Silver nanoparticles against acute hepatopancreatic necrosis disease (AHPND) in shrimp and their depuration kinetics

Abstract

Ag-based nanoparticles (NPs) were successfully produced through green synthesis using an aqueous extract from the cultivated seaweed Ulva clathrata as the reducing and stabilizing agent. The biosynthesized NPs had spherical to polymorphic shapes with an average size of 9.5 nm. Microstructural and compositional studies revealed that these particles contained face-centred cubic crystallites of metallic Ag and AgCl. Characteristic peaks in the Fourier-transform infrared spectrum (FTIR) and Raman studies revealed the presence of functional bioactive metabolites from the seaweed extract, such as proteins, polysaccharides, and polyphenols, which are responsible for forming and stabilizing Ag/AgCl NPs. The biosynthesized Ag/AgCl NPs exhibited an important in vitro antibacterial effect against three Vibrio parahaemolyticus strains isolated from farmed shrimp affected with acute hepatopancreatic necrosis disease (AHPND) in northwestern Mexico. Litopenaeus vannamei shrimp were exposed for 7 days to feeds supplemented with Ag/AgCl NPs at 10, 100, 1000, or 10,000 ppm (Ag nominal dietary concentrations). Dietary NP supplement did not affect shrimp survival, growth, or feed conversion ratio, but high concentrations (1000 and 10,000 ppm) decreased the hepatosomatic index significantly. The short-term consumption of Ag/AgCl NPs produced a significant dose-dependent bioaccumulation of Ag in the hepatopancreas and to a lesser extent in the cuticle, while bioaccumulation in the muscle was not significant. The depuration study confirmed a fast Ag assimilation in shrimp’s hepatopancreas and showed a fast depuration rate in the hepatopancreas as well.