Exploring multiple effects of Zn0.15Mg0.85O nanoparticles on Bacillus subtilis and macrophages

Abstract

The increasing number of multidrug resistant bacteria raises a serious public-health concern, which is exacerbated by the lack of new antibiotics. Metal oxide nanoparticles are already applied as an antibacterial additive in various products used in everyday life but their modes of action have remained unclear. Moreover, their potential negative effects to human health are still under evaluation. We explored effects of mixed metal oxide Zn0.15Mg0.85O on Bacillus subtilis, as a model bacterial organism, and on murine macrophages. Zn0.15Mg0.85O killed planktonic bacterial cells and prevented biofilm formation by causing membrane damages, oxidative stress and metal ions release. When exposed to a sub-inhibitory amount of Zn0.15Mg0.85O, B. subtilis up-regulates proteins involved in metal ions export, oxidative stress response and maintain of redox homeostasis. Moreover, expression profiles of proteins associated with information processing, metabolism, cell envelope and cell division were prominently changed. Multimode of action of Zn0.15Mg0.85O suggests that no single strategy may provide bacterial resistance. Macrophages tolerated Zn0.15Mg0.85O to some extend by both the primary phagocytosis of nanoparticles and the secondary phagocytosis of damaged cells. Bacterial co-treatment with ciprofloxacin and non-toxic amount of Zn0.15Mg0.85O increased antibiotic activity towards B. subtilis and E. coli.

Activity evaluation of pure and doped zinc oxide nanoparticles against bacterial pathogens andSaccharomyces cerevisiae

“…The combustion method was used to produce ZnO‐1 and mixed Zn‐MgO, as described previously (Vidic et al ). Chemical vapour synthesis was applied to produce ZnO‐2 and Zn‐MgO (Zn 1‐x Mg x O, x = 0·85) as described by Auger et al (). ZnO‐1, ZnO‐2 NPs and mixed ZnMgO had average diameters between 50 and 100 nm, while that of Zn‐MgO was 5–10 nm in diameter.…”

Synthesis and antibacterial activity of iron manganite (FeMnO3) particles against the environmental bacteriumBacillus subtilis

“…For instance, MgO and CaO particles can generate singlet oxygen, ZnO can generate H 2 O 2 and OH À , while CuO and ZnMgO particles can produce all types of ROS. 5,7,8 We performed the XTT test to verify whether FeMnO 3 particles generate ROS in aqueous solutions. The reduction of XTT by O 2 c À ions results in formation of the orange-coloured XTT-formazan which adsorbs at 470 nm.…”

“…49 Mixed Mg-ZnO nanoparticles had multimode action on B. subtilis cells. 8 Besides the expected bacterial reaction to oxidative stress, B. subtilis had modied expression proles of proteins associated with information processing, metabolism, cell envelope and cell division. 8 To the best of our knowledge, there is no prior report about the prevalent ROS generated, nor metal ion released in aqueous solutions of FeMnO 3 particles.…”

“…8 Besides the expected bacterial reaction to oxidative stress, B. subtilis had modied expression proles of proteins associated with information processing, metabolism, cell envelope and cell division. 8 To the best of our knowledge, there is no prior report about the prevalent ROS generated, nor metal ion released in aqueous solutions of FeMnO 3 particles. We conducted the study without any bias and found out that, (i) various ROS can be generated, and (ii) both metal ion release and ROS production strongly depended on the surrounding medium.…”

“…2,7 Highly reactive ROS can be produced on the surface of metal oxide particles with or without UV illumination. 5,8,9 ROS-induced damages and bacterial death comprise cell metabolite perturbation, oxidative lesions and membrane impairment by lipid peroxidation resulting in cell leakage. In addition, ROS can damage bacterial components such as surface proteins and nucleic acids.…”