Silver Nanoparticles Derived from Probiotic Lactobacillus casei —a Novel Approach for Combating Bacterial Infections and Cancer

In the face of rising antibiotic resistance and the need for novel therapeutic approaches against cancer, the present study delves into the various facets of biosynthesized silver nanoparticles (AgNPs) derived from the probiotic strain Lactobacillus casei (AgNPs-LC), assessing their efficacy in combating bacterial infections, disrupting biofilm formation, interfering with quorum sensing mechanisms, and exhibiting anti-cancer properties. The results showed that the AgNPs-LC had a spherical shape with an average size of 15 nm. The biosynthesized AgNPs-LC showed a symmetrical absorption spectrum with a peak at 458 nm with a diameter of 5–20 nm. AgNPs-LC exhibited significant antibacterial activity against Gram-positive and Gram-negative bacteria and inhibited the biofilm formation (> 50% at sub-MIC) and quorum sensing-mediated virulence factors, such as the production of violacein in C. violaceum (> 80% at sub-MIC), pyocyanin in P. aeruginosa (> 70% at sub-MIC), and prodigiosin in S. marcescens (> 80% at sub-MIC). The exopolysaccharides (EPS) were also found to reduce in the presence of AgNPs-LC. Furthermore, the AgNPs-LC showed anti-cancer and anti-metastasis activity via inhibiting cell migration and invasion of human lung cancer (A-549) cells. Overall, the present study brings out the multifaceted therapeutic capabilities of AgNPs-LC which offer exciting prospects for the development of innovative biomedical and pharmaceutical interventions, making AgNPs-LC a versatile and promising candidate for a wide range of applications in healthcare and medicine. However, further research is essential to fully harness their therapeutic potential. Graphical Abstract