Liu Jingqing, Ren Hongxing, Ye Xianbei, Wang Wei, Liu Yan, Lou Liping, Cheng Dongqing, He Xiaofang, Zhou Xiaoyan, Qiu Shangde, Fu Liusong, Hu Baolan
College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, 310058, China.
Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China.
Appl Microbiol Biotechnol. 2017 Jan;101(2):749-759. doi: 10.1007/s00253-016-7887-8. Epub 2016 Oct 19.
Biofilms in the pipe wall may lead to water quality deterioration and biological instability in drinking water distribution systems (DWDSs). In this study, bacterial community radial-spatial distribution in biofilms along the pipe wall in a chlorinated DWDS of East China was investigated. Three pipes of large diameter (300, 600, and 600 mm) were sampled in this DWDS, including a ductile cast iron pipe (DCIP) with pipe age of 11 years and two gray cast iron pipes (GCIP) with pipe ages of 17 and 19 years, and biofilms in the upper, middle, and lower parts of each pipe wall were collected. Real-time quantitative polymerase chain reaction (qPCR) and culture-based method were used to quantify bacteria. 454 pyrosequencing was used for bacterial community analysis. The results showed that the biofilm density and total solid (TS) and volatile solid (VS) contents increased gradually from the top to the bottom along the pipe wall. Microorganisms were concentrated in the upper and lower parts of the pipe wall, together accounting for more than 80 % of the total biomass in the biofilms. The bacterial communities in biofilms were significantly different in different areas of the pipe wall and had no strong interaction. Compared with the upper and lower parts of the pipe wall, the bacterial community in the middle of the pipe wall was distributed evenly and had the highest diversity. The 16S rRNA genes of various possible pathogens, including Escherichia coli, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Salmonella enterica, were detected in the biofilms, and the abundances of these possible pathogens were highest in the middle of the pipe wall among three areas. The detachment of the biofilms is the main reason for the deterioration of the water quality in DWDSs. The results of this study suggest that the biofilms in the middle of the pipe wall have highly potential risk for drinking water safety, which provides new ideas for the study of the microbial ecology in DWDS.
管壁中的生物膜可能导致饮用水分配系统（DWDSs）中的水质恶化和生物稳定性问题。在本研究中，对中国东部一个氯化DWDS中沿管壁生物膜内细菌群落的径向空间分布进行了调查。在该DWDS中对三根大口径管道（300、600和600毫米）进行了采样，包括一根使用年限为11年的球墨铸铁管（DCIP）和两根使用年限分别为17年和19年的灰铸铁管（GCIP），并收集了每根管壁上部、中部和下部的生物膜。采用实时定量聚合酶链反应（qPCR）和基于培养的方法对细菌进行定量。使用454焦磷酸测序法进行细菌群落分析。结果表明，生物膜密度以及总固体（TS）和挥发性固体（VS）含量沿管壁从顶部到底部逐渐增加。微生物集中在管壁的上部和下部，两者合计占生物膜中总生物量的80%以上。生物膜中的细菌群落在管壁的不同区域存在显著差异，且没有强烈的相互作用。与管壁的上部和下部相比，管壁中部的细菌群落分布均匀且多样性最高。在生物膜中检测到了各种可能病原体的16S rRNA基因，包括大肠杆菌、表皮葡萄球菌、铜绿假单胞菌和肠炎沙门氏菌，这些可能病原体的丰度在三个区域中以管壁中部最高。生物膜的脱落是DWDSs水质恶化的主要原因。本研究结果表明，管壁中部的生物膜对饮用水安全具有很高的潜在风险，为DWDS中微生物生态学的研究提供了新思路。
