Improved resistance to Vibrio parahaemolyticus in black tiger shrimp Penaeus monodon treated with Streptococcus phocae PI80 and Bacillus subtilis

The aim of the study was to establish the immune response induced by Streptococcus phocae PI80, Bacillus subtilis, and commercial probiotics (Uni-Ecosense, EcoForce, Uni-Hatch) in the shrimp, Penaeus monodon. Total hemocyte count, phenoloxidase activity, nitroblue tetrazolium (NBT) reductase assay, phagocytic activity, and disease resistance was evaluated for 30 days. Total hemocyte count, phenoloxidase activity, NBT reductase assay, and phagocytic activity significantly increased in juveniles and adults treated with S. phocae PI80, a mixture of S. phocae PI80 and B. subtilis, or a commercial probiotic, but there were no significant differences in live weight of shrimps treated with probiotics or the control. Treatment with S. phocae PI80 plus B. subtilis enhanced survival of shrimps challenged with Vibrio parahaemolyticus. Our study demonstrates that administration of S. phocae PI80+B. subtilis at 4.6 × 10⁸ CFU/ml water induced immune modulation, enhanced immune ability, and increased resistance to V. parahaemolyticus in juvenile and adult black tiger shrimp.