Deoxyribonucleic acid relationships among members of the genus Aeromonas.

Polynucleotide sequences among 24 motile and 11 non-motile aeromonads were studied by analysis of deoxyribonucleic acid - deoxyribonucleic acid (DNA-DNA) duplexes with endonuclease S1. In addition, DNA base composition (mole % guanine and cytosine (G + C)) and relative genome sizes were determined for selected strains. Large variations in genome size were found and % GC ranged from 57.1 to 62.9%. On the basis of the strains examined, the Genus Aeromonas consists of two genotypically legitimate groups: a diverse group of motile aeromonads, and the genetically more homogeneous non-motile aeromonads, comprising the species Aeromonas salmonicida. Internal homology groups could not be demonstrated within the motile aeromonads, and significant divergence in related sequences was indicated. This diverse motile group forms the single species Aeromonas hydrophila.