Molecular and phenotypic characterization of Vibrio aestuarianus subsp. francensis subsp. nov., a pathogen of the oyster Crassostrea gigas

• Published in: Systematic and applied microbiology 2008-10, Vol.31 (5), p.358-365
• Main Authors: Garnier, Matthieu, Labreuche, Yannick, Nicolas, Jean-Louis
• Format: Article
• Language: English
• Subjects: animal pathogenic bacteria; Animals; Bacterial Typing Techniques - methods; Bacteriology; Biological and medical sciences; Crassostrea - microbiology; Crassostrea gigas; DNA, Bacterial - analysis; DNA, Bacterial - genetics; France; French isolates; Fundamental and applied biological sciences. Psychology; Genotype; Hemolymph - microbiology; Marine; Microbiology; molecular systematics; new geographic records; new species; Nucleic Acid Hybridization; oysters; Pathogen; Phenotype; phenotypic variation; Phylogeny; Polyphasic approach; RNA, Ribosomal, 16S - genetics; Species Specificity; Summer mortalities; Systematics; Vibrio; Vibrio - classification; Vibrio - genetics; Vibrio - isolation & purification; Vibrio - pathogenicity; Vibrio aestuarianus; Vibrio aestuarianus subsp. francensis; Virulence
• ISSN: 0723-2020; 1618-0984
• DOI: 10.1016/j.syapm.2008.06.003

Eleven Vibrio isolates invading the hemolymph of live and moribund oysters ( Crassostrea gigas) collected in the field and from a hatchery in France, were characterized by a polyphasic approach. Phylogenetic analysis of 16S rRNA, gyrB and toxR genes indicated high homogeneity between these strains and the Vibrio aestuarianus type strain (ATCC35048 T), and confirmed previous 16S rRNA analysis. In contrast, DNA:DNA hybridization was from 61% to 100%, while phenotypic characters and virulence tests showed a large diversity between the strains. Nevertheless, several common characters allowed the isolates to be distinguished from the reference strain. On the basis of several distinct phenotypic characteristics, it is proposed to establish two subspecies within the V. aestuarianus spp. group, V. aestuarianus subsp. aestuarianus [D. Tison, R. Seidler, Vibrio aestuarianus: a new species from estuarine waters and shellfish, Int. J. Syst. Bacteriol. (1983) 699–702] and V. aestuarianus subsp. francensis for these French isolates. The characters that differentiate the new strains from V. aestuarianus subsp. aestuarianus T are virulence (positive for 63% of the isolates) and 12:0 fatty acid content. The colonies were smaller and uncoloured, whereas no growth occurred at 35 °C or on TCBS, and the strains did not utilize several substrates, including l-serine, α-cyclodextrin, d-mannitol, α-glycyl- l-aspartic acid, l-threonine and glucose-1-phosphate.