Transcriptomics uncover the response of an aerobic denitrifying bacteria to zinc oxide nanoparticles exposure.

ABSTRACT

Zinc oxide nanoparticles (ZnO NPs) show adverse impacts on aerobic denitrifying bacteria, little is known about the response of these bacteria to ZnO NPs exposure at cellular level. This study assessed the multiple responses of Pseudomonas aeruginosa PCN-2 under ZnO NPs exposure. We demonstrated that ZnO NPs exposure could inhibit the intracellular metabolism and stimulate the antioxidant defence capability of PCN-2. At lower exposure concentration (5 mg/L), exogenous ROS generated and resulted in the inhibition of pyruvate metabolism and citrate cycle, which caused deficient energy for aerobic denitrification. At higher concentrations (50 mg/L), endogenous ROS additionally generated and triggered to stronger down-regulation of oxidative phosphorylation, which caused suppressed electron transfers for aerobic denitrification. Meanwhile, ZnO NPs exposure promoted EPS production and biofilm formation, and antioxidases was especially particularly stimulated at higher concentration. Our findings are significant for understanding of microbial bacterial susceptibility, tolerance and resistance under the exposure of ZnO NPs.

Aerobic denitrification is suppressed with increased ZnO NPs concentrations.ZnO NPs induce inhibition of pyruvate metabolism and citrate cycle at 5 mg/L.Higher ZnO NPs concentration induces the generation of endogenous and exogenous ROS.Higher NPs concentration leads to the trigger of antioxidant system.ZnO NPs stimulate metabolisms of EPS production.