Response of Macrobrachium rosenbergii juvenile against a virulent isolate of Vibrio sp. from a diseased Penaeus monodon

Abstract

The present study investigated the in vivo virulence of a Vibrio sp. isolated from a diseased tiger shrimp (Penaeus monodon) and determined the median lethal concentration (LC₅₀) of Vibrio sp. against giant prawn (Macrobrachium rosenbergii) juveniles at the cell densities of 10⁴, 10⁵, 10⁶, 10⁷ CFU/mL. In addition, the survival rate of M. rosenbergii was examined through a bath challenge test against the Vibrio sp. isolate at different cell densities. The results showed that the median LC₅₀ of Vibrio sp. for M. rosenbergii was 10⁶ CFU/mL by probit-transformed responses. Vibrio sp. concentrations had no effect on the mortality of prawn juveniles; however, infection time might significantly increase the mortality (p = 0.000). Lower survival of prawn juveniles was also recorded at the bacterial cell density of 10⁶ CFU/mL. Finally, Vibrio sp. cell density 10⁴ CFU/mL showed lower cumulative percent survival and higher hazard function compared to other concentrations. This study provides an indication that pathogenic Vibrios of tiger shrimp can be a potential risk for M. rosenbergii larvae culture. Further studies should be conducted to unravel the mechanism of actual mortality factor, possibly quorum sensing regulatory activities of the Vibrio sp. isolate.