Some Vibrio species carry a plasmid called pVA1 that encodes the PirA and PirB toxins, causing acute hepatopancreatic necrosis disease (AHPND). Antibiotics have usually been used to counteract its development. However, many antibiotics are leached into the water, diminishing their concentration and promoting the emergence of resistant strains. In the present study, we evaluated in-vitro, the antibacterial function of silver nanoparticles (AgNPs) against three Vibrio strains that are carrying the pVA1 plasmid: V. parahaemolyticus, V. harveyi and V. campbellii. The results showed that AgNPs inhibited the development of the three strains in liquid and solid cultured media.
The solid media was prepared on plates with trypticase soy agar (TSA) medium with NaCl 3%. The culture media were supplemented with AgNPs until concentration reached 100, 10, 1, 0.1, and 0 µg of AgNPs/ml of the medium before pouring into the plate. In another experiment, trypticasein soy liquid medium (TSB) was prepared with NaCl 3% and supplemented with 40, 30, 10, 5, and 0 µg of AgNPs/ml of medium. Vibrio strains were plated in TSA, inoculated in TSB, and incubated at 30 °C for 18 h. The results showed an apparent inhibition of the three strains in TSA (Figure 1 A, B, and C) and TSB (Figure 2 A, B, and C). These results will contribute to the discovery of new control strategies against AHPND in shrimp farms without the use of antibiotics.