Antimicrobial efficiency against fish pathogens on the green synthesized silver nanoparticles

Area of Science:

• Nanotechnology in Aquaculture
• Green Synthesis of Nanomaterials
• Antimicrobial Agents

Background:

• Aquaculture faces challenges with antibiotic-resistant fish pathogens, including Aeromonas hydrophila and Flavobacterium aquidurense.
• Conventional methods for pathogen removal are often insufficient or rely on antibiotics, leading to resistance issues.

Purpose of the Study:

• To synthesize silver nanoparticles (AgNPs) using a green chemistry approach.
• To evaluate the antimicrobial and antioxidant efficacy of synthesized AgNPs against fish-borne pathogens.
• To explore AgNPs as a sustainable alternative to antibiotics in aquaculture.

Main Methods:

• Green synthesis of AgNPs using Azadirachta Indica leaf extract and silver nitrate.
• Characterization of AgNPs using XRD, UV-Vis spectroscopy, EDX, FT-IR, SEM, and TEM.
• Assessment of antioxidant activity via DPPH assay and antimicrobial efficacy using the agar diffusion method.

Main Results:

• Synthesized AgNPs exhibited a face-centered cubic structure with SPR peaks at 440 nm and an optical band gap of 2.81 eV.
• TEM and DLS confirmed spherical AgNPs with sizes around 40-62 nm, and a zeta potential of -12 mV indicated stability.
• AgNPs displayed significant free radical scavenging activity (84% at 100 μg/mL) and potent antimicrobial effects against A. hydrophila (28 mm zone) and F. aquidurense (25 mm zone).

Conclusions:

• Green synthesized AgNPs possess strong antioxidant and antimicrobial properties, validated by DPPH and antimicrobial assays.
• These AgNPs represent a promising, antibiotic-free alternative for managing fish-borne pathogens in aquaculture.
• Optimized concentrations of AgNPs showed no adverse effects on zebrafish and brine shrimp, supporting their safe application in fisheries.