Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Hangzhou water Group Company LTD, China.
J Hazard Mater. 2021 Mar 15;406:124335. doi: 10.1016/j.jhazmat.2020.124335. Epub 2020 Oct 20.
Viable but non-culturable (VBNC) bacteria have attracted widespread attention since they are inherently undetected by traditional culture-dependent methods. Importantly, VBNC bacteria could resuscitate under favorable conditions leading to significant public health concerns. Although the total number of viable bacteria has been theorized to be far greater than those that can be cultured, there have been no reports quantifying VBNC pathogenic bacteria in full-scale drinking water treatment plants (DWTPs). In this work, we used both culture-dependent and quantitative PCR combination with propidium monoazide (PMA) dye approaches to characterize cellular viability. Further, we established a method to quantify viable pathogens by relating specific gene copies to viable cell numbers. Ratios of culturable bacteria to viable 16S rRNA gene copies in water and biological activated carbon (BAC) biofilms were 0-4.75% and 0.04-56.24%, respectively. The VBNC E. coli, E. faecalis, P. aeruginosa, Salmonella sp., and Shigella sp. were detected at levels of 0-10 cells/100 mL in source water, 0-10 cells/100 mL in chlorinated water, and 0-10 cells/g in BAC biofilms. In addition, differences between the total and viable community structures after ozonation and chlorination were investigated. The relative abundance of opportunistic pathogens such as Mycobacterium, Sphingomonas, etc. increased in final water, likely due to their chlorine resistance. In summary, we detected significant quantities of viable/VBNC opportunistic pathogens in full-scale DWTPs, confirming that traditional, culture-dependent methods are inadequate for detecting VBNC bacteria. These findings suggest a need to develop and implement rapid, accurate methods for the detection of VBNC pathogenic bacteria in DWTPs to ensure the safety of drinking water.
存活但不可培养（VBNC）细菌因其无法被传统的依赖培养的方法检测到而受到广泛关注。重要的是，VBNC 细菌在有利条件下可以复苏，这引起了重大的公共卫生关注。尽管理论上存活细菌的总数远远大于可培养的细菌数量，但目前还没有报道定量检测全规模饮用水处理厂（DWTP）中 VBNC 致病性细菌的数量。在这项工作中，我们使用了依赖培养和定量 PCR 结合吖啶橙（PMA）染料的方法来表征细胞活力。此外，我们建立了一种通过将特定基因拷贝与活细胞数量相关联来定量检测活病原体的方法。水中和生物活性炭（BAC）生物膜中可培养细菌与活 16S rRNA 基因拷贝的比例分别为 0-4.75%和 0.04-56.24%。在原水中可检测到 VBNC 大肠杆菌、粪肠球菌、铜绿假单胞菌、沙门氏菌和志贺氏菌，浓度为 0-10 个细胞/100mL，氯化水中为 0-10 个细胞/100mL，BAC 生物膜中为 0-10 个细胞/g。此外，还研究了臭氧和氯化处理后总群落结构和活群落结构之间的差异。在最终水中，机会性病原体（如分枝杆菌、鞘氨醇单胞菌等）的相对丰度增加，可能是由于其对氯的抵抗力。总之，我们在全规模 DWTP 中检测到大量存活/VBNC 机会性病原体，证实传统的依赖培养的方法不足以检测 VBNC 细菌。这些发现表明，需要开发和实施快速、准确的方法来检测 DWTP 中的 VBNC 致病性细菌，以确保饮用水的安全。
