摘要

由于显着的公共卫生风险，对抗生素抗性细菌（ARB）的丰度增加和抗生素抗性基因（ARG）在水生环境中的传播具有重要的科学意义。为了清楚地了解ARG转移的机制，本研究检测了两种抗生素抗性供体菌株即大肠杆菌DH5α（CTX）和E的编码对头孢菌素（blaCTX）和多粘菌素（mcr-1）抗性的基因的接合转移。大肠杆菌DH5α（MCR）和链霉素抗性受体菌株（大肠杆菌C600（Sm））。在包括可见光（VL），模拟太阳光（SS）和紫外光（UV254nm）的不同光照条件下具体研究了共轭转移。结果表明，接合转移频率不受VL照射的影响，而通过SS照射稍微改善（2-10倍）并且通过UV照射极大加速（高达100倍）。此外，本研究还探讨了ARG转移与压力条件之间的联系。这是通过研究生理和生化变化来完成的;氧化应激反应;和共培养的AR-E的功能基因表达。应激条件下的大肠杆菌菌株当与转移频率结果相关时，我们发现VL辐射不影响细菌的生理生化特征，或诱导氧化应激和基因表达。对于SS照射，氧化应激缓慢发生，细菌细胞中靶基因的表达略微增加。相反，紫外线照射使细菌迅速失活，氧化应激程度非常严重，靶基因的表达显着上调。我们的研究可以提供对加速接合转移和氧化应激之间的潜在机制和联系的新见解，以及与细菌细胞中的缀合和其他应激反应相关的基因表达的改变。

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 (blaCTX) 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 (UV254nm). 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.ncbi.nlm.nih.gov/pubmed/30465986