Isolation, identification and pathogenicity characterization of Vibrio ponticus from the golden pompano Trachinotus ovatus

To determine the pathogeny for the mass death in the golden pompano Trachinotus ovatus in Hainan, China, the potential pathogens (HAINUV01, HAINUV02, and HAINUV03) were isolated from the infected pompano. The infected fish showed swollen, hyperemic livers and spleens, yellowish effusion in the gut, and different degrees of ulcerations on the bases of dorsal and pelvic fins. HAINUV01 had the strongest virulence to the pompano with a lethal dose (LD₅₀) of 14 days of 1.75 × 10² CFU/g fish by intraperitoneal (i.p.) injection. HAINUV01 was Gram-negative, straight rods, 2.37 ± 0.12 μm in length by 0.857 ± 0.003 μm width, with only one polar flagellum (4.78 ± 0.33 μm). Neighbor-joining phylogenetic analysis based on 16S rRNA, mreB, pyrH, recA and rpoA genes identified HAINUV01 as Vibrio ponticus. These findings provide direction for controlling V. ponticus-related disease occurrences in the future.