The immensity of using antibiotics in aquaculture has many drawbacks on the industry itself and on consumers' health. The alternatives of using antibiotics are usually questionable. The current study was trying to find out the effect of Nanosilver (AgNPs) on some bacterial pathogens infecting Oreochromis niloticus (O.niloticus) in Egypt. The antibacterial activity of the AgNPs was assessed by well diffusion method. Different concentrations of the AgNPs were analyzed by MIC and MBC techniques. Finally the potential AgNPs which showed maximum antibacterial activity was also subjected for the time kill assay method. The in vitro study revealed that the AgNPs suspension at concentration of 50 ppm showed maximum activity against Aeromonas hydrophila, Pseudomonas aeruginosa and streptococcus agalactiae. It is also noted that, 50 ppm concentrations of the AgNPs showed the maximum reduction of bacterial growth, inhibit the bacterial motility, reduced the pigment production by P. aeruginosa, with highest inhibition zone on MH agar against the 3 bacterial species. Moreover, the effects of AgNPs on the 3 bacteria detected under TEM and the results were tremendous efficacy. It is concluded from the present study, AgNPs could be used as an effective antibacterial agents for disease free fish management.
Key words: Bacteria, O.niloticus, nanosilver, Antibiotics
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