Cảm nhiễm tôm Hùm bông (Panulirus ornatus) giai đoạn con non với vi khuẩn Vibrio owensii DY05

Several bacterial species of Vibrio genus are usually pathogens to marine cultured animals. Vibrio owensii strain DY05 has just recently been demonstrated as an agent of disease causing rapid  and  high  mortality  in  phyllosoma  larva  of  ornate  spiny  lobster  (Panulirus  ornatus) cultured in Australia. This study aims to determine the infection effect of V. owensii DY05 on the  mortality  rate  of  spiny  lobster  juveniles  cultured  at  the  lab  scale  in  Vietnam.  Loster juveniles were cultured in 6 tanks with 10 individuals (12-15 g each) per tank. Lobsters were exposed to DY05 at 10 3, 10 4, 10 5 , 10 6  and 10 7  CFU.ml-1 dosages (Tank A, B, C, D, and E, respectively) using direct immersion. Tank F without bacterial infection was used as control. After 20 infection days, mortality rates in tanks A, B, C, D, E and F were 0, 20, 25, 55, 85 and 0 (%), respectively. Specific death signs were observed including no eating 2 - 3 days before the dealth, slow movement, red tail and abdomen. V. owensii DY05 was virulent to lobster juvenile at LD 50  10 5.833 CFU.ml -1. The cell counts of total Vibrio reisolated from dead lobsters were 3.5x10 3 to 7.1x10 3  (CFU.g -1 ). Histopathological examination on dead lobsters showed necrotic  hepatopancreas tubules and broken thoracic musculature bond. The results suggest that V. owensii DY05 may be a pathogen in ornate spiny lobster juvenile in the condition of this study. This is the first report on experimental infection of V. owensii DY05 on postlarval spiny lobsters.