Factors Affecting Survival of E.coli in Water

Pathogenic E. coli are responsible for causing outbreaks of haemorrhagic colitis and haemolytic uramic syndrome. In previous years, E. coli O157:H7 was responsible for a number of outbreaks, but more recently, other strains of E. coli have been implicated in outbreaks. In Scotland, 35% of E. coli cases were caused by non-O157 infection between 2014 and 2015 (Allison and Hanson 2015). Many cases result in hospitalisations, but can be fatal in severe cases or in areas where access to public healthcare is more difficult, for example, in developing countries.
E. coli can be spread by a number of environmental routes, but its persistence in surface waters is one of the most problematic. Its main reservoir is human and animal waste, so E. coli can be introduced into surface or ground waters via direct deposition, run-off or percolation through soil. Once in a water course, E. coli has the potential to be transported over long distances. This poses a public safety concern due to potential downstream contamination of recreational and shellfish production areas. Moreover, abstracted contaminated surface waters used for irrigation could allow viable E. coli to contaminate crops by internalisation of plant material. The percolation of E. coli through soils also poses a risk to the 1 % of the UK population who obtain their drinking water from private water supplies. The source of E. coli in this case tends to be either surrounding farmland or poorly maintained septic tanks. Once entering the food chain by these different methods, it can spread from person to person via the faecal-oral route. Despite improved regulatory measures, the frequencies of E. coli outbreaks in the UK have not significantly decreased. This, in part, is due to the fact that little is known about the factors that affect E. coli survival in the environment.
Our previous work showed that long-term survival of E. coli occurred in both low-nutrient lake waters and high-nutrient faecally contaminated puddle water compared to drinking troughs and river water (Avery et al. 2008). There was evidence that water chemistry and the indigenous microbial communities were involved in this observed persistence. The proposed project will focus on the biotic and abiotic factors that affect E. coli persistence in surface waters and drinking waters and elucidate possible survival mechanisms. The objectives of this project are:
1: Conduct field assessments to develop a field model of E. coli prevalence.
2: Determine the effects of water chemistry and indigenous microbial communities on E. coli persistence.
3: Test the effects of ecological interactions on E. coli persistence with artificial microbial communities.
4: Model E. coli persistence under various environmental conditions.

This project will provide excellent training in a number of skills including fieldwork, lab work (traditional microbiological methods and skills in molecular biology) and modelling (Baysian networks, structural equation modelling and community modelling using an agent based approach). The supervisors at The James Hutton Institute and the University of Stirling will work in an integrated way as part of the Centre for Human and Animal Pathogens in the Environment (HAP-E) group, and so the prospective student will benefit from interactions with staff that have a range of knowledge in environmental microbiology, molecular ecology, analytical chemistry, bioinformatics and modelling. Their affiliation with the University of Stirling will allow them access to a number of postgraduate training courses, which cover Project Management, Communication, Scientific Writing, Technical Training and Career Management.