title: Phylogenetic study and identification of Vibrio splendidus-related strains based on gyrB gene sequences.
abstract: Different strains related to Vibrio splendidus have been associated with infection of aquatic animals. An epidemiological study of V. splendidus strains associated with Crassostrea gigas mortalities demonstrated genetic diversity within this group and suggested its polyphyletic nature. Recently 4 species, V. lentus, V. chagasii, V. pomeroyi and V. kanaloae, phenotypically related to V. splendidus, have been described, although biochemical methods do not clearly discriminate species within this group. Here, we propose a polyphasic approach to investigate their taxonomic relationships. Phylogenetic analysis of V. splendidus-related strains was carried out using the nucleotide sequences of 16S ribosomal DNA (16S rDNA) and gyrase B subunit (gyrB) genes. Species delineation based on 16S rDNA-sequencing is limited because of divergence between cistrons, roughly equivalent to divergence between strains. Despite a high level of sequence similarity, strains were separated into 2 clades. In the phylogenetic tree constructed on the basis of gyrB gene sequences, strains were separated into 5 independent clusters containing V. splendidus, V. lentus, V. chagasii-type strains and a putative new genomic species. This phylogenetic grouping was almost congruent with that based on DNA-DNA hybridisation analysis. V. pomeroyi, V. kanaloae and V. tasmaniensis-type strains clustered together in a fifth clade. The gyrB gene-sequencing approach is discussed as an alternative for investigating the taxonomy of Vibrio species.
authors.affiliation: Laboratoire de Génétique et Pathologie, Institut français de recherche pour l'exploitation de la mer, 17390 La Tremblade, France. fleroux@ifremer.fr
authors.forename: Fredérique
authors.initials: F
authors.lastname: Le Roux
authors.forename: Mélanie
authors.initials: M
authors.lastname: Gay
authors.forename: Christophe
authors.initials: C
authors.lastname: Lambert
authors.forename: Jean Louis
authors.initials: JL
authors.lastname: Nicolas
authors.forename: Manolo
authors.initials: M
authors.lastname: Gouy
authors.forename: Franck
authors.initials: F
authors.lastname: Berthe
mesh_terms: D000818:Animals; D001483:Base Sequence; D016000:Cluster Analysis; D004247:DNA / Q000378:metabolism; D027081:DNA Gyrase / Q000235:genetics*; D004275:DNA, Ribosomal / Q000235:genetics; D014644:Genetic Variation; D008969:Molecular Sequence Data; D010125:Ostreidae / Q000382:microbiology*; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D014733:Vibrio / Q000235:genetics*
chemical_list: D004275:DNA, Ribosomal; D004247:DNA; D027081:DNA Gyrase