ADHERENCE AND PA THOGENICITY ASSA Y OF VIBRIO HARVE YI IN TIGER SHRIMP (PENAEUS MONODON ) LARVAE FOR SC REENING BIOCONTROL AGE NT

Rifampicin-resistant marker w as empl oyed as a repor ter t o detect the ad here nce and colonization of V. harve yi in s hrimp larvae. Vibri o h arve yi P1B and YA3 2. 2 were isolated f rom dead s hrimp la rv ae i n Besuki, Norther n C oast of East Jav a, while V. harveyi HB3, was isolated from pris tine sea water in Pacita n, S outhe rn Coast of E ast Ja va . Vi brio metsc hnikovii used a s bioc ontr ol a gent was i solated fr om healthy shrimp larvae in Serang, We st Java. Spontane ous mutation was c onducted to generate V. harveyi P1B, YA32.2 and HB3 resistant to rifampi cin. These mutants exhibit ed similar survival ability to t heir parent al (wild type) strai ns. Signifi cant larval mortalit y was o bserv ed i n s hrimp l arv ae i noculated with YA32.2 than that of larvae ino culated with P1B. Larvae inoculated with H B 3 showed the lo w est mortality. Bacterial cell c ount of Vi brio Rf* in dead larvae w ere 103-104 cells/larvae. Isolates of Vi brio metschnikovii Z an d M as biocontrol candid ates effectively r educed the growth a nd a dherence ability of YA32.2 t o shrimp larvae. Larval mort ality in rearing water inoculat ed simultaneousl y w ith YA32.2 and V. metschnikovii was lower than the one inoculated with YA32.2 alone. Therefore, Vibrio metschnikovii Z or M could be develope d as an effective pro biotic or biocontrol agent for V. harvey i in shrimp hatcheri es.