Biofilms are thought to be sinks for antibiotic resistance genes (ARGs) and nanoparticles (NPs), however, studies on the interactions between NPs and ARGs in biofilms are limited. This study focused on the occurrence and regulatory mechanisms of ARGs during the formation of biofilms with continuous treatment of zero-valent silver nanoparticles (Ag0-NPs) and Ag ions at an environmental concentration of 10 µg/L in the Yangtze Estuary. The biofilms could enrich large amounts of Ag, with the highest concentration of 97.60 mg/kg and 111.08 mg/kg in the Ag0-NPs and Ag ions group at 28 days. Compared to the blank at 28 days, the abundance of ARGs was reduced 2.2 times in the Ag0-NPs group, whereas it increased 1.3 times in the Ag ion group. Ag0-NPs and Ag ions induced the production of silver resistance genes (SRGs) or selected bacteria with SRGs in biofilms. Based on machine learning, the bacterial community, SRGs, and Ag concentration were the top three dominant regulators of ARGs, with 27.74 %, 25.57 %, and 17.93 % contributions, respectively. Structural equation modeling revealed that Ag could indirectly regulate ARGs by regulating the bacterial community in the Ag0-NPs group. Metagenomic sequencing further showed that most of the decreased ARGs were hosted by Betaproteobacteria in the Ag0-NPs groups. According to the KEGG pathway database, the possible molecular mechanism of Ag0-NPs/Ag ions regulating ARGs may be through the two-component system (arlS/silS-arlR) and beta-lactam resistance system (mexI-mexV-oprM/oprZ/smeF). Overall, this study provides new insights into the effects of Ag0-NPs at environmental concentrations on the ecological environment, especially regarding the mechanism of regulating ARGs in estuarine biofilms.

中文翻译：

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银纳米颗粒通过改变细菌群落并在河口生物膜中产生抗银基因来调节抗生素耐药基因


生物膜被认为是抗生素耐药基因 （ARG） 和纳米颗粒 （NP） 的汇，然而，关于生物膜中 NPs 和 ARGs 之间相互作用的研究是有限的。本研究重点研究了长江口环境浓度为 10 μg/L 的零价银纳米颗粒 （Ag0-NPs） 和 Ag 离子连续处理后，ARGs 形成生物膜过程中的发生和调控机制。生物被膜可富集大量 Ag，Ag0-NPs 和 Ag 离子组在 28 d 时最高浓度为 97.60 mg/kg 和 111.08 mg/kg。与 28 天时的空白相比，Ag0-NPs 组的 ARGs 丰度降低了 2.2 倍，而 Ag 离子组增加了 1.3 倍。Ag0-NPs 和 Ag 离子诱导生物膜中银抗性基因 （SRG） 或带有 SRG 的选定细菌的产生。基于机器学习，细菌群落、SRGs 和 Ag 浓度是 ARGs 的前 3 大优势调节因子，贡献率分别为 27.74 % 、 25.57 % 和 17.93 %。结构方程模型显示，Ag 可以通过调节 Ag0-NPs 组的细菌群落间接调节 ARGs。宏基因组测序进一步显示，Ag0-NPs 组中大多数降低的 ARGs 由 Betaproteobacteria 承载。根据 KEGG 通路数据库，Ag0-NPs/Ag 离子调控 ARGs 的可能分子机制可能是通过双组分系统 （arlS/silS-arlR） 和 β-内酰胺抗性系统 （mexI-mexV-oprM/oprZ/smeF）。总的来说，本研究为环境浓度下 Ag0-NPs 对生态环境的影响提供了新的见解，特别是关于调节河口生物膜中 ARGs 的机制。