Low dose of Nodulisporium sp. KT29 metabolite promotes production performance and innate immunity of Pacific white leg shrimp (Litopenaeus vannamei) against co-infection of white spot syndrome virus and Vibrio harveyi

This study aimed to determine the effective dose of Nodulisporium sp. KT29 metabolite for enhancing the production and innate immunity of Pacific white leg shrimp (Litopenaeus vannamei) against co-infection of white spot syndrome virus (WSSV) and Vibrio harveyi. Nodulisporium sp. KT29 isolate used in this study was a marine algicolous fungus isolated from Euchema edule. A field-scale experiment was conducted in floating net cages for 30 days using postlarvae 10 (0.0032 ± 0.01 g/shrimp) as experimental animals. This experiment tested three doses of Nodulisporium sp. KT29 metabolite including 0 (control), 10 (L10), and 20 mL/kg feed (L20) in triplicate. The metabolite was orally administered to the shrimp. A laboratory-scale experiment was conducted in controlled tanks with co-infection of WSSV and V. harveyi for 10 days, consisting of four treatments of Nodulisporium sp. KT29 metabolite including 0 (C + : positive control and C-: negative control), L10, and L20 in triplicate. The observation parameters in the challenge test included survival and immunological parameters consisting of phenoloxidase activity (PO) and respiratory burst (RB). The shrimp fed with fungal metabolite showed better results in zootechnical parameters than those of control. Innate immunity of shrimp was positively affected by Nodulisporium sp. KT29 metabolite, demonstrated by the higher pre-challenge test and post-challenge test PO and RB of treated groups than those of C + and C-. Conclusively, a low dose of Nodulisporium sp. KT29 metabolite could enhance the production and innate immunity of Pacific white leg shrimp against the co-infection of WSSV and V. harveyi.