Exogenous Fe²⁺ alleviated the toxicity of CuO nanoparticles on Pseudomonas tolaasii Y-11 under different nitrogen sources

Abstract

Extensive use of CuO nanoparticles (CuO-NPs ) inevitably leads to their accumulation in wastewater and toxicity to microorganisms that effectively treat nitrogen pollution. Due to the effects of different mediums, the sources of CuO-NPs-induced toxicity to microorganisms and methods to mitigating the toxicity are still unclear. In this study, CuO-NPs were found to impact the nitrate reduction of Pseudomonas tolaasii Y-11 mainly through the action of NPs themselves while inhibiting the ammonium transformation of strain Y-11 through releasing Cu2+. As the content of CuO-NPs increased from 0 to 20 mg/L, the removal efficiency of NO3− and NH4+ decreased from 42.29% and 29.83% to 2.05% and 2.33%, respectively. Exogenous Fe2+ significantly promoted the aggregation of CuO-NPs, reduced the possibility of contact with bacteria, and slowed down the damage of CuO-NPs to strain Y-11. When 0.01 mol/L Fe2+ was added to 0, 1, 5, 10 and 20 mg/L CuO-NPs treatment, the removal efficiencies of NO3- were 69.77%, 88.93%, 80.51%, 36.17% and 2.47%, respectively; the removal efficiencies of NH4+ were 55.95%, 96.71%, 38.11%, 20.71% and 7.43%, respectively. This study provides a method for mitigating the toxicity of CuO-NPs on functional microorganisms.

Fe2+ Alleviated the Toxicity of ZnO Nanoparticles to Pseudomonas tolaasii Y-11 by Changing Nanoparticles Behavior in Solution

“…Previous studies showed that Fe 2+ could alleviate the cytotoxicity of CuO-NPs [23]. To determine the universality of Fe 2+ to alleviate the cytotoxicity of NPs, we further explored the effect of Fe 2+ on the cytotoxicity of ZnO-NPs.…”

“…Purity ZnO-NPs (20 nm, 99.9%, Zewu Company, Chongqing, China) were used in this study. ZnO-NPs (100 mg) were dispersed in 50 mL ultrapure water, and the suspension was prepared by ultrasonic (600 W and 40 kHz) for 20 min according to the method previously studied [23]. The Zeta potential was measured with a Zeta potential analyzer (ZetaPlus, Brookhaven, NY, USA) (Table S1).…”