Phylogenetic analysis of Erwinia species based on 16S rRNA gene sequences.

The phylogenetic relationships of the type strains of 16 Erwinia species were investigated by performing a comparative analysis of the sequences of the 16S rRNA genes of these organisms. The sequence data were analyzed by the neighbor-joining method, and each branch was supported by moderate bootstrap values. The phylogenetic tree and sequence analyses confirmed that the genus Erwinia is composed of species that exhibit considerable heterogeneity and form four clades that are intermixed with members of other genera, such as Escherichia coli, Klebsiella pneumoniae, and Serratia marcescens. Cluster I includes the type strains of Erwinia herbicola, Erwinia milletiae, Erwinia ananas, Erwinia uredovora, and Erwinia stewartii and corresponds to Dye's herbicola group. Cluster II consists of Erwinia persicinus, Erwinia rhapontici, Erwinia amylovora, and Erwinia cypripedii. Cluster III consists of Erwinia carotovora subspecies and Erwinia chrysanthemi and is characterized by the production of pectate lyases and cellulases. Erwinia salicis, Erwinia rubrifaciens, and Erwinia nigrifluens form the cluster that is most distantly related to other Erwinia species. The data from the sequence analyses are discussed in the context of biochemical and DNA-DNA hybridization data.