Antimicrobial Effect of Silver Nanoparticles Capped with Killer Yeast-Derived Protein Fractions

Recently, novel nanobiotechnological approaches have been developed to reduce the impact of pollutants during the synthesis of nanoparticles (NPs). To do so, green synthesis methods have now become widely adopted, using biomolecules to produce high-quality, stable nanoparticles. In this work, we employed the K1 toxin produced by S. cerevisiae as a reducing and capping agent for silver nanoparticles. The synthesis of Ag-K1 NPs was carried out using a concentrated protein fraction from the culture medium of S. cerevisiae 42300 containing the secreted K1 toxin. The obtained nanoparticles were characterized using UV–Vis spectroscopy, STEM, EDS, and FTIR, and the antimicrobial efficacy was determined against S. cerevisiae, P. aeruginosa, and B. subtilis. The synthesized NPs showed high antimicrobial efficacy, killing all tested strains; additionally, dose–response modeling suggested differential activity among the nanoparticles. This work reports, for the first time, the bio-assisted synthesis and antimicrobial characterization of silver nanoparticles associated with K1 killer toxin-containing protein fractions.