Combined effects of ZnO and TiO2 nanoparticles on functional gene expression of Nitrosomonas europaea. Nitrosomonas europaea ATCC 19718

To further explore and differentiate the biotoxicity mechanisms of individual nanoparticles (NPs) and NP mixture on Nitrosomonas europaea (N. europaea, ATCC 19718) at genetic level, a genome-sequenced model ammonia oxidizing bacterium (AOB) commonly detected in the activated sludge of biological wastewater treatment plants, the induced whole-genome expressions were analyzed with the high throughput Microarray technique, after the dose-dependent changes of N. europaea’s physiological, metabolic and AMO enzyme activities in single and dual component NP systems was evaluated. Overall design: NP stress induced gene expressions were measured after 6hr exposure to 10 ppm nano-ZnO, 50 nano-TiO2 and their mixture.Three independent experiments were performed for each experiment.