The 2nd Generation ColiSense system for the detection of E. coli in bathing waters

Marine and estuarine water bodies are hubs for recreation, education, socio- cultural and wellbeing activities and are seen as critical resources that need to be protected. However, these ecosystems are frequently contaminated by faecal pollution from a range of sources such as treated sewage effluent, agricultural runoff, and raw sewage discharges. This endangers the provided ecosystem services and represents a health risk for its users. Culture-based methods currently in use are slow to provide results and not ideal when data is needed for rapid decision support. Field test kits are thus required to provide bacterial water quality results in a time-frame that enables decision support and risk mitigation. ColiSense system was previously developed for the rapid detection of faecal pollution indicator E. coli and relies on the detection of E. coli bio-marker enzyme, beta-glucuronidase (GUS). The system was designed to be portable, low cost and provide results within 75 min from sample collection. A range of environmental trials have successfully demonstrated the system capabilities and the relationship with the standard culturebased methods. Through these trials, key shortcomings have also been identified in regards to device functionality and the ease of use. An improved 2nd generation device was developed to address these requirements and is presented here. The 2nd generation system streamlines the conversion of raw signal to processed GUS activities, stores calibration curve coefficients and raw data and allows user to carry out quality control procedures. Analytical performance of the 2nd generation prototype has been established in the laboratory and is comparable with the analytical performance of the 1st prototype. In addition, results from field trials demonstrate similar performance in samples contaminated with E. coli, and a good concordance with the standard culture-based method.