Toxicity of extracellular products of Vibrio anguillarum.

Vibrio anguillarum produced heat labile(70°C, 10 min) exotoxin lethal to goldfish, Japanese eel, ayu and mouse when injected. The extracellular products(ECP)from cellophane plate cultures(nutrient agar or BHI agar)at 20°Cor 25°Cfor 18-36 h were toxic, but not in 24 h BHI broth culture at 25°C. No lethal endotoxin was detected in filtrate of sonicated cells or heated cells obtained from cellophane plate culture.The lethal dose of the crude ECP from a high virulent strain was approximately 15μg protein/g fish(goldfish).Proteolytic activity of ECP, which was measured by using azocasein as reaction substrate, was re-cognized to coexist together with lethal toxicity. When virulent strains were compared with low virulent strains, the production of the lethal exotoxin and protease well correlated with the virulence.