Biosynthesis of Silver Nanoparticles Using Brevibacillus parabrevis OW4: Optimization, Characterization,
1Department of Biology, Division of Molecular Biology, Faculty of Science, Pamukkale University, Denizli, 20160, Türkiye.
Abstract:
The biosynthesis of silver nanoparticles (AgNPs) using eco-friendly approaches has emerged as an important area of research in nanobiotechnology. In this study, a sustainable approach for the green synthesis of AgNPs was investigated using silver nitrate (AgNO3) as a precursor and Brevibacillus parabrevis OW4 as an eco-friendly reducing and capping agent. Microbial-mediated AgNPs synthesis was carried out using a bacterial cell-free filtrate (CFF). Optimal synthesis conditions were established at pH 11, 2 mM AgNO3, and 72 h of incubation. Physicochemical characterization confirmed the formation of crystalline, spherical, polydisperse AgNPs with a surface plasmon resonance (SPR) peak at 400-440 nm and an average size of 58 ± 19 nm. The antibacterial and antibiofilm activities of the biogenic AgNPs were evaluated against Escherichia coli ATCC 10536, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 33862, and Enterococcus faecalis ATCC 19433. The results demonstrated that the biogenic AgNPs could effectively inhibit representative Gram-negative and Gram-positive human pathogens. The minimum inhibitory concentration (MIC) ranged from 7.8 ± 0.0 µg/mL to 31.2 ± 0.0 µg/mL, and the minimum bactericidal concentration (MBC) for all strains was 62.5 ± 0.0 µg/mL. Furthermore, this concentration was able to reduce more than 50% (p < 0.001) of biofilm formation, while 125 ± 0.0 µg/mL resulted in over 90% (p < 0.001) of biofilm formation inhibition in the tested strains. These findings demonstrate that B. parabrevis OW4-mediated AgNPs represent a promising, sustainable, and effective antimicrobial strategy. To the best of our knowledge, this study is the first to report the synthesis of AgNPs using B. parabrevis OW4, further emphasizing its novelty. The strong antibacterial and antibiofilm activities highlight their potential applications in combating biofilm-associated infections and support further investigation into their biomedical use.
