Use of silver nanoparticles synthesized using probiotic microorganism culture filtrate in whey protein films

In this study, extracellular AgNPs were synthesized from the culture filtrate of the most commonly used probiotic microorganisms (Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactobacillus casei, Bacillus coagulans, Sacharomyces boulardi). The synthesized AgNPs were characterized using UV-Visible spectrophotometer (UV-Vis.), Scanning Electron Microscope (SEM), X-ray Diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR) techniques. Biogenic AgNPs were incorporated into edible films produced with whey protein at varying ratios, and the antimicrobial properties of the films were determined using the agar disc diffusion method. As a result of the research, stable AgNPs were synthesized from the culture supernatants of probiotic microorganisms. Following the synthesis stages, the absorbance of the brown NP colloidal solutions was evaluated by UV-Vis spectrophotometry, and the peak absorbance values corresponding to the surface plasmon resonance of AgNPs were found to be at 402 nm and 425 nm. SEM analysis confirmed the formation of spherical AgNPs with an average diameter ranging from 10-35 nm from all probiotic species. XRD analysis, with the highest intensity peak data read at 2θ, corresponded to the (111), (200), (220), and (311) lattice planes of face-centered cubic silver, confirming the presence of cubic silver crystals consistent with the JCPDS standard silver diffraction card. FTIR analysis identified proteins as the functional groups responsible for the reduction of AgNPs. After 24 hours of incubation, AgNPs exhibited antimicrobial effects against E. coli, S. aureus, L. monocytogenes, P. chrysogenum, and S. Cerevisiae microorganisms, while edible films containing AgNPs did not show a significant inhibition zone, suggesting that AgNPs were not released from the films.