Comparative Base Sequence Homologies of the Deoxyribonucleic Acids of Erwinia Species and Other Enterobacteriaceae

Twenty-six strains representing ten species of Erwinia were examined by deoxyribonucleic acid (DNA)-DNA hybridization techniques for relatedness to each other as well as to other members of the family Enterobacteriaceae, including the genera Escherichia, Salmonella, Klebsiella, Shigella, and Proteus. DNA homologies among the different Erwinia specieswere in most cases below 50%, even under nonstringent annealing conditions. In most instances DNA homologies between Erwinia species and Escherichia, Salmonella, Klebsiella, and Shigella species showed about the same amount of relatedness as in Erwinia-to-Erwinia combinations. The molecular hybridization data indicate that the genus Erwinia is a loosely composed group of bacteria that often have no greater affinities to each other than to other enteric bacteria. Furthermore, the data do not support some of the previously proposed taxonomic divisions within the genus Erwinia.