摘要

      在高浓度和亚抑制浓度的水环境中，抗生素有可能选择用于抗药性基因（ARGs）进化，对水环境生态安全构成潜在风险。我们对抗生素选择性压力下天然水体沉积物中ARGs和细菌群落的时间和连续动态的认识有限。本研究采用120-d操作流体力学介观研究了水-沉积物系统中ARGs的时间动态，以及14种常用抗生素衰减和迁移后的主要选择机制。在抗生素的选择性压力下，ARGs瞬时繁殖，抗生素去除后继续存在；细菌群落结构也发生了变化。Mantel试验和网络分析表明，ARGs与水体和表层沉积物中的细菌群落显著相关。结构方程模型（SEM）进一步揭示了ARGs的进化主要是由于细菌群落的变化和通过第1类整合子整合酶基因（intI1）的水平基因转移（HGT）的直接影响，而抗生素则间接影响了ARG的分布。ARGs在深层沉积物中的迁移与细菌群落和intI1无关，但可能与抗生素选择效应和ARG转化有关。

      Antibiotics in aquatic environments at high concentrations and sub-inhibitory concentrations potentially select for the evolution of antibiotic resistant genes (ARGs), posing a potential risk to aquatic ecological safety. Our knowledge of the temporal and successive dynamics of ARGs and bacterial community under the selective pressure of antibiotics in natural water-sediment system was limited. This study used a 120-d operating hydrodynamic mesocosm to explore the temporal dynamics of ARGs in water-sediment systems, and the main selective mechanisms following the attenuation and transport of 14 commonly used antibiotics. Under the selective pressures by antibiotics, ARGs propagated transiently, and persisted after antibiotic removal; the bacterial community structures likewise changed. Mantel test and network analysis indicated that ARGs significantly correlated with the bacterial community in the water and surface sediments. Structural equation model (SEM) further revealed that the evolution of ARGs was mainly due to the direct effect of the change in bacterial community and horizontal gene transfer (HGT) via the class 1 integron-integrase gene (intI1), but antibiotics indirectly influenced ARG profiles. The migration of ARGs in deep layer sediments was not related to the bacterial community and intI1, but may be explained by antibiotic selective effects and ARG transformation.

      https://linkinghub.elsevier.com/retrieve/pii/S0160-4120(19)34366-1