Silver Nanoparticles Synthesized by Bacteria and Their Antimicrobial Activity

Document Type : Original Research Papers

Authors

1 botany (microbiology), collage of science, Banha university, Banha, Egypt

2 Botany and Microbiology Department, Faculty of Science, Benha University, Egypt

3 Microbial Chemistry department , National Research Centre , El Buhouth St. 33, Cairo 12622, Egypt

4 Professor of Botany and Microbiology Department , Faculty of Science, Benha University

5 Main laboratories for Egyptian Army

Abstract

Soil microbial communities play a crucial role in biotechnological applications, particularly in the process of making nanoparticles. Soil samples were obtained for this investigation from two different areas in Benha (SO1 and SO2) to isolate bacterial strains capable of synthesizing silver nanoparticles (AgNPs). There were ten of bacterial isolates collected, with six from SO1 and four from SO2. The ability of these isolates to synthesize AgNPs was assessed based on color change, indicating nanoparticle formation. Among them, SDO6 exhibited the highest biosynthetic activity (+++), suggesting a strong potential for silver ion reduction and nanoparticle stabilization.
The antibacterial ability of biosynthesized AgNPs from SDO6 was tested against Escherichia coli and Staphylococcus aureus, using ciprofloxacin (5 µg/mL) as a standard antibiotic. The results showed significant antibacterial effects, with an inhibition rate of 89.025% against E. coli, though slightly lower than ciprofloxacin (99.05%). In contrast, AgNPs exhibited a weaker inhibitory effect against S. aures (40.12%), compared to ciprofloxacin (98.25%). The higher susceptibility of E. coli suggests that AgNPs interact more effectively with Gram-negative bacterial membranes, leading to oxidative stress and cell disruption. The lower efficacy against S. aureus may be attributed to its thick peptidoglycan layer, this layer serves as a barrier against nanoparticle penetration.

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Benha Journal of Applied Sciences
Volume 10, Issue 2 - Serial Number 2
Applied and Basic Sciences:
February 2025
Pages 69-79

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