KWR Watercycle Research Institute, Groningenhaven 7, P.O. Box 1072, 3430 BB Nieuwegein, the Netherlands.
Appl Environ Microbiol. 2011 Oct;77(20):7321-8. doi: 10.1128/AEM.05575-11. Epub 2011 Aug 26.
The study whose results are presented here aimed at identifying free-living protozoa (FLP) and conditions favoring the growth of these organisms and cultivable Legionella spp. in drinking water supplies in a tropical region. Treated and distributed water (±30°C) of the water supplies of three Caribbean islands were sampled and investigated with molecular techniques, based on the 18S rRNA gene. The protozoan host Hartmannella vermiformis and cultivable Legionella pneumophila were observed in all three supplies. Operational taxonomic units (OTUs) with the highest similarity to the potential or candidate hosts Acanthamoeba spp., Echinamoeba exundans, E. thermarum, and an Neoparamoeba sp. were detected as well. In total, 59 OTUs of FLP were identified. The estimated protozoan richness did not differ significantly between the three supplies. In supply CA-1, the concentration of H. vermiformis correlated with the concentration of Legionella spp. and clones related to Amoebozoa predominated (82%) in the protozoan community. These observations, the low turbidity (<0.2 nephelometric turbidity units [NTU]), and the varying ATP concentrations (1 to 12 ng liter(-1)) suggest that biofilms promoted protozoan growth in this supply. Ciliophora represented 25% of the protozoan OTUs in supply CA-2 with elevated ATP concentrations (maximum, 55 ng liter(-1)) correlating with turbidity (maximum, 62 NTU) caused by corroding iron pipes. Cercozoan types represented 70% of the protozoan clones in supply CA-3 with ATP concentrations of <1 ng liter(-1) and turbidity of <0.5 NTU in most samples of distributed water. The absence of H. vermiformis in most samples from supply CA-3 suggests that growth of this protozoan is limited at ATP concentrations of <1 ng liter(-1).
本研究旨在鉴定自由生活原生动物（FLP）和有利于这些生物体生长的条件，并在热带地区的饮用水供应中培养可培养的军团菌属。使用分子技术，基于 18S rRNA 基因，对来自三个加勒比岛屿的供水处理和分配水（±30°C）进行采样和调查。在所有三个供应品中都观察到原生动物宿主哈氏变形虫和可培养的嗜肺军团菌。还检测到与潜在或候选宿主棘阿米巴属、Echinamoeba exundans、E. thermarum 和 Neoparamoeba sp. 具有最高相似性的分类操作单元 (OTU)。总共鉴定出 59 个 FLP OTU。三个供应品之间的原生动物丰富度没有显著差异。在供应 CA-1 中，哈氏变形虫的浓度与军团菌属的浓度相关，并且在原生动物群落中占主导地位的与变形虫相关的克隆（82%）。这些观察结果、低浊度（<0.2 浊度单位 [NTU]）和变化的 ATP 浓度（1 至 12 ng 升(-1)）表明，生物膜促进了该供应品中的原生动物生长。纤毛虫代表供应 CA-2 中 25%的原生动物 OTU，具有较高的 ATP 浓度（最高为 55 ng 升(-1)），与腐蚀铁管引起的浊度（最高为 62 NTU）相关。在供应 CA-3 中，原生动物克隆的 Cercozoan 类型占 70%，大多数分配水样本的 ATP 浓度<1 ng 升(-1)，浊度<0.5 NTU。在供应 CA-3 的大多数样本中均未发现哈氏变形虫，这表明在 ATP 浓度<1 ng 升(-1)时，该原生动物的生长受到限制。
