Molecular identification, characterization and antibacterial activity of fungal-mediated silver nanoparticles against Bacillus subtilis sh3 and Klebsiella pneumoniae sh4.

The increasing prevalence of multidrug-resistant bacteria has created a determined need for new antimicrobial approaches. In the present study, Fusarium oxysporum SH1 was utilized as a biological source for the green synthesis of silver nanoparticles through its extracellular metabolites. The produced nanoparticles were confirmed to form within the nanoscale range and exhibited stable physicochemical characteristics. They showed clear antibacterial activity against two multidrug-resistant clinical isolates, Bacillus subtilis sh3 and Klebsiella pneumoniae sh4, with low minimum inhibitory concentrations. In addition, combining the nanoparticles with commonly used antibiotics enhanced the inhibition zones compared with the use of either agent alone, indicating a measurable improvement in antibacterial performance. The biosynthesized nanoparticles also demonstrated selective cytotoxic effects when tested on human cell lines. MCF7 breast cancer cells exhibited a markedly lower IC50 value than normal HFB4 melanocytes, and treatment was associated with distinct morphological alterations indicative of compromised cell structure. These findings indicate a stronger growth-inhibitory effect on malignant cells under the tested conditions. Generally, this study presents a straightforward and eco-friendly method for producing biologically active silver nanoparticles using F. oxysporum SH1. The nanoparticles displayed dual biological functions as antibacterial activity against resistant pathogens and selective cytotoxicity toward cancer cells. These experimentally supported observations suggest that fungal-mediated silver nanoparticles represent a promising candidate for further investigation in antimicrobial and anticancer applications.