摘要

      由于严重的公共健康风险，人们对水生环境中抗药性细菌（ARB）数量的增加和抗药性基因（ARGs）的传播产生了浓厚的科学兴趣。本研究以大肠杆菌DH5α（CTX）、大肠杆菌DH5α（mcr）和链霉素耐药受体菌株（E.coli C600（Sm））为研究对象，研究了两种抗生素耐药供体菌株对头孢菌素（blaCTX）和多粘菌素（mcr-1）耐药基因的结合转移，以明确ARG转移的机制。研究了在可见光（VL）、模拟太阳光（SS）和紫外光（UV254nm）等不同光照条件下的共轭转移。结果表明，VL辐射对共轭转移频率没有影响，SS辐射对共轭转移频率的影响较小（2-10倍），UV辐射对共轭转移频率的影响最大（100倍）。此外，本研究还探讨了ARG转移与胁迫条件之间的关系。通过研究共培养AR-E.coli菌株在应激条件下的生理生化变化、氧化应激反应和功能基因表达。当与转移频率结果相关时，我们发现VL辐射没有影响细菌的生理生化特性，也没有诱导氧化应激和基因表达。SS照射时，氧化应激发生缓慢，靶基因表达略有增加。与之相反，紫外线照射后，细菌迅速失活，氧化应激程度非常严重，靶基因表达明显上调。我们的研究可以提供新的线索，揭示加速接合转移和氧化应激之间的内在机制和联系，以及与接合和其他应激反应相关的基因在细菌细胞中的表达变化。

       Due to the significant public health risks, there is substantial scientific interest in the increasing abundance of antibiotic-resistance bacteria (ARB) and the spread of antibiotic-resistance genes (ARGs) in aquatic environments. To clearly understand the mechanism of ARG transfer, this study examined the conjugative transfer of genes encoding resistance to cephalosporin (bla_CTX) and polymyxin (mcr-1) from two antibiotic-resistant donor strains, namely E. coli DH5α (CTX) and E. coli DH5α (MCR), and to a streptomycin-resistant receptor strain (E. coli C600 (Sm)). Conjugative transfer was specifically studied under different light irradiation conditions including visible light (VL), simulated sunlight (SS) and ultraviolet light (UV_254nm). Results show that the conjugative transfer frequency was not affected by VL irradiation, while it was slightly improved (2-10 fold) by SS irradiation and extremely accelerated (up to 100 fold) by UV irradiation. Furthermore, this study also explored the link between ARG transfer and stress conditions. This was done by studying physiological and biochemical changes; oxidative stress response; and functional gene expression of co-cultured AR-E. coli strains under stress conditions. When correlated with the transfer frequency results, we found that VL irradiation did not affect the physiological and biochemical characteristics of the bacteria, or induce oxidative stress and gene expression. For SS irradiation, oxidative stress occurred slowly, with a slight increase in the expression of target genes in the bacterial cells. In contrast, UV irradiation, rapidly inactivated the bacteria, the degree of oxidative stress was very severe and the expression of the target genes was markedly up-regulated. Our study could provide new insight into the underlying mechanisms and links between accelerated conjugative transfer and oxidative stress, as well as the altered expression of genes relevant to conjugation and other stress responses in bacterial cells.

        https://www.sciencedirect.com/science/article/abs/pii/S0043135418309400?via%3Dihub