Biosynthesis of Zinc Oxide Nanoparticles by Lactobacillus spp. and Investigation of their Antimicrobial Effect

Background: Nanoparticle biology is preferable to other common methods due to its economic efficiency and compatibility with the environment. On the other hand, the prevalence of drug-resistant bacterial strains is expanding and it is necessary to use alternative antibiotic compounds to deal with them. The aim of the present study was the biosynthesis of zinc oxide nanoparticles(ZnO NPs) by Lactobacillus spp. and their antimicrobial effect. Methods: In this study, after the biosynthesis of ZnO NPs by Lactobacillus spp, Characterization of Nanoparticulation Was performed by UV–Vis, XRD, and Scanning Electron Microscopy (SEM). Additionally, Lactobacillus spp. - ZnO NPs were assessed for their antimicrobial properties. Results: UV-visible spectroscopy confirmed the Lactobacillus spp. - ZnO NPs absorbed UV in the region of 300-400 nm. XRD analysis showed the presence of zinc metal in nanoparticles. SEM revealed that Lactobacillus plantarum - ZnO NPs were smaller than the others. Staphylococcus aureus showed the largest non-growth halo diameter against ZnO NPs synthesized by L. plantarum ATCC 8014 (3.7 mm). E. coli had the largest growth halo diameter against ZnO NPs synthesized by L. casei (3 mm) and L. plantarum (2.9 mm). The MIC values of ZnO NPs synthesized by L. plantarum ATCC 8014, L.casei ATCC 39392, L. fermenyum ATCC 9338, L. acidophilus ATCC 4356 were 2,8,8 and 4 μg/mL for Staphylococcus aureus. The MIC values of ZnO NPs synthesized by L. plantarum ATCC 8014, L. casei ATCC 39392, L. fermenyum ATCC 9338, L. acidophilus ATCC 4356 were 2, 4, 4, and 4 μg/ml for E. coli. The lowest MICs were 2 μg/ml for E. coli and S. aureus related to ZnO NPs synthesized by L. plantarum ATCC 8014. MIC and MBC values were equivalent to each other. Conclusion: The results of this research show that ZnO NPs synthesized by L. plantarum ATCC 8014 have more antimicrobial effects than other ZnO NPs used. Therefore, the ZnO NPs made with Lactobacillus plantarum ATCC 8014 have the potential to kill bacteria and can be considered a candidate for antibiotic replacement.