DIETARY SUPPLEMENTATION OF Debaryomyces hansenii ENHANCED SURVIVAL, ANTIOXIDANT AND IMMUNE RESPONSE IN JUVENILE SHRIMP Penaeus vannamei CHALLENGED WITH Vibrio Parahaemolyticus

Background: The excessive use of antibiotics in shrimp aquaculture cause severe ecological damage.  Immunostimulant probiotics are an alternative prophylactic treatment to enhanceantioxidant and immune response to reduce mortality induced by pathogenic microbes. Objective: This study investigated the effect of live yeast Debaryomyces hansenii incorporated in diet and in culture water on survival and expression of the antioxidant and immune-related genes in Penaeus vannamei juvenile shrimp. Methodology: Shrimp were fed daily for 10 days with treatments of different doses and a post-infection with Vibrio parahaemolyticus as follows: a) control (-) without feed additives and non-infected; b) control (+) without feed additives and infected; c) D. hansenii, 1×106 CFU g-1 feed; d) inulin, 2.5 mg g-1 feed; e) D. hansenii, 1×106 CFU g-1 feed + inulin, 2.5 mg g-1 feed; f) D. hansenii, 2×106 CFU g-1 feed + 1×106 CFU mL-1; g) D. hansenii, 4×106 CFU g-1 feed + 1×106 CFU mL-1. Relative gene expression of lysozyme (LYS), glutathione peroxidase (GPX), and superoxide dismutase (SOD) were determined in shrimp muscle and hepatopancreas previous to challenge with V. parahaemolyticus. Results: Juvenile shrimp increased the resistance to V. parahaemolyticus infections significantly more than untreated shrimp after D. hansenii administration in feed and water, and mixed with inulin. Relative gene expressions of LYS and SOD increased significantly in shrimp muscle after treated with D. hansenii and D. hansenii + inulin, respectively. SOD and GPX were significantly expressed in shrimp hepatopancreas. Implications: The findings provide new insights to apply yeast immunostimulants in reared shrimp to increase immune response and survival against experimental bacterial infections. Conclusions: In this study, juvenile shrimp exposed to additive immunostimulants increased gene expression in shrimp tissues, muscle and hepatopancreas, and the dose of 1×106 CFU g-1 of D. hansenii in feed was sufficient to increase shrimp survival against V. parahaemolyticus infection.