Immunophysiological Response of Pacific White Shrimp Exposed to a Probiotic Mixture of Proteobacteria and Firmicutes in Farm Conditions

The effect of a probiotic mixture (Proteobacteria-Firmicutes) on the immune and physiological responses of Pacific white shrimp Litopenaeus vannamei reared at commercial scale was evaluated. Shrimp were cultured into two different systems: a traditional system and a probiotic-based system using the probiotic mixture every day of culture. Hemolymph parameters and the expression of immune-related genes were monitored during the culture cycle. Shrimp reared in the probiotic-based system registered an upregulation of clotting protein (CP), prophenoloxidase (proPO), alpha-2-macrogolbulin (A2M), superoxide dismutase (SOD), and heat shock protein (hsp) 60 genes in hemocytes compared with those reared in the traditional system. Also, high transcription levels of CP, proPO, transglutaminase, beta glucan binding protein, SOD, hsp60, and hsp90 genes were detected in the hepatopancreatic tissue of shrimp reared with probiotics. While no significant differences were detected for hemolymphatic concentrations of glucose, lactate, and protein, lower concentrations of cholesterol and acylglycerides were detected in shrimp cultured with probiotics; in addition, we detected a higher activity of proPO and a lower activity of aminotransferases, and recorded better survival in these shrimp. Results suggest that the probiotic mixture we used had an immunostimulatory effect on the shrimp; the upregulation of all the genes studied suggests the activation of the complex immune network. From a physiological perspective, the results also indicate that probiotics can be effective at the commercial shrimp farm scale.