Chlorine disinfection to drinking water plays an important role in preventing and controlling waterborne disease outbreaks globally. Nevertheless, little is known about why it enriches the antibiotic resistance genes (ARGs) in bacteria after chlorination. Here, ARGs released from killed antibiotic-resistant bacteria (ARB), and culturable chlorine-injured bacteria produced in the chlorination process as the recipient, were investigated to determine their contribution to the horizontal transfer of ARGs during disinfection treatment. We discovered Escherichia coli, Salmonella aberdeen, Pseudomonas aeruginosa and Enterococcus faecalis showed diverse resistance to sodium hypochlorite, and transferable RP4 could be released from killed sensitive donor consistently. Meanwhile, the survival of chlorine-tolerant injured bacteria with enhanced cell membrane permeabilisation and a strong oxidative stress-response demonstrated that a physiologically competent cell could be transferred by RP4 with an improved transformation frequency of up to 550 times compared with the corresponding untreated bacteria. Furthermore, the water quality factors involving chemical oxygen demand (CODMn), ammonium nitrogen and metal ions (Ca2+ and K+) could significantly promote above transformation frequency of released RP4 into injured E. faecalis. Our findings demonstrated that the chlorination process promoted the horizontal transfer of plasmids by natural transformation, which resulted in the exchange of ARGs across bacterial genera and the emergence of new ARB, as well as the transfer of chlorine-injured opportunistic pathogen from non-ARB to ARB. Considering that the transfer elements were quite resistant to degradation through disinfection, this situation poses a potential risk to public health.

中文翻译：

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氯消毒通过自然转化促进细菌属之间抗生素抗性基因的交换。

饮用水氯消毒在全球预防和控制水传播疾病爆发中发挥着重要作用。然而，人们对氯化处理后为什么会富集细菌中抗生素抗性基因（ARG）的原因知之甚少。在这里，研究了从杀死的抗生素抗性细菌（ARB）中释放的ARG，以及作为受体的氯化过程中产生的可培养的氯损伤细菌，以确定它们对消毒处理期间ARG水平转移的贡献。我们发现大肠杆菌、阿伯丁沙门氏菌、铜绿假单胞菌和粪肠球菌对次氯酸钠表现出不同的耐药性，并且可转移的RP4可以从被杀死的敏感供体中持续释放。同时，具有增强的细胞膜通透性和强氧化应激反应的耐氯损伤细菌的存活表明，与相应的未处理细菌相比，RP4可以转移生理感受态细胞，其转化频率提高高达550倍。此外，化学需氧量（CODMn）、铵态氮和金属离子（Ca2+和K+）等水质因素可显着促进释放的RP4向受伤粪肠球菌的上述转化频率。我们的研究结果表明，氯化过程促进了质粒通过自然转化的水平转移，导致ARG在细菌属之间的交换和新ARB的出现，以及氯损伤的机会性病原体从非ARB转移到细菌属。 ARB。考虑到转移元件对消毒降解具有很强的抵抗力，这种情况对公众健康构成潜在风险。