To understand the effects of metal ions and nanoparticles (NPs) on nitrifying bacterial communities, this study investigates the impacts of zinc (Zn) NPs, zinc oxide (ZnO) NPs and Zn ions on the nitrifying bacterial communities. Under low Zn concentration (0.1 mg L⁻¹), the nitrification rate was promoted by Zn ions and inhibited by the two NPs, indicating that the toxicity of NPs was caused by the NPs themselves instead of the released Zn ions. Further analysis showed that both Zn NPs and ZnO NPs could result in substantial reactive oxygen species (ROS) production in the nitrifying bacteria community. The inhibition was strongly correlated with amoA gene expression, but not with the expression of hao and nxrA genes. These results indicated that the main difference of the Zn ions and Zn NPs on nitrifying bacterial community could be due to the different impacts on the ROS production and amoA gene expression. Collectively, the findings in this study advanced understanding of the different effects of Zn NPs, ZnO NPs and Zn ions on nitrifying bacteria.

中文翻译：

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锌离子和锌纳米颗粒对硝化微生物群落影响的比较

为了了解金属离子和纳米颗粒（NPs）对硝化细菌群落的影响，本研究调查了锌（Zn）NPs，氧化锌（ZnO）NPs和Zn离子对硝化细菌群落的影响。在低锌浓度（0.1 mg L ^-1）下，硝化速率被锌离子促进，并被两个NPs抑制，表明NPs的毒性是由NPs本身而不是由释放的Zn离子引起的。进一步的分析表明，Zn NP和ZnO NP均可导致硝化细菌群落中大量的活性氧（ROS）产生。抑制作用与amo A基因表达密切相关，而与hao和nxr表达无关一个基因。这些结果表明，Zn离子和Zn NPs在硝化细菌群落上的主要差异可能是由于对ROS产生和amo A基因表达的不同影响。总体而言，这项研究的发现进一步了解了Zn NP，ZnO NP和Zn离子对硝化细菌的不同影响。