Valster Rinske M, Wullings Bart A, Bakker Geo, Smidt Hauke, van der Kooij Dick
KWR, Watercycle Research Institute, Groningenhaven 7, P.O. Box 1072, 3430 BB Nieuwegein, The Netherlands.
Appl Environ Microbiol. 2009 Jul;75(14):4736-46. doi: 10.1128/AEM.02629-08. Epub 2009 May 22.
Free-living protozoan communities in water supplies may include hosts for Legionella pneumophila and other undesired bacteria, as well as pathogens. This study aimed at identifying free-living protozoa in two unchlorinated groundwater supplies, using cultivation-independent molecular approaches. For this purpose, samples (<20 degrees C) of treated water, distributed water, and distribution system biofilms were collected from supply A, with a low concentration of natural organic matter (NOM) (<0.5 ppm of C), and from supply B, with a high NOM concentration (7.9 ppm of C). Eukaryotic communities were studied using terminal restriction fragment length polymorphism and clone library analyses of partial 18S rRNA gene fragments and a Hartmannella vermiformis-specific quantitative PCR (qPCR). In both supplies, highly diverse eukaryotic communities were observed, including free-living protozoa, fungi, and metazoa. Sequences of protozoa clustered with Amoebozoa (10 operational taxonomic units [OTUs]), Cercozoa (39 OTUs), Choanozoa (26 OTUs), Ciliophora (29 OTUs), Euglenozoa (13 OTUs), Myzozoa (5 OTUs), and Stramenopiles (5 OTUs). A large variety of protozoa were present in both supplies, but the estimated values for protozoan richness did not differ significantly. H. vermiformis was observed in both supplies but was not a predominant protozoan. One OTU with the highest similarity to Acanthamoeba polyphaga, an opportunistic human pathogen and a host for undesired bacteria, was observed in supply A. The high level of NOM in supply B corresponded with an elevated level of active biomass and with elevated concentrations of H. vermiformis in distributed water. Hence, the application of qPCR may be promising in elucidating the relationship between drinking water quality and the presence of specific protozoa.
供水系统中的自由生活原生动物群落可能包括嗜肺军团菌和其他有害细菌以及病原体的宿主。本研究旨在使用非培养分子方法鉴定两种未氯化的地下水源中的自由生活原生动物。为此,从低天然有机物(NOM)浓度(<0.5 ppm碳)的A供水系统和高NOM浓度(7.9 ppm碳)的B供水系统中采集了处理水、配水和配水系统生物膜的样本(<20摄氏度)。使用末端限制性片段长度多态性和部分18S rRNA基因片段的克隆文库分析以及一种蠕虫哈特曼原虫特异性定量PCR(qPCR)研究了真核生物群落。在两个供水系统中均观察到高度多样化的真核生物群落,包括自由生活原生动物、真菌和后生动物。原生动物序列与变形虫门(10个操作分类单元[OTU])、丝足虫门(39个OTU)、领鞭毛虫门(26个OTU)、纤毛虫门(29个OTU)、眼虫门(13个OTU)、顶复门(5个OTU)和不等鞭毛类(5个OTU)聚类。两个供水系统中都存在各种各样的原生动物,但原生动物丰富度的估计值没有显著差异。在两个供水系统中均观察到蠕虫哈特曼原虫,但它不是主要的原生动物。在A供水系统中观察到一个与多食棘阿米巴(一种机会性人类病原体和有害细菌的宿主)相似度最高的OTU。B供水系统中高浓度的NOM与活性生物量的增加以及配水中蠕虫哈特曼原虫浓度的升高相对应。因此,qPCR在阐明饮用水质量与特定原生动物存在之间的关系方面可能很有前景。