Biosynthesis of silver nanoparticles by Kurthia gibsonii: Molecular docking and pathogenicity insights

The increasing emergence of antimicrobial resistance (AMR) has heightened the need for novel antimicrobial agents. Silver nanoparticles (AgNPs) have gained attention due to their broad-spectrum activity against bacteria and fungi, but conventional synthesis methods involve toxic chemicals. This study explores the biosynthesis of AgNPs using the silver-tolerant bacterium Kurthia gibsonii, isolated from rhizosphere soil in the Jazan region of Saudi Arabia. Kurthia gibsonii demonstrated robust growth in the presence of 2.0 mM AgNO₃, indicating its ability to reduce silver ions to nanoparticles. The biosynthesized AgNPs were characterized using UV-Vis spectroscopy, SEM, TEM, XRD, and FTIR, confirming the successful synthesis of spherical, crystalline nanoparticles with sizes ranging from 10 to 30 nm. The antimicrobial activity of AgNPs was evaluated against Gram-positive, Gram-negative bacteria, and fungi, with significant inhibition observed, particularly against Bacillus subtilis and Candida albicans. Molecular docking studies revealed that AgNPs interact with critical proteins involved in DNA replication, cell division, and membrane integrity, providing insights into their multi-target antimicrobial action. This study highlights the potential of Kurthia gibsonii-mediated AgNPs as eco-friendly antimicrobial agents with applications in nanomedicine and agriculture.