Characteristics and Pathogenicity of Brown Pigment-Producing Vibrio anguillarum Isolated from Japanese Flounder

Abstract

A Gram-negative rod-shaped bacterium was isolated from diseased Japanese flounder Paralichthys olivaceus (mean total length, 33 mm), during a disease outbreak in a flounder hatchery in Fukui Prefecture, Japan in 2005. The isolated bacterium produced water-soluble brown pigment and was identified as Vibrio anguillarum serotype A (J-O-1) by biochemical and serological tests, and 16S rDNA sequence. The pathogenicity of the isolated bacterium to Japanese flounder was confirmed by intraperitoneal injection, but not by bath immersion. This is the first report of isolation of brown pigment-producing V. anguillarum.