School of Agriculture and Food Sciences, The University of Queensland, St Lucia 4072, Queensland, Australia.
College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
Environ Sci Technol. 2020 Sep 15;54(18):11146-11154. doi: 10.1021/acs.est.0c01241. Epub 2020 Aug 27.
The accumulation of AgS in agricultural soil via application of Ag-containing sludge potentially affects the functioning of soil microorganisms and earthworms (EWs) due to the strong antimicrobial properties of Ag. This study examined the effects of AgS nanoparticles (AgS-NPs) on the EW-mediated ( and ) soil N cycle. We used 16S rRNA gene-based sequencing and quantitative polymerase chain reaction to examine the bacterial community and nitrification/denitrification-related gene abundance. The presence of either EWs or Ag significantly increased denitrification and NO emissions. However, the addition of AgS to EW-inhabited soil reduced NO emissions by 14-33%. Furthermore, AgS caused a low-dose stimulation but a high-dose inhibition to NO flux from the EW gut itself. Accordingly, an increase in Ag in the EW gut caused a decrease in the relative abundance of denitrifiers in both the soil and the gut, especially for the dominant genus . AgS also decreased the copy numbers of nitrification gene () and denitrification genes (, , and ) in EW gut, leading to the observed decrease in NO emissions. Collectively, applying AgS-containing sludge disturbs the denitrification function of the EW gut microbiota and the cycling of N in soil-based systems.
通过施用含银污泥，农业土壤中银的积累可能会影响土壤微生物和蚯蚓（EWs）的功能，因为银具有很强的抗菌性能。本研究考察了银纳米颗粒（AgS-NPs）对蚯蚓介导的（和）土壤氮循环的影响。我们使用基于 16S rRNA 基因的测序和定量聚合酶链反应来检测细菌群落和硝化/反硝化相关基因丰度。无论是 EWs 还是 Ag 的存在都显著增加了反硝化和 NO 排放。然而，在 EW 栖息土壤中添加 AgS 可将 NO 排放减少 14-33%。此外，AgS 对从 EW 肠道本身产生的 NO 通量产生低剂量刺激但高剂量抑制作用。因此，EW 肠道中 Ag 的增加导致土壤和肠道中反硝化菌的相对丰度降低，特别是对优势属。AgS 还降低了硝化基因（）和反硝化基因（、、和）在 EW 肠道中的拷贝数，导致观察到的 NO 排放减少。总的来说，施用含银污泥会干扰 EW 肠道微生物群的反硝化功能以及土壤基系统中氮的循环。
