Azospirillum Physiological properties, mode of association with roots and its application for the benefit of cereal and forage grass crops

The free-living nitrogen-fixing bacterium Azospirillum species formerly known as Spirillum lipoferum (Beijerinck) has been described in detail by Tarrand et al., 1978. Based on DNA homology studies, two species of the genus have been characterized: Azospirillum brasilense and A. lipoferum. DNA composition of the genus is 69—71% G + C. The colonies are pink-red, drying out and turning rough with folded, wavy surfaces. Cells of Azospirillum are highly motile, half curved (vibroid), gram negative rods, having a diameter of 1.0 pm, with a polar flagellum when grown on liquid medium. Lateral flagella with shorter wavelengths could be observed in A. brasilense growing in agar medium. Cells contain prominent intracellular granules of poly-3- hydroxybutyrate.