Zhu Lin, Shuai Xinyi, Xu Like, Sun Yujie, Lin Zejun, Zhou Zhenchao, Meng Lingxuan, Chen Hong
Department of Environmental Engineering, College of Environmental and Resource Sciences; Zhejiang University, Hangzhou 310058, China.
Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK.
J Hazard Mater. 2022 Feb 5;423(Pt B):127228. doi: 10.1016/j.jhazmat.2021.127228. Epub 2021 Sep 14.
The occurrence of viable but non-culturable (VBNC) bacteria in the wastewater system poses a huge threat to environmental and public health, in particular in hospital wastewater treatment system (HWTS). HWTS-oriented studies have been conducted to assess the effectiveness of chlorination and UV disinfection using indigenous bacteria. Results revealed that the VBNC Escherichia coli and ARGs remained persistent even at high chlorination (12 mg/L for 2.5 h) and UV doses (1000 mJ/cm). The molecular mechanisms underlying chlorination-/UV-induced VBNC state in E. coli were explored through the transcriptomics and results suggested that most energy-dependent physiological activities (e.g., metabolism) have been suppressed in VBNC E. coli, while the pathogenicity-related genes varied insignificantly compared to the culturable cells, indicating that the VBNC E. coli could potentially display pathogenicity. Further Galleria mellonella model experiment has confirmed that although the disinfection-induced VBNC state made cells less infectious, these cells could regain their pathogenicity after resuscitation. This in vitro study can be used as a reference for studies on infections from VBNC bacteria and highlights the health risk due to VBNC pathogens in hospital effluents. There is a need to develop effluent standards specifically for healthcare facilities, and a stricter downstream disinfection strategy should be considered for the removal of VBNC cells and ARGs in the effluent.
废水系统中活的但不可培养（VBNC）细菌的出现对环境和公众健康构成了巨大威胁，尤其是在医院污水处理系统（HWTS）中。已经开展了以HWTS为导向的研究，以评估使用本地细菌进行氯化消毒和紫外线消毒的效果。结果显示，即使在高氯化剂量（12毫克/升，持续2.5小时）和高紫外线剂量（1000毫焦/平方厘米）下，VBNC大肠杆菌和抗生素抗性基因（ARGs）仍具有持久性。通过转录组学探究了氯化/紫外线诱导大肠杆菌进入VBNC状态的分子机制，结果表明，VBNC大肠杆菌中大多数依赖能量的生理活动（如新陈代谢）受到抑制，而与致病性相关的基因与可培养细胞相比变化不显著，这表明VBNC大肠杆菌可能仍具有致病性。进一步的大蜡螟模型实验证实，尽管消毒诱导的VBNC状态使细胞的传染性降低，但这些细胞复苏后仍可恢复其致病性。这项体外研究可为VBNC细菌感染的研究提供参考，并突出了医院废水中VBNC病原体带来的健康风险。有必要制定专门针对医疗机构的废水排放标准，并且应考虑采用更严格的下游消毒策略来去除废水中的VBNC细胞和ARGs。
