title: Antibacterial activity and mechanism of action of zinc oxide nanoparticles against Campylobacter jejuni.
abstract: The antibacterial effect of zinc oxide (ZnO) nanoparticles on Campylobacter jejuni was investigated for inhibition and inactivation of cell growth. The results showed that C. jejuni was extremely sensitive to treatment with ZnO nanoparticles. The MIC of ZnO nanoparticles for C. jejuni was determined to be 0.05 to 0.025 mg/ml, which is 8- to 16-fold lower than that for Salmonella enterica serovar Enteritidis and Escherichia coli O157:H7 (0.4 mg/ml). The action of ZnO nanoparticles against C. jejuni was determined to be bactericidal, not bacteriostatic. Scanning electron microscopy examination revealed that the majority of the cells transformed from spiral shapes into coccoid forms after exposure to 0.5 mg/ml of ZnO nanoparticles for 16 h, which is consistent with the morphological changes of C. jejuni under other stress conditions. These coccoid cells were found by ethidium monoazide-quantitative PCR (EMA-qPCR) to have a certain level of membrane leakage. To address the molecular basis of ZnO nanoparticle action, a large set of genes involved in cell stress response, motility, pathogenesis, and toxin production were selected for a gene expression study. Reverse transcription-quantitative PCR (RT-qPCR) showed that in response to treatment with ZnO nanoparticles, the expression levels of two oxidative stress genes (katA and ahpC) and a general stress response gene (dnaK) were increased 52-, 7-, and 17-fold, respectively. These results suggest that the antibacterial mechanism of ZnO nanoparticles is most likely due to disruption of the cell membrane and oxidative stress in Campylobacter.
authors.affiliation: Joint Sino-U.S. Food Safety Research Center & Bor Luh Food Safety Center, School of Agriculture & Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, China 200240.
authors.forename: Yanping
authors.initials: Y
authors.lastname: Xie
authors.forename: Yiping
authors.initials: Y
authors.lastname: He
authors.forename: Peter L
authors.initials: PL
authors.lastname: Irwin
authors.forename: Tony
authors.initials: T
authors.lastname: Jin
authors.forename: Xianming
authors.initials: X
authors.lastname: Shi
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D016123:Campylobacter jejuni / Q000187:drug effects* / Q000254:growth & development; D002463:Cell Membrane Permeability / Q000187:drug effects; D019453:Escherichia coli O157 / Q000187:drug effects / Q000254:growth & development; D020869:Gene Expression Profiling; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects; D053758:Nanoparticles; D018384:Oxidative Stress; D012477:Salmonella enteritidis / Q000187:drug effects / Q000254:growth & development; D015034:Zinc Oxide / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D015034:Zinc Oxide