Eco-Friendly Synthesis of Silver Nanoparticles Using Klebsormidium subtile and Evaluation of their Antimicrobial, Anti-Quorum Sensing, and Antibiofilm Activities

In this study, both dry and fresh biomass extracts of Klebsormidium subtile were used for the synthesis of silver nanoparticles (AgNPs). The UV-visible spectrum showed an absorption peak at 430 nm, indicating the presence of AgNPs through surface plasmon resonance. FT-IR analysis identified bioactive functional groups, such as amines, which acted as stabilizing agents for the nanoparticles. SEM imaging revealed well-dispersed, spherical AgNPs ranging from 5 to 25 nm and 40 to 60 nm in size, accumulating on cell surfaces. EDS analysis confirmed the presence of elemental silver. The antimicrobial activity of AgNPs derived from both fresh and dry K. subtile extracts was similar, though AgNPs from the dry extract were more effective against Staphylococcus aureus, with inhibition zones of 15.8, 16.2, and 15.2 mm at 1 mM, 2 mM, and 3 mM concentrations, respectively. AgNPs also showed strong activity against Bacillus subtilis, Pseudomonas aeruginosa, and Candida albicans, but were less effective against Bacillus cereus and Aeromonas hydrophila. These findings suggest that K. subtile-derived AgNPs have significant antimicrobial potential, particularly against S. aureus and C. albicans, and may be useful in biomedical applications, particularly for treating biofilm-related infections.