Biogenic synthesis of Bacillus lentus-mediated silver nanoparticles and its multifaceted applications in antibacterial, anti-biofilm, anti-larvicidal and anticancer activities

Abstract

This study investigates the biogenic synthesis of silver nanoparticles (AgNPs) using Bacillus lentus, chosen for its probiotic properties and the polysaccharides in its cell walls, which facilitate nanoparticle formation. The AgNPs were characterized through UV-Vis spectroscopy, FTIR, XRD, and SEM, confirming their spherical shape, crystalline structure, and stabilization by bacterial metabolites. Their antimicrobial activity was tested against aquatic pathogens such as Bacillus licheniformis and Pseudomonas aeruginosa, revealing significant antibacterial effects, particularly against P. aeruginosa, and disrupting biofilm formation. The nanoparticles also demonstrated strong antioxidant capacity in DPPH assays, potent larvicidal effects against Culex species at a concentration of 60 ppm, and downregulated prophenoloxidase gene expression, indicating reduced disease progression in AHPND-infected shrimp. Additionally, in anticancer assays, the AgNPs effectively reduced the viability of MDA MB-231 breast cancer cells, inducing apoptosis primarily through ROS generation. These results suggest that B. lentus-mediated AgNPs are eco-friendly, multifunctional nanomaterials with potential applications in antimicrobial, antioxidant, anticancer, and larvicidal treatments, highlighting their promising role in aquaculture, healthcare, and environmental management.

Keywords

• Silver nanoparticles
• Bacillus lentus
• green synthesis
• antimicrobial activity
• anti-cancer therapy