In collaboration with South East Water, this research focuses on elucidating the contribution of human faecal pollution to eutrophication processes in a reservoir site using microbial source tracking (MST) tools. High nutrient inputs into water bodies, such as reservoirs, can result in an increase in algal blooms and costs associated with water treatment. Cyanobacteria (often known as ‘blue-green algae’) can be harmful to human health because of their production of harmful toxins. MST encompasses techniques that aim to distinguish source(s) of faecal contamination in surface and ground waters.
One relatively simple, low-cost and effective technique that has been successfully used to discriminate between human and non-human faecal contamination, involves the detection and enumeration of bacteriophages (viruses) capable of infecting anaerobic bacteria (Bacteroides spp.) present in human waste. Application of this low-cost MST method (Bacteroides GB124 phage method) accompanied the detection and enumeration of widely used molecular MST markers (human-specific (Hubac) and ruminant-specific (RuBac). This comparative approach allows the efficacy of the methods (in terms of method ‘specificity’ and ‘sensitivity’) to be established (when determining the source(s) of small- scale faecal contributions) and should improve the understanding of the contribution of human faecal inputs on water quality in this reservoir site.
The project commenced in 2016 and ended in 2017.
This study aimed to determine if human-specific bacteriophages infecting a Bacteroides host strain (GB124) can distinguish human-faecal inputs into reservoirs from small-scale sources, such as those expected from individual septic tanks and small feeder streams.
The project aimed:
The results of this study suggested that it is possible to use GB124 bacteriophages to distinguish small-scale discrete sources of human faecal contamination. In addition, the results indicated that low-cost bacteriophage MST methods could be used to screen larger volumes of samples in studies such as these, allowing more expensive molecular methods to be focused on highlighted sites. This information is valuable as it is enabling the water company to fully understand nutrient source pathways, which will permit them to develop a strategy for the management of this reservoir and to future-proof the water quality of the asset at this site. This work is all part of a new catchment management initiative launched by South East Water (SEW), which is helping the company to understand the causes of drinking water quality deterioration. Research such as this will enable them to determine which measures are required in order to address water quality problems and safeguard drinking water sources in the future.
Zones of lysis from bacteriophages capable of infecting human-specific Bacteroides host strain GB124
Paper to follow on publication
Simon Lohrey – South East Water