Immune response and resistance against Vibrio parahaemolyticus in whiteleg shrimp (Litopenaeus vannamei) by dietary supplementation of a Saccharomyces cerevisiae fermentation-derived postbiotic (SCFP)

Abstract

Postbiotics are used in animal husbandry as dietary supplements that function as immunostimulants by activating blood cell signaling pathways, thereby inducing a heightened immune response and contributing to host protection. In this study, we evaluated the effects of a Saccharomyces cerevisiae fermentation-derived postbiotic (SCFP) on the survival rate, histopathological features, and immune responses of whiteleg shrimp (Litopenaeus vannamei) following challenge with Vibrio parahaemolyticus strain CED12.020. The experiment was conducted using three different treatment groups: (S3) shrimp fed a diet supplemented with 0.45 % SCFP for 45 days, followed by bacterial challenge; (PC) shrimp fed a non-supplemented diet for 45 days, followed by bacterial challenge; and (NC) shrimp fed a non-supplemented diet without bacterial challenge. The results demonstrated that immune parameters, including hemocyte count (THC), granulocyte count (GC), hyalinocyte count (HC), phenoloxidase activity (PO), respiratory burst activity (RES), and superoxide dismutase activity (SOD), were significantly higher in the S3 group compared to the PC and NC groups at all time points (0 h, 12 h, 24 h, 48 h, 96 h, 7 days, and 14 days) following challenge with V. parahaemolyticus (p < 0.05). The immune response of shrimp declined after 12 h, reaching the lowest point at 48 h post-infection, after which it gradually recovered and increased. The survival rate of shrimp in the S3 group after 15 days of bacterial challenge was significantly higher (82.15 %) compared to the PC group (45.94 %) (p < 0.05). These findings provide strong evidence that dietary supplementation with 0.45 % SCFP enhances the immune response and disease resistance of whiteleg shrimp against the pathogenic bacterium V. parahaemolyticus.