Assessment of antibacterial activity of two different sizes of colloidal silver nanoparticle (cAgNPs) against Vibrio harveyi isolated from shrimp Litopenaeus vannamei

Silver nanoparticles are the most important nanomaterials for antibacterial uses and are famous for their strong inhibitory and antibacterial effects. In recent years, extensive studies have been undertaken on the use of antimicrobial properties of silver, incorporated within aquaculture industry. To evaluate the scientific basis for the use of the nano silver in shrimp aquaculture, in this study the antimicrobial activities of colloidal nano silver with two different sizes (16.62 and 22.22 nm) was evaluated against gram negative bacteria, V. harveyi. Before the experiments, cAgNPs were characterized using several analytical techniques. Well diffusion method, micro-dilution tests (MIC and MBC) and kinetic of death were used to evaluate the bactericidal activity of the nanoparticles. Results showed that MIC and MBC values of cAgNPs in both studied sizes are equal (MIC = MBC). Best bactericidal kinetics in the presence of 16.62 and 22.22 nm nanoparticles obtained at 4 and 6 h, respectively. The obtained results suggested that smaller silver nanoparticles had a faster antibacterial activity than the larger particles. According to the obtained results, the activity of cAgNPs against V. harveyi is fast and has potential for the treatment of bacterial infection in aquaculture.