Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, Northern Territory, Australia.
Global and Tropical Health, Menzies School of Health Research, Darwin, Northern Territory, Australia.
PLoS Negl Trop Dis. 2019 Sep 5;13(9):e0007672. doi: 10.1371/journal.pntd.0007672. eCollection 2019 Sep.
In the wet-dry tropics of Northern Australia, drinking water in remote communities is mostly sourced from bores accessing groundwater. Many aquifers contain naturally high levels of iron and some are shallow with surface water intrusion in the wet season. Therefore, environmental bacteria such as iron-cycling bacteria promoting biofilm formation in pipes or opportunistic pathogens can occur in these waters. An opportunistic pathogen endemic to northern Australia and Southeast Asia and emerging worldwide is Burkholderia pseudomallei. It causes the frequently fatal disease melioidosis in humans and animals. As we know very little about the microbial composition of drinking water in remote communities, this study aimed to provide a first snapshot of the microbiota and occurrence of opportunistic pathogens in bulk water and biofilms from the source and through the distribution system of three remote water supplies with varying iron levels. Using 16s-rRNA gene sequencing, we found that the geochemistry of the groundwater had a substantial impact on the untreated microbiota. Different iron-cycling bacteria reflected differences in redox status and nutrients. We cultured and sequenced B. pseudomallei from bores with elevated iron and from a multi-species biofilm which also contained iron-oxidizing Gallionella, nitrifying Nitrospira and amoebae. Gallionella are increasingly used in iron-removal filters in water supplies and more research is needed to examine these interactions. Similar to other opportunistic pathogens, B. pseudomallei occurred in water with low organic carbon levels and with low heterotrophic microbial growth. No B. pseudomallei were detected in treated water; however, abundant DNA of another opportunistic pathogen group, non-tuberculous mycobacteria was recovered from treated parts of one supply. Results from this study will inform future studies to ultimately improve management guidelines for water supplies in the wet-dry tropics.
在澳大利亚北部的干湿热带地区，偏远社区的饮用水主要取自地下水井。许多含水层含有天然高浓度的铁，有些含水层较浅，在雨季地表水会渗透进来。因此，环境细菌，如促进管道生物膜形成的铁循环细菌或机会性病原体，可能存在于这些水中。一种在澳大利亚北部和东南亚流行并在全球范围内出现的机会性病原体是类鼻疽伯克霍尔德菌。它会导致人和动物患上经常致命的类鼻疽病。由于我们对偏远社区饮用水的微生物组成知之甚少，因此本研究旨在首次了解三个具有不同铁含量的偏远供水水源及其分配系统中总水中和生物膜中机会性病原体的微生物组成和存在情况。通过 16S-rRNA 基因测序，我们发现地下水的地球化学对未处理的微生物群有很大影响。不同的铁循环细菌反映了氧化还原状态和营养物质的差异。我们从含铁量较高的水井和含有铁氧化菌盖氏菌、硝化菌硝化螺旋菌和变形虫的多物种生物膜中培养和测序了类鼻疽伯克霍尔德菌。盖氏菌越来越多地用于供水的铁去除过滤器，需要更多的研究来检查这些相互作用。与其他机会性病原体一样，类鼻疽伯克霍尔德菌存在于低有机碳水平和低异养微生物生长的水中。在处理过的水中未检测到类鼻疽伯克霍尔德菌；然而，从一个供水系统的处理部分回收了另一种机会性病原体组，即非结核分枝杆菌的大量 DNA。本研究的结果将为未来的研究提供信息，最终改善干湿热带地区供水系统的管理指南。
