RAPID DIFFERENTIATION, BY POLYAMINE ANALYSIS, OF XANTHOMONAS STRAINS FROM PHYTOPATHOGENIC PSEUDOMONADS AND OTHER MEMBERS OF THE CLASS PROTEOBACTERIA INTERACTING WITH PLANTS

A total of 58 strains belonging to phylogenetically assigned or unassigned species of the class Proteobacteria, which are mostly phytopathogenic or might interact with plants, were analyzed for polyamines. The strains of the genus Xanthomonas contained spermidine as the main polyamine. Putrescine was the main polyamine of phytopathogenic strains belonging to the Pseudomonas fluorescens complex, which represents the phylogenetically defined nucleus of the genus Pseudomonas. The genera Azotobacter and Azomonas, which include free-living diazotrophic bacteria that also belong to the P. fluorescens complex, had a polyamine pattern like that of the strains belonging to the P. fluorescens complex. Xylophilus ampelinus (formerly called Xanthomonas ampelina) and unassigned phytopathogenic pseudomonads phylogenetically allocated to the beta subclass of the Proteobacteria contained 2-hydroxyputrescine, the specific polyamine of this subclass. The main polyamine in Rhizobium, Bradyrhizobium, and Phyllobacterium strains and misnamed pseudomonads belonging to the alpha subclass of the Proteobacteria was sym-homospermidine, which was also present in "Azotomonas fluorescens."