Characterization and Eco-friendly synthesis of silver nanoparticles by Bacillus Subtilis and their antibacterial activity | ||
| Microbes and Infectious Diseases | ||
| Articles in Press, Accepted Manuscript, Available Online from 12 October 2025 | ||
| Document Type: Original Article | ||
| DOI: 10.21608/mid.2025.420114.3176 | ||
| Authors | ||
| Nada Ahmed Fairooz1; Idrees A. A. Al-Bahathy2; Bushra Hamad Obaid1; Sura A Al-Ganahi* 3 | ||
| 1Polytechnic College, Al–Qadisiyah, Al-Furat Al- Awsat Technical University, Iraq | ||
| 2College of Engineering, AL-Qasim Green University, Babylon, Iraq | ||
| 3Department of Environmental Research and Pollution Prevention, College of Science, University of AL Qadisiya, Iraq | ||
| Abstract | ||
| Background: Antimicrobial resistance has created a pressing need for novel strategies to effectively control bacterial infections. One promising approach is the development of silver nanoparticles (AgNPs) through biological routes, considered safer and more sustainable than conventional chemical methods. Methods: The present work describes the biosynthesis of AgNPs using Bacillus subtilis (ATCC® 6051™) as a reducing and stabilizing agent. Characterization of the nanoparticles was carried out through UV–Vis spectrophotometry, Fourier-transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). The crystalline size was estimated by the Debye–Scherrer equation. Antibacterial activity of the synthesized AgNPs was assessed against Escherichia coli and compared with the reference antibiotic streptomycin. Results: UV–Vis spectra displayed a distinct surface plasmon resonance peak near 420 nm, confirming nanoparticle formation. AFM analysis indicated spherical particles, occurring singly or in clusters, with an average size of 44.2 nm and surface roughness of 206.8 nm. EDS revealed a strong silver signal at around 3 keV, while XRD profiles showed five characteristic peaks at 28.24°, 33.01°, 46.12°, 55.26°, and 58.06°, confirming a face-centered cubic crystalline structure. The Debye–Scherrer calculation yielded a crystal size of approximately 44.2 nm. Antibacterial testing demonstrated inhibition zones ranging from 27–32 mm for the AgNPs, which were comparable to or greater than those obtained with streptomycin (26–31 mm). Conclusion: Biogenically synthesized AgNPs from B. subtilis showed well-defined crystalline morphology and significant antibacterial activity. These findings highlight the potential of biosynthesized silver nanoparticles as an eco-friendly and effective alternative for managing bacterial pathogens. | ||
| Keywords | ||
| AgNPs; Antimicrobial activity; Bacillus subtilis; E coli; green biosynthesis | ||
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