Wang Qi, Li Xiao, Zhou Keying, Li Yutong, Wang Yanjie, Zhang Guodong, Guo He, Zhou Jian, Wang Tiecheng
College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi Province 712100, PR China; Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, Yangling, Shaanxi 712100, PR China.
College of Chemistry & Pharmacy, Northwest A&F University, Yangling, Shaanxi Province 712100, PR China.
J Hazard Mater. 2024 Sep 5;476:135181. doi: 10.1016/j.jhazmat.2024.135181. Epub 2024 Jul 11.
Dissemination of antibiotic resistance genes (ARGs) has become a critical threat to public health. Activated sludge, rich in extracellular polymeric substances (EPS), is an important pool of ARGs. In this study, mechanisms of conjugation transfer of ARGs induced by EPS, including tightly bound EPS (TBEPS), soluble EPS (SEPS), and loosely bound EPS (LBEPS), were explored in terms of molecular diversities and electron transfer properties of EPS. Conjugation transfer frequency was increased by 9.98-folds (SEPS), 4.21-folds (LBEPS), and 15.75-folds (TBEPS) versus the control, respectively. Conjugation-related core genes involving SOS responses (9 genes), membrane permeability (18 genes), intercellular contact (17 genes), and energy metabolism pathways (13 genes) were all upregulated, especially in the presence of TBEPS. Carbohydrates and aliphatic substances in SEPS and LBEPS were contributors to ARG transfer, via influencing reactive oxygen species (ROS) formation (SEPS) and ROS and adenosine triphosphate (ATP) production (LBEPS). TBEPS had the highest redox potential and greatest lability and facilitated electron transfer and alternated respiration between cells, thus promoting ARG transfer by producing ATP. Generally, the chemical molecular characteristics and redox properties of EPS facilitated ARG transfer mainly by influencing lipid peroxidation and ATP, respectively.
抗生素抗性基因（ARGs）的传播已成为对公众健康的重大威胁。富含胞外聚合物（EPS）的活性污泥是ARGs的一个重要储存库。在本研究中，从EPS的分子多样性和电子转移特性方面，探讨了由紧密结合EPS（TBEPS）、可溶性EPS（SEPS）和松散结合EPS（LBEPS）诱导的ARGs接合转移机制。与对照相比，接合转移频率分别提高了9.98倍（SEPS）、4.21倍（LBEPS）和15.75倍（TBEPS）。涉及SOS反应（9个基因）、膜通透性（18个基因）、细胞间接触（17个基因）和能量代谢途径（13个基因）的接合相关核心基因均上调，尤其是在TBEPS存在的情况下。SEPS和LBEPS中的碳水化合物和脂肪族物质通过影响活性氧（ROS）形成（SEPS）以及ROS和三磷酸腺苷（ATP）产生（LBEPS），促进了ARG转移。TBEPS具有最高的氧化还原电位和最大的反应活性，促进了细胞间的电子转移和交替呼吸，从而通过产生ATP促进ARG转移。总体而言，EPS的化学分子特征和氧化还原特性分别主要通过影响脂质过氧化和ATP来促进ARG转移。
