摘要

       城市污水污泥的土地应用可能会带来将抗生素抗性基因 (ARG) 从城市环境引入农业系统的风险。然而，污水污泥回收和应用方法如何影响土壤抗性和移动遗传元件（MGEs）仍不清楚。在本研究中，对过去（1994 年至 1997 年）和每年（自 1994 年以来）应用五种不同污水污泥的田间试验中土壤的抗性组进行了高通量定量 PCR。两种污泥施用模式之间有机碳的总输入量相似。土壤内在抗性组，定义为对照和污泥修正地块中土壤共享的 ARG，由赋予对多药、β-内酰胺、大环内酯-林可酰胺-链霉素 B (MLSB)、四环素、万古霉素和氨基糖苷类抗性的基因组成，以多药耐药基因为最丰富的成员。土壤中ARGs的丰度与MGE标记基因之间存在很强的相关性。五种污泥中 ARGs 的组成和多样性与土壤中的 ARGs 有很大不同。污泥中相当比例的 ARGs 和 MGE 标记基因在应用后减弱，特别是氨基糖苷类和四环素抗性基因。通过持续引入和刺激土壤内在 ARG，年度应用对土壤抗性组产生更显着的影响。此外，观察到污泥特异性 ARG 直接引入土壤，尤其是富含 ARG 的污泥。这些结果提供了更好地了解 ARG 通过污水污泥应用从城市环境到农业系统的传播特征。

       Land applications of municipal sewage sludge may pose a risk of introducing antibiotic resistance genes (ARGs) from urban environments into agricultural systems. However, how the sewage sludge recycling and application method influence soil resistome and mobile genetic elements (MGEs) remains unclear. In the present study, high through-put quantitative PCR was conducted on the resistome of soils from a field experiment with past (between 1994 and 1997) and annual (since 1994) applications of five different sewage sludges. Total inputs of organic carbon were similar between the two modes of sludge applications. Intrinsic soil resistome, defined as the ARGs shared by the soils in the control and sludge-amended plots, consisted of genes conferring resistance to multidrug, β-lactam, Macrolide-Lincosamide-Streptogramin B (MLSB), tetracycline, vancomycin, and aminoglycoside, with multidrug resistance genes as the most abundant members. There was a strong correlation between the abundance of ARGs and MGE marker genes in soils. The composition and diversity of ARGs in the five sludges were substantially different from those in soils. Considerable proportions of ARGs and MGE marker genes in the sludges attenuated following the application, especially aminoglycoside and tetracycline resistance genes. Annual applications posed a more significant impact on the soil resistome, through both continued introduction and stimulation of the soil intrinsic ARGs. In addition, direct introduction of sludge-specific ARGs into soil was observed especially from ARG-rich sludge. These results provide a better insight into the characteristics of ARG dissemination from urban environment to the agricultural system through sewage sludge applications.

https://pubs.acs.org/doi/abs/10.1021/acs.est.6b02138