Efficacy of marine yeasts and baker's yeast as immunostimulants in Fenneropenaeus indicus: A comparative study

Efficacy of marine yeasts Debaryomyces hansenii (S8) and Candida tropicalis (S186) as immunostimulants to Indian white prawn Fenneropenaeus indicus was estimated in comparison with Saccharomyces cerevisiae S36. Biomass of yeast strains was prepared using Malt Extract Agar and incorporated into a standard diet to prepare yeast diets of varying concentrations. F. indicus were fed these diets for a period of 14 days and then challenged orally with white spot syndrome virus (WSSV) and immune assays like total hemocyte count, phenol oxidase, NBT reduction, alkaline phosphatase and acid phosphatase were performed. Generally yeast diets provided better protection to F. indicus against WSSV compared to control. Marine yeast diet was found to support maximum immunostimulation evidenced by enhanced shrimp immunity. The study showed that marine yeasts D. hansenii (S8) and C. tropicalis (S186) are effective immunostimulants in F. indicus and they perform better than the baker's yeast, S. cerevisiae.

► Marine yeasts enhance the immunity by stimulating the non-specific immune system.
► Enhanced immunity causes delayed and lesser mortality in prawns.
► As marine yeasts are halotolerant it can be used in brackish/seawater aquaculture.
► Halotolerance of marine yeasts prevents cell burst and water quality deterioration.