Adherence and pathogenicity assay of vibrio liarveyi in tiger shrimp (Penaeus monodon) larvae for Screening Biocontrol Agent

Abstract

Rifampicin-resistant marker was employed as a reporter to detect the adherence and colonization of V . 1trtrvc)~i n shrimp larvac. Vibrio harveyi PlB and YA32.2 were isolated from dead shrimp larvae in Besuki, Northern Coast of East Java, while V. hurveyi HB3, was isolated from pristine sea water in Pacitan, Southern Coast of East Java. Vibrio me~schnitoviiu sed as biocontrol agent was isolated from healthy shrimp larvae in Serang, West Java. Spontaneous mutation was conducted to generate V. hurvcyi P1B. YA32.2 and HB3 resistant to rifampicin. These mutants exhibited similar survival ability to their parental (wild typc) strains. Significant larval mortality was observed in shrimp larvae inoculated with YA32.2 than that of larvae inoculated with PIB. Larvae inoculated with HB3 showed thc lowest mortality. Bacterial cell count of Vibrio RP in dead larvae were lo3-10' cellsliarvae. kolates of Vibrio mefschnikovii Z and M as biocontrol candidates effectively reduced the growth and adherence ability of YA32.2 to shrimp larvae. Larval mortality in rearing water inocvlated simultaneously with YA32.2 and V. ntefschnikovii was lower than the one inoculated with YA32.2 alone. Therefore. Vibrio mefschnikovii Z or M could be developed as an effective probiotic or biocontrol agent for V. hrveyi in shrimp hatcheries. Key words : Biolc~gicalc ontro~lVil~rtiiote tscltnikuviilsl~ri~Ita~rpv adlJcnucus nu~n~~~/or~lpu~l~t,gct~ic.icy assaylVibric~h urveyi