摘要

       抗生素抗性基因 (ARG) 的增殖和传播正在成为全球性危机。水生环境中编码 ARGs (eARGs) 的细胞外 DNA 在抗菌素耐药基因的分散中起着关键作用。为了生态安全和人类健康，迫切需要控制 eARG 传播的策略。为了实现这一目标，磁性生物炭/季鏻盐 (MBQ) 被用于研究 eARG 的效率和去除机制。与未修饰的相比，经季鏻盐修饰的磁性生物炭将细胞外 DNA 的吸附能力提高了约 9 倍。 MBQ对DNA的吸附在非均相系统中主要以化学吸附为主，在酸性和低盐环境中得到促进。 •OH和MBQ胶体的产生共同将DNA切割成片段，通过静电力以及DNA的构象转变促进DNA的磷酸骨架吸附到MBQ上。此外，在水中应用 MBQ 后细胞外 DNA 的定量表明，超过 92.7% 的耐药基因被去除，表明抗菌素耐药性在水生环境中传播的风险显着降低。这些发现对于应用 MBQ 减缓 ARGs 在水生环境中的传播具有实际意义。

       The proliferation and spread of antibiotic resistance genes (ARGs) is becoming a worldwide crisis. Extracellular DNA encoding ARGs (eARGs) in aquatic environment plays a critical role in the dispersion of antimicrobial resistance genes. Strategies to control the dissemination of eARGs are urgently required for ecological safety and human health. Towards this goal, magnetic biochar/quaternary phosphonium salt (MBQ), was used to investigate the efficiency and removal mechanism for eARGs. Magnetic biochar modified by quaternary phosphonium salt enhanced the adsorption capacity of extracellular DNA to approximately 9 folds, compared to that of the unmodified. DNA adsorption by MBQ was mainly dominated by chemisorption in heterogeneous systems and was promoted in acidic and low-salt environment. The generation of •OH and MBQ colloid jointly cleaved DNA into fragments, facilitating the adsorption of the phosphate backbone of DNA onto MBQ through electrostatic force as well as the conformational transition of DNA. Furthermore, quantification of extracellular DNA after MBQ was applied in water demonstrated that over 92.7% of resistance genes were removed, indicating a significantly reduced risk of propagation of antimicrobial resistance in aquatic environments. These findings have a practical significance in the application of MBQ in mitigating the spread of ARGs in aquatic environment.

https://www.sciencedirect.com/science/article/pii/S0304389421000121