*2.1.2 Nitrogen fixation*

Biological nitrogen fixation is a biological process that is carried out either by symbiotic or non-symbiotic interactions between microbes and plants. Symbiotic PGPRs, which are most frequently reported to fix atmospheric N2 in soil, include strains of *Rhizobium* sp., *Azoarcus* sp., *Beijerinckia* sp., *Pantoea agglomerans*, and *Klebsiella pneumoniae* [10, 13]. Bio-fixation of atmospheric nitrogen is carried out by genera like *Azospirillum*, *Klebsiella*, *Burkholderia*, *Bacillus*, and *Pseudomonas* [18]. Someone of these species has been reported as endophytes in native maize.
