Deoxyribonucleic Acid Base Compositions and Nucleotide Distributions of 65 Strains of Budding Bacteria

Abstract

A total of 65 strains of appendaged or prosthecate, budding bacteria from our culture collection were selected for a study of deoxyribonucleic acid (DNA) base composition and nucleotide distribution. These strains represented 11 genera, including 4 genera of hyphal, budding bacteria which have not been formally described yet. The DNA species were thermally denatured, and absorbance-temperature profiles were recorded. The midpoints, widths, and asymmetries of the melting transitions were determined. When the DNA base compositions and nucleotide distributions were plotted on a dissimilarity map, it became evident that the strains of each genus occupied a distinct area. The distribution of strains within such an area indicated the degree of heterogeneity of a genus. When 16 Hyphomicrobium strains were analyzed, they formed five clusters within their generic area. These clusters correlated well with groups which had been previously established by DNA base composition analyses, by DNA-DNA homology studies, and by numerical taxonomy. Nine of the strains investigated were distinguished by melting profiles which were skewed uniquely to the left.