摘要

      由于抗生素和金属抗性的相似机制，人们越来越担心金属污染可能会选择环境中的抗生素抗性基因 (ARG)。在这里，我们构建了短期实验室缩影，以研究用 Cu 浓度梯度 (0~1000 mg kg-1) 修正的农业土壤中各种 ARG 和两种铜 (Cu) 抗性基因的动态。移动遗传元件 (MGE) 也被量化为 ARG 水平基因转移潜力的代表。我们使用高容量定量 PCR 阵列在所有土壤样品中检测到 126 个独特的 ARG，多药和 β-内酰胺抗性是最丰富的 ARG 类别。铜添加物显着提高了 ARGs 和 MGEs 的绝对和相对丰度，它们沿着 Cu 浓度的梯度逐渐增加。两种铜抗性基因（copA 和 pcoR）在低水平铜处理（50 和 100 mg kg-1）中高度富集，并且它们的丰度随着铜浓度的增加而减少。在所有经 Cu 改良的处理中，金属和抗生素抗性水平随着时间的推移逐渐下降，但在 56 天的培养后，受污染土壤中的金属和抗生素抗性水平仍显着高于未处理土壤。网络分析揭示了 ARGs 和 MGEs 之间的显着关联，表明抗生素抗性在 Cu 改良土壤中的迁移潜力。在ARGs和铜抗性基因之间没有发现显着的正相关，表明这些基因不在同一细菌宿主中。总之，我们的结果提供了经验证据，表明短期铜胁迫会导致高水平抗生素和金属抗性的演变，并显着改变土壤 ARG 的多样性、丰度和水平转移潜力。

      Owing to the similar mechanisms of antibiotic and metal resistance, there is a growing concern that metal contamination may select for antibiotic resistance genes (ARGs) in the environment. Here, we constructed short-term laboratory microcosms to investigate the dynamics of a wide range of ARGs and two copper (Cu) resistance genes in an agricultural soil amended with a gradient of Cu concentrations (0~1000 mg kg−1). Mobile genetic elements (MGEs) were also quantified as a proxy for the horizontal gene transfer potential of ARGs. We detected 126 unique ARGs across all the soil samples using the high-capacity quantitative PCR array, and multidrug and β-lactam resistance were the most abundant ARG categories. The copper amendments significantly enhanced the absolute and relative abundances of ARGs and MGEs, which gradually increased along the gradient of increasing Cu concentrations. The two Cu resistance genes (copA and pcoR) were highly enriched in low-level Cu treatment (50 and 100 mg kg−1), and their abundances decreased with the increasing Cu concentrations. The level of metal and antibiotic resistance gradually declined over time in all Cu-amended treatments but was still considerably higher in contaminated soils than untreated soils after 56 days’ incubation. Significant associations among ARGs and MGEs were revealed by the network analysis, suggesting the mobility potential of antibiotic resistance in Cu-amended soils. No significant positive correlations were found between ARGs and copper resistance genes, suggesting that these genes are not located in the same bacterial hosts. Taken together, our results provide empirical evidence that short-term copper stress can cause evolution of high-level antibiotic and metal resistance and significantly change the diversity, abundance, and horizontal transfer potential of soil ARGs.

https://link.springer.com/article/10.1007/s11356-018-2978-y