AN ANALYSIS OF THE ROLE OF SILVER NANOPARTICLES AS AN ANTIMICROBIAL AND IMMUNOSTIMULANT AGENT IN AQUACULTURE
Mariela Cisco, School of Veterinary Medicine, University of Pennsylvania
Mariela Cisco, Yang Ding, Yasuhiro Shibasaki, J. Oriol Sunyer
Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, 19014
Heavy use of antibiotics in aquaculture and the development of antibiotic resistance are the growing problems for food security and global health. Silver nanoparticles (Ag-NPs) have attracted immense attention as an alternative approach to control infectious agents. The aim of this study was to evaluate the inhibitory effects of Ag-NPs against distinctive fish pathogens, including one of the most detrimental parasites, Ichthyophthirius multifiliis (Ich), and two bacteria, Flavobacterium columnare (F. columnare) and Yersinia rukeri (Y. rukeri). These pathogens were exposed to Ag-NPs (particle size < 100 nm) at final concentrations of 0 (control), 1, 2, 10, 50, 100, and 250 μg/mL. Ag-NPs demonstrated significant inhibitory effects on Ich tomonts at 2 hours post cohabitation, as 63% to 87% of tomonts were killed by Ag-NPs of 1 to 100 μg/mL, compared to the 29% mortality rate observed in controls. Ag-NPs of 50 and 100 μg/mL could result in ~100% mortality of tomonts at 4 hours. ~100% mortality of the infective theronts was also observed after 4 hours post cohabitation with different concentrations of Ag-NPs. The antibacterial activity of Ag-NPs was also tested against F. columnare and Y. rukeri. Ag-NPs significantly inhibited the growth of F. columnare and Y. rukeri at concentrations of 100 and 250 μg/mL 24 hours post inoculation, respectively. We are currently evaluating the potential immunostimulatory action of Ag-NPs on rainbow trout immunity with the use of a panel of recently developed antibodies to trout immune cells and molecules, some of which were developed by the Immune Reagent Network for Aquacultured Species, funded by the US Department of Agriculture. Overall, our findings reveal strong antimicrobial properties of silver nanoparticles against the ectoparasitic Ich, as well as prevalent fish bacterial pathogens. In conclusion, we demonstrated that silver nanoparticles have significant promise in the aquaculture industry, opening new avenues of antimicrobial exploration for imminent cures and strategies. Future studies will allow the initial discovery to be confirmed and propelled.