Antimicrobial Activity of Silver Nanoparticles Against Common Bovine Mastitis Pathogens: A Comparative Analysis

Area of Science:

• Nanotechnology
• Veterinary Medicine
• Microbiology

Background:

• Bovine mastitis, a significant metabolic disease in dairy cows, causes substantial economic losses globally, primarily due to infections by Staphylococcus aureus and Escherichia coli.
• Silver Nanoparticles (AgNPs) are recognized for their potent antimicrobial properties, making them a subject of interest for developing novel therapeutic agents.

Purpose of the Study:

• To synthesize and characterize Silver Nanoparticles (AgNPs) using both green and chemical methods.
• To evaluate the antimicrobial efficacy of synthesized AgNPs against Staphylococcus aureus and Escherichia coli.
• To compare the performance of green synthesized AgNPs with chemically synthesized AgNPs and commercial antibiotics.

Main Methods:

• Citrus limon extract was analyzed using Gas Chromatography-Mass Spectrometry (GC-MS) to identify abundant compounds like citric acid.
• AgNPs were synthesized via green (using citrus limon extract) and chemical routes.
• Characterization involved UV-Visible spectroscopy, electron microscopy, zeta sizing, and infrared spectroscopy.
• Antimicrobial activity was assessed by determining the Minimum Inhibitory Concentration (MIC) against S. aureus and E. coli.
• Cytotoxicity was evaluated using RAW264.7 cell viability assays.

Main Results:

• Both green and chemical AgNPs were successfully synthesized, exhibiting nanoscale dimensions (10-20 nm) and negative zeta potential.
• Green synthesized AgNPs demonstrated significantly higher antimicrobial activity (P ≤ 0.05) compared to chemical AgNPs and commercial antibiotics.
• Lower MIC50 values were observed for green AgNPs (46.10 μg mL⁻¹ for S. aureus, 49.93 μg mL⁻¹ for E. coli) versus chemical AgNPs (77.39 μg mL⁻¹ for S. aureus, 86.50 μg mL⁻¹ for E. coli).
• Green synthesized AgNPs exhibited superior cell viability in RAW264.7 cell assays.

Conclusions:

• Green synthesized AgNPs, derived from Citrus limon, are effective antimicrobial agents against Staphylococcus aureus and Escherichia coli.
• The eco-friendly synthesis approach yields AgNPs with enhanced antimicrobial potency and better biocompatibility compared to chemical synthesis.
• Green synthesized AgNPs represent a promising, potentially superior alternative to current commercial antibiotics for treating bovine mastitis.