Phylogeny of the Vibrionaceae, and Recommendation for Two New Genera, Listonella and Shewanella

Ribonucleotide sequences were determined for 5S rRNAs purified from 31 type cultures and freshly isolated strains representing species of the eubacterial family Vibrionaceae. These were compared with published 5S rRNA sequences for 11 other species of rRNA superfamily I (Vibrionaceae, Enterobacteriaceae) for the purpose of constructing a phylogenetic taxonomy of the Vibrionaceae. Sequence data were compiled and analyzed, using single, average, and complete linkage clustering methods, resulting in the generation of evolutionary trees. Results of this study indicate a good correlation between the taxonomy of the Vibrionaceae established using conventional and molecular genetic data and evolutionary relationships deduced from 5S rRNA sequences. However, several species, including V. anguillarum, V. pelagius, V. damsela, V. fischeri, V. logei, V. psychroerythrus, V. marinus, and Plesiomonas shigelloides require reconsideration of their taxonomic status, based on the new information obtained in this study. Furthermore, the genus Aeromonas appears to be sufficiently distantly related to the Vibrionaceae to warrant exclusion from the family Vibrionaceae. We propose a restructuring of the family Vibrionaceae along phylogenetic lines, and establishment of two new genera Listonella and Shewanella, and a new family Aeromonadaceae.