摘要

       据报道，新出现的污染物，例如工程金属氧化物纳米粒子 (NPs) 和抗生素抗性基因 (ARGs)，在废弃活性污泥中积累。在这项研究中，评估了 CuO 和 ZnO NPs 对污泥厌氧消化过程中 ARGs 命运的潜在影响。宏基因组结果表明，CuO 或 ZnO NPs 的存在增加了 ARG 丰度，但对耐药机制和类型的百分比没有显着影响。宏基因组的进一步功能分析表明，信号转导受到两种 NP 的刺激，尤其是负责群体感应 (QS)、菌毛合成和金属耐受性的双组分调节系统 (TCRS)。此外，发现激活的 QS 与转移的细菌群落密切相关，特别是富集的属，如酸食菌属、伯克霍尔德菌属、假单胞菌属和红杆菌属，它们不仅是 QS 信号的产生者，也是 ARGs 的宿主。同时，触发菌毛合成，结合可移动遗传元件（质粒、整合子和插入序列）丰度的增加，将促进 ARG 在不同细菌之间的转移。此外，对铜/锌和其他金属（如汞和砷）的诱导抗性可能促进了金属和抗生素抗性之间的共同选择。上述结果表明 ARGs 在消化器中的传播可能是由 NP 刺激的信号转导驱动的。这些发现可能为理解 ARG 对不同环境刺激的反应带来新的见解。

       Emerging contaminants, such as engineered metal oxide nanoparticles (NPs) and antibiotic resistance genes (ARGs), were reported to be accumulated in waste activated sludge. In this study, the potential impacts of CuO and ZnO NPs on the fate of ARGs during sludge anaerobic digestion were assessed. Metagenomic results showed that the presence of CuO or ZnO NPs increased ARG abundance but had no significant effects on the percentages of resistance mechanisms and types. Further functional analysis of the metagenomes revealed that signal transduction was stimulated by both NPs, especially two-component regulatory systems (TCRS) responsible for quorum sensing (QS), pili synthesis and metal tolerance. Moreover, it was found that the activated QS was closely associated with the shifted bacterial communities, especially enriched genera, such as Acidovorax, Burkholderia, Pseudomonas and Rhodobacter, which were not only the producers of QS signals but also the hosts of ARGs. Meanwhile, the triggered pili synthesis, combined with the increased abundance of mobile genetic elements (plasmids, integrons and insertion sequences), would facilitate the transfer of ARGs among diverse bacteria. Furthermore, the induced resistance to copper/zinc and other metals, such as mercury and arsenic, probably promoted the co-selection between metal and antibiotic resistance. The above results indicated that the propagation of ARGs in digesters might be driven by the NP-stimulated signal transduction. These findings may bring new insights into the understanding of ARG responses to diverse environmental stimuli.

https://pubs.rsc.org/fa/content/articlelanding/2019/en/c8en00370j/unauth#!divAbstract