16S-RIBOSOMAL-RNA GENE SEQUENCE ANALYSES AND INTERGENERIC AND INTRAGENERIC RELATIONSHIPS OF XANTHOMONAS SPECIES AND STENOTROPHOMONAS-MALTOPHILIA

The nearly complete, PCR-amplified, 16S rRNA gene sequences have been determined from the representative type strains of eight xanthomonad p hena, including six validly described species of the genus Xanthomonas and Stenotrophomonas maltophilia. Pairwise sequence comparisons and p hylogenetic analysis demonstrated that the xanthomonads comprise a mon ophyletic lineage within the gamma-subclass of the Proteobacteria. Alt hough the genus Xanthomonas was observed to comprise a cluster of very closely related species, the observed species-specific primary sequen ce differences were confirmed through sequencing additional strains be longing to the respective species.