摘要
抽象图像
废水是水生环境中细胞外抗生素抗性基因（eArGs）的主要来源，对人类健康和生物安全构成威胁。然而，人们对废水中的有机物（EfOM）可能在多大程度上促进eArGs的光敏氧化知之甚少。发现EfOM的三重态在eArGs的降解中占主导地位（占85%）。光氧化主要通过质子耦合电子转移反应进行。它们破坏了质粒链并破坏了碱基。O2•–也参与其中，并与反应的eArGs中间自由基偶联。blaTEM-1和tet-A链段（209–216 bps）与4-羧基二苯甲酮的三重态的二阶反应速率计算为（2.61–2.75）×108 M–1 s–1。除了作为光敏剂外，EfOM中的抗氧化部分还充当猝灭剂，将中间自由基恢复到其原始形式，降低光降解速率。然而，陆地来源的天然有机物不能光敏，因为它形成的三重态较少，尤其是高能三重态，因此其抑制作用占主导地位。这项研究加深了我们对EfOM在eArGs光氧化中的作用以及EfOM与陆地来源的天然有机物之间的差异的理解。
Abstract
Abstract Image
Wastewater effluent is a major source of extracellular antibiotic resistance genes (eArGs) in the aquatic environment, a threat to human health and biosecurity. However, little is known about the extent to which organic matter in the wastewater effluent (EfOM) might contribute to photosensitized oxidation of eArGs. Triplet states of EfOM were found to dominate the degradation of eArGs (accounting for up to 85%). Photo-oxidation proceeded mainly via proton-coupled electron transfer reactions. They broke plasmid strands and damaged bases. O2•– was also involved, and it coupled with the reactions’ intermediate radicals of eArGs. The second-order reaction rates of blaTEM-1 and tet-A segments (209–216 bps) with the triplet state of 4-carboxybenzophenone were calculated to be (2.61–2.75) × 108 M–1 s–1. Besides as photosensitizers, the antioxidant moieties in EfOM also acted as quenchers to revert intermediate radicals back to their original forms, reducing the rate of photodegradation. However, the terrestrial origin natural organic matter was unable to photosensitize because it formed less triplets, especially high-energy triplets, so its inhibitory effects predominated. This study advances our understanding of the role of EfOM in the photo-oxidation of eArGs and the difference between EfOM and terrestrial-origin natural organic matter.

https://pubs.acs.org/doi/abs/10.1021/acs.est.2c08036