Genus Erwinia: Numerical Analysis of Phenotypic Features

API 20E and API 50CHE systems (72 phenotypic tests) were applied to a total of 529 strains, including 421 strains belonging to 21 different Erwinia species, 66 Enterobacter agglomerans strains, 18 Escherichia adecarboxylata strains, and 24 strains of 16 other enterobacteria. The results were analyzed numerically by using the Gower similarity coefficient and the unweighted average linkage method. The named Erwinia strains were distributed over 27 phena, some of which also contained strains received as Enterobacter agglomerans. Strains of Erwinia amylovora, Erwinia chrysanthemi, Erwinia cypripedii, Erwinia mallotivora, Erwinia nigrifluens, Erwinia paradisiaca, Erwinia quercina, Erwinia rubrifaciens, Erwinia salicis, Erwinia stewartii, and Escherichia adecarboxylata constitute separate phena. Erwinia carotovora, Erwinia chrysanthemi, and Erwinia rhapontici are heterogeneous, but distinct from each other and from the other phena. The type strains of Erwinia herbicola, Enterobacter agglomerans, and Erwinia milletiae fall into one phenon, and strains of Erwinia ananas and Erwinia uredovora are in a single phenon. Obviously misnamed Erwinia herbicola and Enterobacter agglomerans strains can be assigned to other species, such as Erwinia cypripedii, Erwinia ananas, Erwinia rhapontici, Rahnella aquatilis, Enterobacter sakazakii, Escherichia adecarboxylata, and Serratia marcescens or to as-yet-unnamed phena. Three Erwinia carnegieana strains, but not the type strain, form one phenon. Erwinia dissolvens and Erwinia nimipressuralis should be allocated to Enterobacter. Our results confirm the heterogeneous taxonomic structure of the genus Erwinia.