Nitrogen is a critically important nutrient for organisms, including microorganisms. This element is one of the most abundant elemental constituents of eukaryotic tissues and prokaryotic cell walls, and is an integral component of amino acids, proteins, and nucleic acids.

Most plants obtain their nitrogen by assimilating it from their environment, mostly as nitrate or ammonium dissolved in soil water that is taken up by roots, or as gaseous nitrogen oxides that are taken up by plant leaves from the atmosphere. However, some plants live in a symbiotic relationship with microorganisms that have the ability to fix atmospheric nitrogen (which can also be called dinitrogen) into ammonia. Such plants benefit from access to an increased supply of nitrogen.

As well, nitrogen-assimilating microorganisms are of benefit to animals. Typically animals obtain their needed nitrogen through the plants they ingest. The plant's organic forms of...