Streptomyces pratensis-Mediated Fabrication of Silver Nanoparticles and Its Applications as Antimicrobial and Anticancer

The recent emergence of drug-resistant microorganisms and the prevalence of cancer diseases are both presenting substantial global public health concerns. Silver nanoparticles (AgNPs) have attracted significant attention and are increasingly employed in diverse biomedical applications as agents with antimicrobial and anticancer properties. The study herein focused on the biogenic synthesis of AgNPs employing the cell-free filtrate of the soil-derived bacterium Streptomyces pratensis as a reducing agent. AgNPs were characterized using UV–Vis, FTIR, FE-SEM, and TEM. The study assessed both the antibacterial and anticandidal modes of action, along with the potential anticancer properties of the biosynthesized AgNPs. The spherical, 17–44-nm biosynthesized AgNPs demonstrated strong antimicrobial and antibiofilm activities against pandrug-resistant (PDR) Gram-negative Klebsiella pneumoniae and pathogenic yeast Candida albicans, both of which were isolated from immunosuppressed patients. Dose-dependent interactions between the AgNPs and their anticancer activity were observed. The IC values of the AgNPs against the hepatocellular (HepG2) and colon carcinoma (HCT-116) cancer cell lines were approximately 16.5 µg/mL and 11.5 µg/mL, respectively. Furthermore, the antimicrobial mechanism of action of AgNPs revealed distinct leakage of sugar, DNA, and proteins from the cell membrane of both K. pneumoniae and C. albicans, as well as increased ROS generation. Moreover, the TEM micrographs depicted the distortion and damage experienced by the microbial cells after exposure to AgNPs. The findings of the current study suggest that biosynthesized AgNPs have the potential to serve as alternative therapeutic agents for combating drug-resistant K. pneumoniae, the yeast C. albicans, in addition to HepG2 and HCT-116 cells.