PHYLOGENY OF THE GENUS AZOSPIRILLUM BASED ON 16S RDNA SEQUENCE

The 16S rDNA of 17 strains of Azospirillum, 14 assigned to one of the known species A. amazonense, A. brasilense, A. halopraeferens, A. irak ense and A. lipoferum, and the other three of uncertain taxonomic posi tion, was sequenced after polymerase chain reaction amplification and analysed in order to investigate the phylogenetic relationships at the intra-generic and super-generic level. The phylogenetic analysis conf irms that the genus Azospirillum constitutes a phylogenetically separa te entity within the cr subclass of Proteobacteria and that the five s pecies are well defined. A. brasilense and A. lipoferum are closely re lated species and form one cluster together with A. halopraeferens; th e pair of species A. amazonense and A. irakense forms a second cluster in which Rhodospirillum centenum is also placed.