Vibrio tarriae sp. nov., a novel member of the Cholerae clade

Abstract

A number of bacteria with close resemblance to <i>Vibrio cholerae</i> have been isolated over the years by the Centres for Disease Control and Prevention (CDC), which could not be assigned a proper taxonomic designation on the basis of the results from preliminary identification methods. Nine such isolates have been found to share 16S rRNA gene identity exceeding 99 % with <i>V. cholerae,</i> yet DNA-DNA hybridization (60.4-62.1 %) and average nucleotide identity values (94.4-95.1 %) were below the species cut-off, indicating a potentially novel species. Phylogenetic analysis of core genomes places this group of isolates in a monophyletic clade, within the 'Cholerae clade', but distinct from any other species. Extensive phenotypic characterization reveals unique biochemical properties that distinguish this novel species from <i>V. cholerae</i>. Comparative genomic analysis reveals a unique set of siderophore genes, indicating that iron acquisition strategies could be vital for the divergence of the novel species from a common ancestor with <i>V. cholerae</i>. On the basis of the genetic, phylogenetic and phenotypic differences observed, we propose that these isolates represent a novel species of the genus <i>Vibrio</i>, for which the name <i>Vibrio tarriae</i> sp. nov. is proposed. Strain 2521-89 ^T (= DSM 112461=CCUG 75318), isolated from lake water, is the type strain.