Probiotics and immunostimulants modulate gut microbiome and immune gene expression in post-larval Litopenaeus vannamei

Globally, shrimp production reaches approximately five million metric tons annually to satisfy growing demand. However, suboptimal culture conditions have rendered shrimp increasingly susceptible to diverse diseases, making disease prevention and immune enhancement essential. Probiotics and immunostimulants have emerged as key strategies to strengthen shrimp immunity, with probiotics supporting a balanced gut microbiome and immunostimulants modulating the host immune response. This study evaluated the effect that varying doses of probiotics and immunostimulants can have on immune-related genes as well as the gut health in the post-larvae (PL) white leg shrimp. Over 38 days, the Post Larvae (PL) were provided with either of three dietary regimes: a particle/basal diet (control group), immunostimulant or probiotics. Gut microbiota composition and the expression of target immune genes responsible for the host's immunity were assessed. Immunostimulants given at the rate of 1 ppm enhanced the expression of Anti-lipopolysaccharide gene as compared to control group. Probiotics at all dosage (0.5, 1 and 2 ppm) enhanced Prophenoloxidase (proPO) expression, while Immunostimulants given at 0.5 and 1 ppm enhanced the expression of proPO in PL shrimp. The gut microbiome diversity was higher in control group as compared to both Probiotics and Immunostimulants group. But the abundance of specific bacteria family like Proteobacteria was higher in probiotics which might be due to Probiotics favoring the growth of certain bacteria family.