Pathogenicity and Characteristics of Vibrio sp. Isolated from Cultured Kuruma Prawn Penaeus japonicus BATE

Abstract

From August to November in 1982, an epizootic occurred among cultured kuruma prawn Penaeus japonicus BATE in Yamaguchi and Kumamoto Prefectures. The typical symptoms of the diseased kuruma prawn were cloudiness of muscle at the 6th abdominal segment, brown spot of gill and lymphoid organ. A bacterium was isolated from the heart, lymphoid organ and muscle of all the diseased kuruma prawn. By infectivity trials the bacterium was proved to be pathogenic to kuruma prawn. These organisms were gram-negative, non-sporning rods with a single polar flagellum, and usually 0.8 to 1.0 by 1.0 to 3.0μm in size. Growth on nutrient agar was observed at 10 to 30°C. Growth occurred in media with NaCl concentration of 1.0 to 3.0 or 4.0%, but no growth occurred in the medium with 5.0%. Growth occurred on BTB Teepol agar, but no growth occurred on SS agar, MacConkey agar or Aronson agar. The organisms gave positive oxidase and catalase reaction, utilized glucose fermentatively in Hugh-Leifson's medium and did not produce gas from carbohydrates. IMViC reactions were (+, + -, +). Some distinguishing features of the organisms were negative to lysine, arginine, ornithine decarboxilization test, arginine hydrolytic test, 2, 3-butandiol dehydrogenized test and swarming test, and utilization of lactate, gluconate, sorbitol and lactose. The organisms were sensitive to the vibriostatic agent 0/129 and novobiocin.
The above-mentioned properties suggest genus Vibrio, but these properties disagreed with those of known Vibrio. Therefore, under the present conditions that the organisms were not examined for DNA base composition, the isolates should be identified as Vibrio sp..