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.

Desertifilum sp. EAZ03 cell extract as a novel natural source for the biosynthesis of zinc oxide nanoparticles and antibacterial, anticancer and antibiofilm characteristics of synthesized zinc oxide nanoparticles.

AIMS: The use of cyanobacterial cell extracts for the synthesis of zinc oxide nanoparticles (ZnO NPs) seems to be superior to other methods of synthesis because of its a green, environmentally friendly and low-cost approach. In this study, the cell extract of a newly characterized cyanobacterial strain Desertifilum sp. EAZ03 was used for the biosynthesis of ZnO NPs. The antimicrobial, antibiofilm and anticancer activities of the biosynthesized ZnO NPs (hereinafter referred to as CED-ZnO NPs) were examined as well. METHODS AND RESULTS: UV-Vis spectroscopy analysis of CED-ZnO NPs showed an absorbance band at 364 nm, and powder X-ray diffraction analysis confirmed the purity of the synthesized nanoparticles. The analyses of scanning electron microscopy and transmission electron microscopy images revealed that CED-ZnO NPs were rod-shaped with a size of 88 nm. The study of the biological features of CED-ZnO NPs showed a significant antimicrobial potential against the bacterial strains tested. CED-ZnO NPs were able to impede the biofilm formation by Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa up to 80%, 89% and 85%, respectively. The nanoparticles also showed 69%, 70% and 62% degrading activity against S. aureus, E. coli and P. aeruginosa 1-day-old biofilms, respectively. The antibiofilm activity of the synthesized nanoparticles was investigated by confocal laser scanning microscopy. The MTT assay showed that CED-ZnO NPs, at a concentration of 100 µg/ml, had less cytotoxicity towards normal lung (MRC-5) cells, at the half, compared to cancerous lung alveolar epithelial (A549) cells. The minimum inhibitory concentration and minimum bactericidal concentration values of CED-ZnO NPs against E. coli, P. aeruginosa and S. aureus were 1500, 2000 and 32 µg/ml, and 2500, 3500 and 64 µg/ml, respectively. CONCLUSIONS: The multifunctional CED-ZnO NPs seem to be promising for possible applications in the therapeutic and pharmaceutical industries. SIGNIFICANCE AND IMPACT OF THE STUDY: This study proposes a new approach for the biosynthesis of zinc oxide nanoparticles using a newly characterized cyanobacterial strain Desertifilum sp. EAZ03. The considerable antimicrobial, antibiofilm and anticancer activities of the biosynthesized zinc oxide nanoparticles further emphasize the emerging role of microbial systems in the green synthesis of metal oxide nanoparticles.

Evaluation of Gamma Irradiation Effect on the Oxidative Stress Factors in Septic Rats Treated With Iranian Plant Essential Oils

ABSTRACT Cuminum cyminum L. (CM), Zataria multiflora Boiss. (ZM) and Mentha piperita L. (MP) are traditional medicinal plants with various pharmacological properties. This study was designed to assess the role of gamma irradiation -a modern decontamination method- in hepatoprotective effects of their essential oil (E.Os) in septic rats induced by experimental cecal ligation and puncture (CLP) model. The rats were divided into 20 groups; sham-operated (SOP); CLP; CLP + CM, ZM and MP (E.Os) (100 & 200 mg/kg b.w) and CLP + gamma irradiated (10 and 25 kGy) E.Os (100 & 200 mg/kg b.w) as treatment groups. All E.Os were injected i.p immediately after sepsis induction. 24 hour after CLP, the rats were sacrificed and the liver tissue was examined considering lipid peroxiation (LP), glutathione (GSH) and myeloperoxidase (MPO) activity. The results indicated that CLP operation caused significant (P<0.05) increase in the LP and MPO levels concomitant with decreased GSH level. Administration of the E.Os (100 and 200 mg/kg b.w) extracted from non irradiated plants as well as the irradiated (10 and 25 kGy) plant E.Os could significantly (P<0.05) modulate the levels of LP, MPO and GSH. It can be concluded that all E.Os even after irradiation exposure could modulate the oxidative injury parameters related to liver damages in CLP rat model. In conclusion, the plant irradiation didn't have any adverse effects on the hepatoprotective activities of the extracted oils.