The spread of antibiotic resistance genes (ARGs) has become a global environmental issue; it has been found that nanoparticles (NPs) can promote the transfer of ARGs between bacteria. However, it remains unclear whether NPs can affect this kind of conjugation in Streptomyces, which mainly conjugate with other bacteria via spores. In the present study, we demonstrated that Al2O3 NPs significantly promote the conjugative transfer of ARGs from Escherichia coli (E. coli) ET12567 to Streptomyces coelicolor (S. coelicolor) M145 without the use of heat shock method. The number of transconjugants induced by Al2O3 particles was associated with the size and concentration of Al2O3 particles, exposure time, and the ratio of E. coli and spores. When nanoparticle size was 30 nm at a concentration of 10 mg/L, the conjugation efficiency reached a peak value of 182 cfu/108 spores, which was more than 60-fold higher than that of the control. Compared with nanomaterials, bulk particles exhibited no significant effect on conjugation efficiency. We also explored the mechanisms by which NPs promote conjugative transfer. After the addition of NPs, the intracellular ROS content increased and the expression of the classical porin gene ompC was stimulated. In addition, ROS enhanced the mRNA expression levels of conjugative genes by inhibiting global regulation genes. Meanwhile, expression of the conjugation-related gene intA was also stimulated, ultimately increasing the number of transconjugants. Our results indicated that Al2O3 NPs significantly promoted the conjugative transfer of ARGs from bacteria to spores and aggravated the diffusion of resistance genes in the environment.

中文翻译：

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暴露于Al2O3纳米颗粒可促进抗生素抗性基因从大肠杆菌到链霉菌的共轭转移。

抗生素抗性基因（ARGs）的传播已成为全球性的环境问题。已经发现，纳米颗粒（NP）可以促进ARG在细菌之间的转移。然而，目前尚不清楚NPs是否会影响链霉菌中的这种结合，这种结合主要通过孢子与其他细菌结合。在本研究中，我们证明了Al2O3 NPs可以显着促进ARGs从大肠杆菌（E. coli）ET12567到共生色链霉菌（S. coelicolor）M145的共轭转移，而无需使用热激方法。Al2O3颗粒诱导的共轭结合物的数量与Al2O3颗粒的大小和浓度，暴露时间以及大肠杆菌和孢子的比例有关。当10 mg / L的纳米颗粒尺寸为30 nm时，结合效率达到了峰值182 cfu / 108孢子，比对照高60倍以上。与纳米材料相比，散装颗粒对缀合效率没有显着影响。我们还探讨了NP促进共轭转移的机制。加入NP后，细胞内ROS含量增加，经典孔蛋白基因ompC的表达受到刺激。此外，ROS通过抑制全局调控基因提高了共轭基因的mRNA表达水平。同时，也刺激了缀合相关基因intA的表达，最终增加了转缀合剂的数量。