摘要
抽象图像
抗生素抗性基因（ARGs）通过自然转化的传播是由稳定细胞外DNA（eDNA）和诱导活性氧（ROS）的因素促进的，活性氧使受体细胞渗透并上调转化能力基因。在这项研究中，我们证明耐辐射球菌可以通过去除使受体细胞更容易转化的eDNA和ROS来缓解ARG的传播途径。我们使用质粒RP4作为细胞外ARGs（tetA、aphA和blaTEM-2）的来源，并使用机会性病原体粪肠球菌作为受体。耐辐射D.radiodurans的存在显著降低了转化频率，从2.5±0.7×10–6降至7.4±1.4×10–7（p<0.05）。基于细胞内ROS积累和超氧化物歧化酶（SOD）活性的定量、定量聚合酶链式反应（qPCR）和转录组分析，我们提出了耐辐射D.radiodurans通过ARGs缓解粪大肠杆菌转化的两种机制：（a）残留抗生素诱导耐辐射D.adiodurans合成脂溶性类胡萝卜素，清除ROS，从而减轻粪大肠杆菌对eDNA摄取的敏感性；（b）eDNA诱导耐辐射D.radioduranns合成降解eARGs的细胞外核酸酶。这种机制性的见解为生物策略（包括生物强化）提供了信息，以通过转化来减少ARGs的传播。
Abstract
Abstract Image
Dissemination of antibiotic resistance genes (ARGs) through natural transformation is facilitated by factors that stabilize extracellular DNA (eDNA) and that induce reactive oxygen species (ROS) that permeabilize receptor cells and upregulate transformation competence genes. In this study, we demonstrate that Deinococcus radiodurans can mitigate this ARG dissemination pathway by removing both eDNA and ROS that make recipient cells more vulnerable to transformation. We used plasmid RP4 as source of extracellular ARGs (tetA, aphA, and blaTEM-2) and the opportunistic pathogen Enterococcus faecalis as receptor. The presence of D. radiodurans significantly reduced the transformation frequency from 2.5 ± 0.7 × 10–6 to 7.4 ± 1.4 × 10–7 (p < 0.05). Based on quantification of intracellular ROS accumulation and superoxide dismutase (SOD) activity, and quantitative polymerase chain reaction (qPCR) and transcriptomic analyses, we propose two mechanisms by which D. radiodurans mitigates E. faecalis transformation by ARGs: (a) residual antibiotics induce D. radiodurans to synthesize liposoluble carotenoids that scavenge ROS and thus mitigate the susceptibility of E. faecalis for eDNA uptake, and (b) eDNA induces D. radiodurans to synthesize extracellular nucleases that degrade eARGs. This mechanistic insight informs biological strategies (including bioaugmentation) to curtail the spread of ARGs through transformation.

https://pubs.acs.org/doi/abs/10.1021/acs.est.2c03919