Transcriptional responses of continuously cultured Nitrosomonas europae to chonic TiO2 nanoparticle stress

To further explore the biotoxicity mechanisms of TiO2 nanoparticles (NPs) and the recovery potentials of the impaired Nitrosomonas europaea (N. europaea, ATCC 19718) cells, a genome-sequenced model ammonia oxidizing bacterium (AOB) commonly detected in the activated sludge of biological wastewater treatment plants, the whole-genome microarray analysis was applied to retrieve the induced transcriptional responses during the long-term exposure, after the toxicity effects and the recovery potentials were assessed at both physiological and metabolic levels. The whole-genome expressions were measured after 12-d and 40-d exposure to 50 ppm TiO2 NPs in the chemostat bioreactor, respectively.Three independent experiments were performed for each experiment.