This study shows that the disease resistance and survival
rate of Penaeus monodon in a larval rearing systems
can be enhanced by supplementing with antagonistic
or non-antagonistic probiotics. The antagonistic mode
of action of Pseudomonas MCCB 102 and MCCB 103
against vibrios was demonstrated in larval mesocosm
with cultures having su⁄cient concentration of antagonistic
compounds in their culture supernatant. Investigations
on the antagonistic properties of Bacillus
MCCB 101, Pseudomonas MCCB 102 and MCCB 103
and Arthrobacter MCCB 104 against Vibrio harveyi
MCCB111under in vitro conditions revealed that Pseudomonas
MCCB 102 and MCCB 103 were inhibitory to
the pathogen.These inhibitory propertieswere further
con¢rmed in the larval rearing systems of P. monodon.
All these four probionts signi¢cantly improved larval
survival in long-term treatments as well as when challengedwith
a pathogenic strain ofV. harveyiMCCB111.
We could demonstrate that Pseudomonas MCCB 102
andMCCB103 accorded disease resistance and a higher
survival rate in P. monodon larval rearing systems
throughactive antagonism of vibrios,whereas Bacillus
MCCB 101 and Arthrobacter MCCB 104 functioned as
probiotics through immunostimulatory and digestive
enzyme-supporting modes of action.