EN
From the seven species: A. amazonense, A. halopraeferens, A. largimobile, A. irakense and A. doebereinerae, that had been described, A. brasilense and A. lipoferum were isolated all over the word from soil and the roots a variety of grasses and cereals. These bacteria are aerobic nonfermentative chemoorganotrophs. They are Gram negative, the cells are vibrioid to S-shaped, mobile in liquid media by a polar flagellum. On solid media, A. brasilense, A. lipoferum and A. irakense have the lateral flagellae. In case of Azospirillum spp. the formation of cyst-like structures in old cultures was described. They contain granules of poly-ß-hydroxybutyrate (PHB). Azospirillum spp. synthesize exopolysaccharides and capsular polysaccharides. The G + C content in DNA varies between 64 and 70 mol%. Their optimum growth temperature ranges from 28° to 41°C. In general, the bacteria of Azospirillum genus utilize a variety of sugars, alcohols and organic acids as carbon sources. A. irakense grows with pectin as the sole carbon source. Autotrophic growth under aerobic conditions, with H₂ as the energy source has been demonstrated for A. lipoferum. Azospirillum spp. can utilize the ammonia and nitrate, most strains of A. brasilense and A. lipoferum are denitrifiers, whereas A. amazonense and A. irakense are reported to be unable to denitrify. From other physiological properties, they can produce siderophores, phytohormones and other plant growth-promoting substances.