Isolation and characterization of Vibrio alginolyticus isolated from diseased kuruma prawn, Penaeus japonicus

Outbreaks of serious mortality among cultured kuruma prawns (Penaeus japonicus) with white spotted syndrome in the carapace occurred in the summer of 1993 in I-Lan, Taiwan. A swarming bacterium, strain Swy, was isolated from the hepatopancreas of the moribund prawns using tryptic soy agar supplemented with 1% NaCl and/or thiosulphate citrate bile salt sucrose agar. This strain was characterized and identified as Vibrio alginolyticus on the basis of a number of biochemical tests. The Swy strain was virulent to both kuruma prawns (P. japonicus) and tiger prawns (P. monodon) with LD50 values of 4.43 x 10(4) and 1.57 x 10(5) cfu g body weight-1, respectively.