摘要
      土壤是抗生素抗性细菌和抗生素抗性基因（ARGs）的主要天然宿主。它们的传播和增殖在很大程度上是由结合转移引起的，而土壤成分对细菌结合转移的影响及其潜在机制仍知之甚少。在本研究中，两株大肠杆菌分别暴露于土壤矿物（石英、高岭石和蒙脱石）和有机物（腐殖酸、生物炭和煤烟）中，以研究它们对ARGs结合的影响。结果表明，石英对共轭没有显著影响；蒙脱石促进供体的生长，但抑制受体和偶联物的生长；高岭石和三种有机物显著促进了偶联剂的产生，而生物炭随着时间的延长先促进后抑制。在本研究涉及的细菌浓度范围内，偶联物的浓度随着供体和受体的浓度比（RD/R）的增加而增加，这表明偶联物产生的变化主要是通过改变RD/R来介导的。对生物炭处理组的进一步观察表明，细菌的反应，如细胞膜通透性、细胞表面疏水性和生物膜形成能力，随着暴露时间的推移而发生变化，这可能是影响偶联转移的潜在因素。总之，我们的研究结果表明，土壤成分的类型和暴露时间共同影响结合，而RD/R的变化和相关细菌反应是主要的潜在机制。
Abstract
Soil is the main natural reservoir of antibiotic resistant bacteria and antibiotic resistance genes (ARGs). Their dissemination and proliferation were largely motivated by conjugative transfer, while the influence of soil components on bacterial conjugative transfer and the underlying mechanisms remain poorly understood. In the present study, two Escherichia coli strains were exposed to soil minerals (quartz, kaolinite and montmorillonite) and organic matters (humic acid, biochar and soot) respectively to investigate their impact on ARGs conjugation. The results showed that quartz had no significant effect on conjugation; montmorillonite promoted the growth of the donor, but inhibited the recipient and conjugant; kaolinite and three organic matters significantly promoted the production of conjugant, while biochar promoted and then inhibited it with time prolong. Within the range of bacterial concentration involved in this study, the concentration of conjugant increased with the ratio of the concentration of donor and recipient (RD/R), indicating that the variation of conjugant production was mainly mediated by changing RD/R. Further observation of biochar treatment group showed that the bacterial responses such as cell membrane permeability, cell surface hydrophobicity and biofilm formation ability shifted with the exposure time, which might be a potential factor affecting conjugative transfer. Collectively, our findings suggest that the type and exposure time of soil components jointly affected conjugation, while the change of RD/R and related bacterial responses are the main underlying mechanisms.

https://www.sciencedirect.com/science/article/abs/pii/S004896972208336X