Isolation and characterization of Vibrio alginolyticus from cultured amphioxus Branchiostoma belcheri tsingtauense

Amphioxus is an intermediary species bridging invertebrates and vertebrates used to study the development and evolution of species and genes. In this study, the dominant bacterial strain was isolated from tail lesions of cultured amphioxus and designated WW1. Challenge by intramuscular microinjection revealed the 50% lethal dose of WW1 to be 9 × 10 2 bacteria/g amphioxus body weight. Based on 16S rRNA gene sequence, physiological and biochemical characteristics, and species-specific collagenase gene marker, WW1 was identified as Vibrio alginolyticus . To our knowledge, this is the first report on the isolation of V. alginolyticus as pathogen from amphioxus. This study extends the known host range of V. alginolyticus and may provide information helpful in preventing and managing its occurrence in cultured animals.