A synthetic biology approach to developing a biosensor for detection of pathogens in drinking water.

View all posters

Elizabeth Court, Paul Davison, Stuart Hunt and Catherine A. Biggs

University of Sheffield, United Kingdom

Vibrio cholerae is a waterborne pathogen that causes the acute diarrhoeal disease cholera which is prevalent in the developing world with 100-120,000 deaths per year. Current detection methods are lab based, with a timescale of hours to days, using fluorescent labelled antibodies or PCR to detect V. cholerae outer membrane proteins and DNA respectively. We are applying the principles of synthetic biology to produce a fast, simple, sensitive, mobile surveillance system that can be used in the field. The basis of the biosensor design is to detect chemicals involved in ‘quorum sensing’, the process by which bacteria communicate using secreted chemical signalling molecules to assess their population density. Under high cell density conditions V. cholerae produce the signalling molecule CAI-1 which is detected by the CqsS receptor protein causing downstream signalling proteins luxO and luxU to stimulate expression of Qrr genes and cause behavioural changes in the cell. The biosensor consists of a reporter component, and a sensor component of the CqsS-LuxU-LuxO gene cassette whose proteins will detect CAI-1 in a water sample and drive expression of reporter genes under the control of the Qrr promoter. The DNA components of the biosensor have been inserted into the pWH1274 expression plasmid and transformed into Acinetobacter baylyi ADP1 which is a useful robust host in terms of viability, maintenance and storage. Preliminary results show that the DNA components have been successfully incorporated into the plasmid and transformed into A.baylyi using reporter genes GFP and lux operon. We aim to present results of the specificity, sensitivity and operability of the biosensor in detecting V.cholerae in drinking water. Future work is to extend the application of this design of biosensors by looking at quorum sensing systems in other drinking water pathogens.