Opportunistic pathogens and large microbial diversity detected in source-to-distribution drinking water of three remote communities in Northern Australia

Abstract

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.

Characterisation of Microbial Community Associated with Different Disinfection Treatments in Hospital hot Water Networks

“…In network with monochloramine treatment, Gallionella was the predominant genus. It is an iron oxidizing bacterium, aerobic microorganism that derive energy from the oxidation of iron from the ferrous state (Fe 2+ ) to the ferric state (Fe 3+ ) by accelerating the natural reaction between oxygen and ferrous ions in the water or on the surface of metal pipes such as galvanized iron, cast iron and steel pipes [60][61][62]. The presence of Gallionella has a potential negative effect on the pipes, due to the precipitation of its metabolism product (hydrated ferric hydroxide) reducing the pipes section [60].…”

Opportunistic Premise Plumbing Pathogens. A Potential Health Risk in Water Mist Systems Used as a Cooling Intervention

“…The conventional treatment that the scheme water goes through, a process involving the reduction of TDS to meet the standard of 500 mg/L set by the Australian Drinking Water Guidelines [61] could be the reason for this difference. The TDS composition of water in premise plumbing could include some inorganic salts and dissolved traces of organic matter as well as nutrients that leach from the internal surfaces of plumbing materials [62], and often promote the formation of biofilms on which premise plumbing pathogens grow, and when present in water supplies can serve as an energy source for microorganisms [63,64]. However, the effect of plumbing materials on the regrowth of opportunistic pathogens in WMS was not the focus of this study.…”

Microbial diversity in full-scale water supply systems through sequencing technology: a review

“…Chemical effects. Environmental factors such as temperature, [25][26][27] pH, 28,29 electrolyte type, 19,30,31 salinity, 32 dissolved particles, 26 dissolved oxygen (DO), 33,34 C/N ratio, 19 total nitrogen (TN), 25 total phosphorus (TP), 22 and organic matter 35,36 have been investigated, and veried to inuence the composition of the microbial community in drinking water. Zhang et al 30 investigated the bacterial communities during the outbreak and decline of an algal bloom in a drinking water reservoir.…”