Majority of Rhizobium species form an endosymbiotic nitrogen-fixing association with roots of legumes such as peas, soybeans and alfalfa, and Parasponia. This relationship leads to the establishment of specialized structures called nodules. In these structures the bacteria are able to convert atmospheric nitrogen into ammonia, a process called nitrogen fixation. Rhizobium-legume symbioses are of great ecological and agronomic importance, due to their ability to fix large amounts of atmospheric nitrogen. Rhizobium inoculation has shown beneficial effects on nodulation, grain yield, and protein content of peas. A natural endophytic association between PGPR Rhizobium and rice was recently observed in the Nile delta region where rice is grown since antiquity, in rotation with the Egyptian berseem clover. The lipopolysaccharides (LPS) of Rhizobium induced systemic resistance in potato roots against the cyst nematode Globodera pallida.Rhizobium has also been identified as a contaminant of DNA extraction kit reagents and ultrapure water systems, which may lead to its erroneous appearance in microbiota or metagenomic datasets. Non-rhizobia members of Rhizobium have been reported from various environments including ground water, soil, and river and lake water.