen cycle which consists of the ongoing processes that Nitrogen has to undertake as it is the largest gas compound in the atmosphere. Their primary purpose being to metabolise nitrogenous compounds, with the assistance of the nitrate reductase enzyme, to turn oxides back to nitrogen gas or nitrous oxides for energy generation.
The process of denitrification lowers the fertility rate of reproduction of the soil and thus is less common in areas where the land is rather well-cultivated. But this loss of nitrogen to the atmosphere can eventually be regained via introduced nutrients, as part of the nitrogen cycle. Some nitrogen may also be fixated by species of nitrifying bacteria and the cyanobacteria.
Denitrification also becomes the key pathway for dissimilative nitrate reduction, which is the process in which nitrates are reduced from the soil, the former being highly toxic for living organisms. Denitrification tends to produce large amounts of by-products.
The most common denitrification process is basically outlined below, with the nitrogen oxides being converted back to gaseous nitrogen (as opposed to that of nitrifying bacteria):
+ 10 e−
+ 12 H+
+ 6 H2
The result is one molecule of nitrogen (consisting of two atoms) and six molecules of water. Denitrifying bacteria are a part of the N cycle, and consists of sending the N back into the atmosphere
Denitrifying bacteria themselves include several species of Pseudomonas, Alkaligenes , Bacillus and others. By their activity the losses of nitrogen into the atmosphere is roughly balanced by that which is released into the soil by nitrifying bacteria, forming a relatively balanced cycle.