Vibrio ponticus sp. nov., a Neighbour of V. fluvialis-V. furnissii Clade, Isolated from Gilthead Sea Bream, Mussels and Seawater M. C. Macián 1,2 , E. Garay 1,2,3 , P. A. D. Grimont 4 , and M. J. Pujalte 1,2 1 Instituto Cavanilles de Biodiversidad y Biología Evolutiva, Universitat de València, Spain 2 Departamento de Microbiología y Ecología, Universitat de València, Spain 3 CECT, Spanish Type Culture Collection, Universitat de València, Spain 4 Unité Biodiversité des Bactéries pathogènes émergentes, INSERM U389, Institut Pasteur, Paris, France Received: May 3, 2004 Summary A new Vibrio species, Vibrio ponticus, is proposed to accommodate four marine bacteria isolated from sea water, mussels and diseased sea bream (Sparus aurata), at the Mediterranean coast of Spain. Strains are Gram negative, slightly halophilic bacteria that require Na + ion for growth, oxidase and catalase pos- itive, negative for arginine dihydrolase and ornithine decarboxylase but positive for lysine decarboxylase and indole, and utilize β-hydroxybutyrate as a sole carbon source. Phylogenetic analysis locate these marine bacteria in the vicinity of the V. fluvialis-V. furnissii clade, sharing with these two species 16S rDNA sequence similarities slightly above 97% (97.1 and 97.3%, respectively). DNA-DNA hybridisation values confirm that the four strains form a genospecies and represent a new species in the genus Vibrio. We propose strain 369 T (CECT 5869 T , DSM 16217 T ) as the type strain. Key words: Vibrio ponticus sp. nov. – γ-Proteobacteria – sea water – mussels – diseased Sparus aurata – DNA-DNA hybridisation – 16S rDNA phylogeny Introduction The genus Vibrio accounts for near 60 validly de- scribed species, most of them of marine origin. Some Vib- rio species have been implicated in human and marine an- imal pathologies, as well as in symbiotic relationships with luminescent fish and cephalopods [6]. Vibrio anguil- larum, V. ordalii, V. salmonicida and V. vulnificus are among the most virulent fish pathogens, but several oth- ers have been linked to mortalities in cultured fish, some- times as opportunistic pathogens. Most of the recently described species come from the aquaculture environ- ment, being associated to food [8, 20], cultured fish or shellfish [13, 21, 22] and other marine invertebrates [3]. Strains sharing the common basic traits of genus Vib- rio, but not identified at species level, were isolated be- tween 1999 and 2001 from kidney of several healthy and diseased sea bream, Sparus aurata, cultured in different hatcheries at the Spanish Mediterranean coast [17]. These strains were labelled as Vibrio sp. LB+, meaning that they were positive for lysine decarboxylase and use of β-hy- droxybutyrate. The data did not allow the adscription to any of the currently described Vibrio species, but related them to a group of three unidentified vibrio strains isolat- ed by our group in the same geographical area during a previous study of bacteria associated with mussels and seawater [14, 15]. In this study we report on the taxonomic characterisa- tion of one strain from those isolated from sea bream [17] together with the three strains of phenon 25 origi- nated from mussels and seawater [14, 15]. We propose that these isolates of different origins represent a new Vibrio species i.e. V. ponticus. 0723-2020/04/27/05-535 $ 30.00/0 System. Appl. Microbiol. 27, 535–540 (2004) http://www.elsevier.de/syapm Nucleotide sequence data reported are available in the EMBL under the accession numbers: AJ630102, AJ630103, AJ630202 and AJ630203.