TAGRA 2025

Postbiotics are compounds formed after metabolic processes of probiotic microorganisms and have the potential to exert positive health effects. Nanoparticles are carriers, designed at the molecular level, capable of exerting targeted effects. The food industry utilizes zinc oxide (ZnO), a source of zinc, as an essential micronutrient and is listed as a Generally Recognized As Safe (GRAS) material by the Food and Drug Administration (FDA). The aim of this study was to produce ZnO nanoparticles using a postbiotic obtained from Lactobacillus plantarum ACC54 strain via green synthesis and to determine the antimicrobial and antioxidant activities of the synthesized nanoparticles. In this study, L. plantarum ACC54 strain was grown in MRS broth and banana peel-enriched medium to obtain two different postbiotics. ZnO nanoparticles were synthesized via hydrothermal green synthesis using postbiotics as reducing agents. The obtained nanoparticles were characterized for their morphological and structural properties by X-Ray Diffraction, Scanning Electron Microscopy, and Fourier Transform Infrared Spectrophotometer analyses. Antimicrobial activity was determined by the Agar Well Diffusion method, and antioxidant activity was determined by the KUPRAK (Cu2+-Cu+ Reducing Activity) method and 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging tests. Characterization analyses confirmed that the synthesized ZnO nanoparticles were crystalline, nano-sized, and postbiotic-coated. The bioactivity of the ZnO NPs obtained by enriching the obtained postbiotics with prebiotics was investigated. Antioxidant analyses (DPPH and KUPRAK) showed that the nanolabeling process altered the mechanism of action of the postbiotics, and that the new generation nanocarriers, especially in terms of KUPRAK reducing activity, possessed high antioxidant potential. On the other hand, antimicrobial activity was found to be limited in most of the tested strains. These findings indicate that postbiotics from L. plantarum ACC54 can be used as effective reducing biocatalysts in the synthesis of ZnO nanoparticles, and these nanomaterials hold promise for biomedical applications and functional foods.