Isolation of a Vibrio sp., the causative bacterium of intestinal necrosis of Japanese flounder larvae

Abstract

In 1986-1988, a bacterial disease characterized by opaque intestine or intestinal necrosis with high mortality occurred in larval Japanese flounder (Paralichthys olivaceus) reared at private hatcheries and Prefectural Fisheries Experimental Station in Hiroshima Prefecture. From the intestine of the diseased larvae, a Vibrio species was isolated and tentatively named Vibrio sp. INFL (Intestinal necrosis of flounder larvae) group. The disease condition was reproduced by oral administration of the isolate incorporated into live food organisms : rotifer and brine shrimp. Based on the identical morphological and biochemical characteristics of the causative agent and the same disease symptom, this disease proved to be the same disease as the one reported previously in Wakayama Prefecture under the name of “Chohkanhakudakushoh” (disease with opaque intestine), although the serotype of the isolates was not identical.