Pennine Water Group, Department of Civil and Structural Engineering, Sir Frederick Mappin Building, University of Sheffield, Sheffield, S1 3JD, United Kingdom.
Theoretical Biology and Bioinformatics, Science for Life, Utrecht University, Hugo R. Kruytgebouw, Padualaan 8, 3584, CH, Utrecht, Netherlands.
Water Res. 2020 Dec 15;187:116416. doi: 10.1016/j.watres.2020.116416. Epub 2020 Sep 23.
Phosphate is routinely dosed to ensure regulatory compliance for lead in drinking water distribution systems. Little is known about the impact of the phosphate dose on the microbial ecology in these systems and in particular the endemic biofilms. Disturbance of the biofilms and embedded material in distribution can cause regulatory failures for turbidity and metals. To investigate the impact of phosphate on developing biofilms, pipe wall material from four independent pipe sections was mobilised and collected using two twin-flushing operations a year apart in a chlorinated UK network pre- and post-phosphate dosing. Intensive monitoring was undertaken, including turbidity and water physico-chemistry, traditional microbial culture-based indicators, and microbial community structure via sequencing the 16S rRNA gene for bacteria and the ITS2 gene for fungi. Whole metagenome sequencing was used to study shifts in functional characteristics following the addition of phosphate. As an operational consequence, turbidity responses from the phosphate-enriched water were increased, particularly from cast iron pipes. Differences in the taxonomic composition of both bacteria and fungi were also observed, emphasising a community shift towards microorganisms able to use or metabolise phosphate. Phosphate increased the relative abundance of bacteria such as Pseudomonas, Paenibacillus, Massilia, Acinetobacter and the fungi Cadophora, Rhizophagus and Eupenicillium. Whole metagenome sequencing showed with phosphate a favouring of sequences related to Gram-negative bacterium type cell wall function, virions and thylakoids, but a reduction in the number of sequences associated to vitamin binding, methanogenesis and toxin biosynthesis. With current faecal indicator tests only providing risk detection in bulk water samples, this work improves understanding of how network changes effect microbial ecology and highlights the potential for new approaches to inform future monitoring or control strategies to protect drinking water quality.
磷酸盐通常被投加以确保饮用水分配系统中铅的法规合规性。然而，对于磷酸盐剂量对这些系统中内源性生物膜的微生物生态学的影响，人们知之甚少，特别是在干扰生物膜和分布中的嵌入式材料方面，可能会导致浊度和金属的法规失效。为了研究磷酸盐对生物膜形成的影响，从英国氯化供水中四个独立的管道段中移动和收集了管壁材料，这些管道在磷酸盐投加前后一年进行了两次双冲洗操作。进行了密集监测，包括浊度和水物理化学特性、传统的微生物培养指标以及通过测序细菌的 16S rRNA 基因和真菌的 ITS2 基因来研究微生物群落结构。全基因组测序用于研究添加磷酸盐后功能特征的变化。作为操作结果，磷酸盐富水的浊度响应增加，特别是来自铸铁管。还观察到细菌和真菌的分类组成差异，这强调了微生物群落向能够利用或代谢磷酸盐的微生物的转变。磷酸盐增加了细菌（如假单胞菌、芽孢杆菌、马西利亚菌、不动杆菌）和真菌（如拟盘多毛孢菌、根毛菌和青霉菌）的相对丰度。全基因组测序显示，磷酸盐有利于革兰氏阴性菌细胞壁功能、病毒和类囊体相关的序列，但与维生素结合、甲烷生成和毒素生物合成相关的序列数量减少。由于目前的粪便指示物测试仅在批量水样中提供风险检测，因此这项工作提高了人们对管网变化如何影响微生物生态学的理解，并强调了采用新方法为未来监测或控制策略提供信息以保护饮用水质量的潜力。
