PDF(Pubmed)
Abstract：
Hot water building plumbing systems are vulnerable to the proliferation of opportunistic pathogens (OPs), including Legionella pneumophila and Mycobacterium avium. Implementation of copper as a disinfectant could help reduce OPs, but a mechanistic understanding of the effects on the microbial community under real-world plumbing conditions is lacking. Here, we carried out a controlled pilot-scale study of hot water systems and applied shotgun metagenomic sequencing to examine the effects of copper dose (0-2 mg/L), orthophosphate corrosion control agent, and water heater anode materials (aluminum vs magnesium vs powered anode) on the bulk water and biofilm microbiome composition. Metagenomic analysis revealed that, even though a copper dose of 1.2 mg/L was required to reduce Legionella and Mycobacterium numbers, lower doses (e.g., ≤0.6 mg/L) measurably impacted the broader microbial community, indicating that the OP strains colonizing these systems were highly copper tolerant. Orthophosphate addition reduced bioavailability of copper, both to OPs and to the broader microbiome. Functional gene analysis indicated that both membrane damage and interruption of nucleic acid replication are likely at play in copper inactivation mechanisms. This study identifies key factors (e.g., orthophosphate, copper resistance, and anode materials) that can confound the efficacy of copper for controlling OPs in hot water plumbing.
摘要：
热水建筑管道系统容易受到机会病原体（OPs）的扩散，包括嗜肺军团菌和鸟分枝杆菌。铜作为消毒剂的实施可以帮助减少OPs，但是缺乏对现实管道条件下微生物群落影响的机械理解。这里,我们对热水系统进行了受控的中试规模研究，并应用shot弹枪宏基因组测序来检查铜剂量（0-2mg/L）的影响，正磷酸盐缓蚀剂,和热水器阳极材料(铝vs镁vs供电阳极)上的散装水和生物膜微生物组组成。宏基因组分析显示，即使需要1.2毫克/升的铜剂量来减少军团菌和分枝杆菌的数量，较低的剂量(例如，≤0.6mg/L)可测量地影响更广泛的微生物群落，表明在这些系统中定植的OP菌株具有高度的铜耐受性。正磷酸盐的添加降低了铜的生物利用度，OPs和更广泛的微生物组。功能基因分析表明，膜损伤和核酸复制中断都可能在铜失活机制中起作用。这项研究确定了关键因素(例如，正磷酸盐,铜电阻，和阳极材料），可以混淆铜在热水管道中控制OPs的功效。
