Toxicity of ZnO Nanoparticles to Escherichia coli: Mechanism and the Influence of Medium Components

• Published in: Environmental science & technology Vol. 45; no. 5; pp. 1977 - 1983
• Main Authors: Li, Mei, Zhu, Lizhong, Lin, Daohui
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.03.2011
• Subjects: Action of physical and chemical agents on bacteria; Amino acids; Anti-Bacterial Agents - toxicity; Bacteriology; Biological and medical sciences; Dose-Response Relationship, Drug; E coli; Ecotoxicology and Human Environmental Health; Escherichia coli - drug effects; Fresh Water - chemistry; Fundamental and applied biological sciences. Psychology; Ions; Metal Nanoparticles - toxicity; Microbiology; Nanoparticles; Physical chemistry; Toxicity; Water; Water Pollutants, Chemical - toxicity; Zinc Oxide - toxicity; Zinc oxides; Nanoparticle; Toxicity; Escherichia coli; Bacteria; Biological activity; Zinc; Enterobacteriaceae; Heavy metal
• ISSN: 0013-936X; 1520-5851; 1520-5851
• DOI: 10.1021/es102624t

Water chemistry can be a major factor regulating the toxicity mechanism of ZnO nanoparticles (nano-ZnO) in water. The effect of five commonly used aqueous media with various chemical properties on the toxicity of nano-ZnO to Escherichia coli O111 (E. coli) was investigated, including ultrapure water, 0.85% NaCl, phosphate-buffered saline (PBS), minimal Davis (MD), and Luria−Bertani (LB). Combined results of physicochemical characterization and antibacterial tests of nano-ZnO in the five media suggest that the toxicity of nano-ZnO is mainly due to the free zinc ions and labile zinc complexes. The toxicity of nano-ZnO in the five media deceased as follows: ultrapure water > NaCl > MD > LB > PBS. The generation of precipitates (Zn3(PO4)2 in PBS) and zinc complexes (of zinc with citrate and amino acids in MD and LB, respectively) dramatically decreased the concentration of Zn2+ ions, resulting in the lower toxicity in these media. Additionally, the isotonic and rich nutrient conditions improved the tolerance of E. coli to toxicants. Considering the dramatic difference of the toxicity of nano-ZnO in various aqueous media, the effect of water chemistry on the physicochemical properties of nanoparticles should be paid more attention in future nanotoxicity evaluations.