Pathogenic bacteria from shellfish larvae: Vibrio neptunius, a newoyster pathogen

摘要

Shellfish hatcheries frequently suffer disease outbreaks caused by bacteria. During the past years, we had the opportunity to investigate episodes of mortalities in different Galician hatcheries. A number of bacterial isolates was obtained from the distinct compartments of each hatchery. Experimental tests were carried out to assess the virulence of the selected bacterial isolates using a microscale procedure in cell culture plates and healthy larvae of Ostrea edulis. Pathogenicity of one strain from each outbreak was demonstrated, causing high mortalities (ranging from 98.5 to 100%) in 72-96 h after inoculation. The three pathogenic strains belong to genus Vibrio. One of them, PP-145.98, can be assigned to Vibrio neptunius by sequencing of 16S rRNA gene, this being the first description of this species as mollusc pathogen. The other two pathogens, PP-203 and PP-638, showed biochemical and physiological differences from the Vibrio species analysed, and low similarities with their closest phylogenetic relatives (around 97%). These facts suggest that they may represent new species within this genus.