OLIGONUCLEOTIDE PROBES BASED ON 16S RIBOSOMAL-RNA SEQUENCES FOR THE IDENTIFICATION OF 4 AZOSPIRILLUM SPECIES

Partial sequences of the 16S rRNA molecules of nine strains belonging to four Azospirillum species were used to design species-specific olig onucleotide probes. Azospirillum strains sequences were analyzed and t hree homologous fragments containing 16 nucleotides were determined. T hese three probes were found to be characteristic of A. lipoferum (Al) , A. irakense (Ai), and A, brasilense/amazonense species (Aba) and of few nontarget organisms. The specificity of these three probes was tes ted both against sequences in the GenBank data base and in numerous co lony hybridization experiments. As a few nontarget organisms hyridized with the different Azospirillum probes, the use of these probes in bu lk soil hybridization is not permitted. However, their use together wi th specific isolation techniques is validated.