Caution: The simultaneous invasion of trace metal pollutants in stagnant drinking water may lead to more serious microbial risks

The drinking water distribution system is the final line of defense to ensure water safety for people, however, some hidden risks may exist. Stagnation and the intrusion of trace metal pollutants are common occurrences in DWDS. In this study, a simulation of stagnant drinking water was applied to investigate the changes in water quality and microbial risks resulting from the simultaneous intrusion of trace metal pollutants under stagnation conditions, using a metagenomic approach. The differential expression of functional genes reflects the adaptive mechanisms of bacteria in response to the stress of trace metal pollutants. For the bacterial community in stagnant drinking water, Pseudomonadata is the major component. Many pathogenic bacteria have been found in stagnant drinking water, with the highest proportions being Salmonella enterica and Pseudomonas aeruginosa, which may exacerbate by the induction of trace amounts of Al. Several antibiotic resistance genes have been found in stagnant drinking water, with the highest abundance being macB, evgS, and tetA. Under the stress of trace metal pollutants, the overall exposure risk of ARGs has increased The experimental results also indicate that even the presence of trace Fe can amplify correlation of ARGs and pathogens, potentially leading to more serious hiddenly microbial risks. This study reveals the imperceptible microbial risks posed by the simultaneous invasion of stagnant and trace metal pollutants in daily drinking water and provides scientific warnings for drinking water safety.

饮用水输配管网系统（Drinking Water Distribution System, 简称DWDS）是保障民众饮水安全的最后一道防线，但其内部或潜藏诸多不易察觉的风险隐患。水质停滞与微量金属污染物侵入，是DWDS中较为常见的问题。本研究采用宏基因组学（metagenomic）分析方法，构建饮用水停滞模拟体系，探究停滞条件下微量金属污染物同步侵入时，水质变化与微生物风险的演化规律。功能基因的差异表达，可反映细菌应对微量金属污染物胁迫的适应性调控机制。停滞饮用水中的细菌群落以假单胞菌门（Pseudomonadata）为优势类群。研究在停滞饮用水中检出多种致病菌，其中以肠炎沙门氏菌（Salmonella enterica）和铜绿假单胞菌（Pseudomonas aeruginosa）占比最高，且微量铝（Al）的存在可能加剧该类风险。本研究同时检出多种抗生素抗性基因（antibiotic resistance genes, 简称ARGs），其中丰度最高的为macB、evgS与tetA。在微量金属污染物的胁迫作用下，抗生素抗性基因的整体暴露风险有所上升。实验结果还显示，即便仅存在微量铁（Fe），也会强化抗生素抗性基因与致病菌之间的关联，进而可能引发更为严重的隐性微生物风险。本研究揭示了日常饮用水中停滞状态与微量金属污染物同步侵入所带来的隐性微生物风险，可为饮用水安全保障提供科学预警依据。