摘要

       抗生素耐药基因（ARGs）的传播对公众健康和食品安全构成了全球性的威胁。然而，ARG在农业土壤中通过质粒动员（一种广泛的寄主范围转移系统）传播的研究却很少。在不同的条件下，包括不同的养分浓度、温度、土壤深度、根际土壤和土壤类型，通过动员pSUP106，研究了氯霉素抗性基因（CRG）和四环素抗性基因（TRG）在农业土壤中的传播。根据试验条件，在未灭菌土壤中，每克土壤中分离到的抗性细菌约为104~107株，隶属于4属5~10种，包括非致病菌、条件致病菌、致病菌、革兰氏阳性菌和革兰氏阴性菌。在无菌土壤中，较高的营养水平和较高的温度促进了质粒的动员和ARG的表达。表层和深层土壤可能不支持抗生素抗性的传播，而玉米根际和壤土对质粒动员的ARG传播有较好的支持作用。这些因素都可能改变细菌的生长和活性，从而导致上述影响。只有供体和辅助体的引入，或仅供体的引入，也导致了ARGs和大量耐药菌（ARB）的转移，表明一些本土细菌含有质粒动员所必需的元素。结果表明，质粒动员促进了ARGs和ARB在土壤中的传播，导致了本地细菌群落的干扰。明确ARG的传播途径，抑制ARGs的传播具有重要意义。

Spread of antibiotic resistance genes (ARGs) poses a worldwide threat to public health and food safety. However, ARG spread by plasmid mobilization, a broad host range transfer system, in agricultural soil has received little attention. Here, we investigated the spread of chloramphenicol resistance gene (CRG) and tetracycline resistance gene (TRG) in agricultural soil by mobilization of pSUP106 under different conditions, including different concentrations of nutrients, temperatures, soil depths, rhizosphere soils, and soil types. The number of resistant bacteria isolated in non-sterilized soil from the experiments was approximately 10⁴ to 10⁷ per gram of soil, belonging to 5-10 species from four genera, including nonpathogen, opportunistic pathogen, pathogen bacteria, and gram-positive and gram-negative bacteria, depending on the experiment conditions. In sterilized soil, higher levels of nutrients and higher temperatures promoted plasmid mobilization and ARG expression. Topsoil and deep soil might not support the spread of antibiotic resistance, while ARG dissemination by plasmid mobilization was better supported by maize rhizosphere and loam soils. All these factors might change bacterial growth and the activity of bacteria and lead to the above influence. Introduction of only the donor and helper, or the donor alone also resulted in the transfer of ARGs and large numbers of antibiotic resistant bacteria (ARB), indicating that some indigenous bacteria contain the elements necessary for plasmid mobilization. Our results showed that plasmid mobilization facilitated dissemination of ARGs and ARB in soil, which led to the disturbance of indigenous bacterial communities. It is important to clear ARG dissemination routes and inhibit the spread of ARGs.

        https://www.sciencedirect.com/science/article/pii/S0269749119356350?via%3Dihub