Azospirillum

Azospirillum is a Gram-negative, microaerophilic, non-fermentative and nitrogen-fixing bacterial genus from the family of Rhodospirillaceae.

Azospirillum are aerobic, but many can also function as microaerobic diazotrophs, meaning, under low oxygen conditions, they can change inert nitrogen from the air into biologically usable forms.

[9] In Brazil, during the 1970s, similar strains of this species were found associated with the roots of grain plants by scientists led by Dr. Johanna Döbereiner.

[8] Azospirillum are found in freshwater[8] and soil habitats, especially in close relationships with plant roots.

[12] In addition to vascular plants, the growth of the algae Chlorella vulgaris was positively affected by the presence of Azospirillum.

In 2009, the first commercial inoculants containing Azospirillum came on the market, and by 2018, over 3 million doses were applied annually to crops by farmers, mainly in South America.

[15] Azospirillum also make antioxidants that protect the plant roots from stresses due to drought and flooding.

When accessing a phylogenetic tree with all Azospirillum genomes, it is possible to identify two monophyletic groups, one harboring exclusively A. brasilense strains and another the remaining species.