Department of Environmental Engineering, Graduate School of Engineering, Kyoto University, Kyoto University Katsura, Nishikyo, Kyoto 615-8540, Japan.
Department of Environmental Engineering, Graduate School of Engineering, Kyoto University, Kyoto University Katsura, Nishikyo, Kyoto 615-8540, Japan.
Sci Total Environ. 2024 Dec 15;956:177302. doi: 10.1016/j.scitotenv.2024.177302. Epub 2024 Nov 7.
This study investigated the occurrence of Legionella spp. in a chlorinated drinking water distribution system (DWDS), focusing on their community compositions and association with physicochemical water quality. Water samples were collected throughout the DWDS, covering from the treated water reservoir to distal ends. Although Legionella spp. genes were not detected at the reservoir, their abundance dramatically increased along the distribution network, reaching up to 4.4 log copies/L at distal sites. The Legionella communities were further characterized by high-throughput amplicon sequencing targeting the genus-specific 16S rRNA gene. The results revealed a diverse Legionella community, including amplicon sequence variants with high similarity (> 99 %) to potentially pathogenic species such as L. drozanskii and L. pneumophila, albeit at low levels. Moreover, Legionella community diversity increased significantly along the distribution system, leading to distinct community compositions at distal sites. Importantly, decay of residual chlorine concentration was identified as a key factor both in increasing the Legionella gene levels and shaping the community structure. Overall, this study underscores the importance of preventing pipe corrosion and maintaining adequate disinfectant residuals to minimize Legionella regrowth in DWDS.
本研究调查了氯化饮用水分配系统（DWDS）中军团菌属的发生情况，重点关注其群落组成及其与理化水质的关系。水样取自 DWDS 各处，从处理水水库到末端。尽管在水库中未检测到军团菌属基因，但它们的丰度沿管网显著增加，在末端处达到 4.4 对数拷贝/升。通过靶向属特异性 16S rRNA 基因的高通量扩增子测序进一步表征了军团菌群落。结果显示，军团菌群落多样，包括与潜在致病种（如 L. drozanskii 和 L. pneumophila）具有高相似性（>99%）的扩增子序列变异体，但其水平较低。此外，军团菌群落多样性沿管网显著增加，导致末端处的群落组成明显不同。重要的是，余氯浓度的衰减被确定为增加军团菌基因水平和塑造群落结构的关键因素。总的来说，本研究强调了防止管道腐蚀和保持足够消毒剂残留的重要性，以最大限度地减少 DWDS 中军团菌的再生。
