Assessment of Phenotypic Variability in Erwinia stewartii Based on Metabolic Profiles

One hundred twenty-four bacterial isolates originating from sweet corn or corn flea beetles in the northeastern, midwestern, and mid-Atlantic United States were verified as Erwinia stewartii (Pantoea stewartii subsp. stewartii) and characterized phenotypically by their respiratory response to 91 carbon sources. The unweighted pair group method of averages (UPGMA) was used to construct a dendrogram that revealed homogeneous metabolic profiles at 93% similarity. Two-thirds of the isolates formed 18 separate groups, each sharing the same metabolic profile. One-third of the isolates had distinct metabolic profiles. Most groups shared either isolation source, geographical location, and/or year of isolation. Members of some groups persisted through time and had been isolated from diverse geographical locations. Four representative strains of the proposed Pantoea stewartii subsp. indologenes were also characterized; their metabolic profiles were most similar to those of Erwinia herbicola (Pantoea agglomerans).