Subjective Synonymy of Erwinia herbicola, Erwinia milletiae, and Enterobacter agglomerans and Redefinition of the Taxon by Genotypic and Phenotypic Data

Abstract

The type strain Enterobacter agglomerans ATCC 27155 was examined for deoxyribonucleic acid (DNA) relatedness to 54 strains of the “Erwinia herbicola-Enterobacter agglomerans complex,” to 23 strains of other Erwinia and Enterobacter species, and to 50 reference strains of 49 different species in other genera of the family Enterobacteriaceae. The DNA-DNA hybridization values (at the optimal renaturation temperature; nitrocellulose filter method) showed that 24 strains were highly related to Enterobacter agglomerans ATCC 27155T (62 to 97% DNA relatedness) and formed a genotypic group provisionally called DNA hybridization group 27155. These strains were received as Enterobacter agglomerans (including strains of DNA hybridization groups V and XIII [D. J. Brenner, G. R. Fanning, J. K. Leete Knutson, A. G. Steigerwalt, and M. I. Krichevsky, Int. J. Syst. Bacteriol. 34:45-55, 1984]); as Erwinia herbicola, including the type strain NCPPB 2971; as Erwinia milletiae, including the type strain NCPPB 2519; and as yellow-pigmented Enterobacter strains. Numerical analysis of the protein electropherograms of these strains revealed the existence of seven protein electrophoretic groups, each showing a characteristic protein pattern. These seven groups separated at an infraspecific level and allowed assignment of 37 additional strains, received as Enterobacter agglomerans, Erwinia herbicola, and Erwinia milletiae, to DNA hybridization group 27155. The resulting group hybridized below 55% DNA relatedness with all remaining phenotypic or genotypic groups of the “Erwinia herbicola-Enterobacter agglomerans complex” and below 57% DNA relatedness with other Erwinia and Enterobacter species. DNA binding with 49 other species of the family Enterobacteriaceae was less than 38%. Since DNA hybridization group 27155 contains the type strains of Erwinia herbicola, Erwinia milletiae, and Enterobacter agglomerans, these species names are subjective synonyms, and the specific epithet agglomerans has priority. Further genotypic studies with several closely related genera are required for final placement of this species in a genus. The description of Enterobacter agglomerans, Erwinia herbicola, and Erwinia milletiae is emended.