Based on metagenomic shotgun sequencing, the viral community structure, potential hosts, and specific functional genes in key monitoring sites of a typical drinking water supply system were explored. The result revealed the presence of massive unclassified viral species, with the dominance of double-stranded DNA viruses occupying 94%–100% of viral abundance. The phages Siphoviridae and Myoviridae were identified as the major known taxa. Conventional and advanced treatment processes reduced viral richness, diversity, and replication potentials, while the richness and diversity slightly increased after passing water supply pipe network. Both treatment processes restrained the roles of viruses in mediating the exchange of auxiliary metabolic genes (AMGs). Viral genomes in source water possessed various AMGs involved in energy metabolism and biosynthesis of carbohydrates, amino acids, and cofactors, which could contribute to bacterial host metabolization. However, after conventional treatment, they mainly encoded penicillin-binding proteins. Notably, in the water sample with a long-term exposure to hospital clinic settings, the abundance of viruses (35%) carrying antibiotic resistance genes (ARGs) was much higher than those (≤ 2.6%) of other samples. This study highlighted the significant impacts of drinking water treatment processes, transport pipe networks, and environmental risk exposure on viral guilds and functions, and provided a theoretical basis for optimizing operation and management of water supply systems. 

water supply system, viral community, potential hosts, auxiliary metabolic genes (AMGs), antibiotic resistance genes (ARGs), metagenomics

基于宏基因组测序, 对饮用水供应系统重要监测断面的病毒群落结构、潜在宿主和特定功能基因开展研究。结果表明, 该类系统中存在大量未知分类的病毒, 双链DNA病毒丰度为94%~100%。Siphoviridae和Myoviridae等噬菌体是已知病毒的主要类群。常规净水工艺和深度处理可降低病毒物种丰富度、多样性和潜在活跃度, 经过输配管网后, 丰富度和多样性有所回升。水处理过程抑制了病毒作为辅助代谢基因交换媒介的作用, 水源地病毒主要携带与能量代谢、糖类/氨基酸/辅因子合成有关的多样化基因, 可提高细菌宿主的新陈代谢能力。常规净水工艺处理后, 病毒主要编码青霉素结合蛋白辅助代谢基因。值得注意的是, 长期置于医院环境的样本中携带抗生素抗性基因的病毒丰度(35%)远远高于其他样本(≤ 2.6%), 且抗性基因种类更加多样化。研究结果阐释了饮用水处理过程、管网输配和环境风险暴露对病毒群落和功能的显著影响, 可为给水系统后续运营管理的优化提供理论依据。