摘要

  开发了一个模型来解释抗生素抗性基因 (ARG) 作为细胞内 DNA (iDNA) 和细胞外 DNA (eDNA)，以预测 ARG 在污水处理厂 (WWTP) 下游接收水中的命运和运输。 eDNA 可以通过水平基因转移（即转化）促进 ARGs 的 iDNA 浓度；然而，之前的实地研究和预测模型并未涉及 eDNA 的流行及其影响。目前的模型跟踪水柱和沉积物中的 eDNA 和 iDNA，它包括物理、化学和生物过程。它还提供了一个框架，用于系统地确定对 eDNA 进行解释很重要的条件。例如，当转化时间尺度与平流时间尺度相比较小且 eDNA 的水柱浓度与 iDNA 相比较大时，忽略 eDNA 会显着低估 ARGs 的总量（例如，一个数量级或更多的）。该模型表明，污水处理厂排放中 ARG 的 eDNA 部分对于包含在预测中很重要，以改进水生环境中抗生素耐药性的风险评估

  A model is developed to account for antibiotic resistance genes (ARGs) as both intracellular DNA (iDNA) and extracellular DNA (eDNA) in predicting the fate and transport of ARGs in receiving waters downstream of wastewater treatment plants (WWTPs). eDNA can contribute to iDNA concentrations of ARGs through horizontal gene transfer (i.e., transformation); however, the prevalence of eDNA and its effects have not been addressed in previous field studies and predictive models. The present model tracks eDNA and iDNA in both the water column and the sediment, and it includes physical, chemical, and biological processes. It also provides a framework for systematically identifying conditions under which accounting for eDNA is important. For example, when the timescale for transformation is small compared with the timescale for advection and the water column concentration of eDNA is large compared with that of iDNA, ignoring eDNA can underpredict the total amount of ARGs significantly (e.g., by an order of magnitude or more). The model demonstrates that the eDNA fraction of ARGs in WWTP discharges is important to include in predictions for improved risk assessment of antibiotic resistance in the aquatic environment.

  https://www.liebertpub.com/doi/abs/10.1089/ees.2019.0319