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2Q - Online Biomonitoring (WEP/160) A Fibre-Optic Probe for Simple, Rapid Detection of E. coli and Total Coliform Bacteria in Water. Brown, Stephen1, Marcotte, Eric1, Yeung, Natasha1, Ley, Arthur1, Gilmour, Christie1, Brown, Melanie1, Aston, Peter1, 1 Queen's University, Kingston, Ontario, Canada ABSTRACT- Eschericia coli and related bacterial contaminants are the key targets of efforts to provide clean and safe drinking water. Monitoring of source waters, treated waters and waters in distribution systems is critical to ensuring the safety of a water supply. Current tests for E.coli and other coliforms require sample collection, transport to a laboratory facility, and then a 24-hour incubation period to get a result. Overall turn-around between sampling and communication of results is typically two days. The goal of our project is to develop a detection technology which is rapid and sensitive, yet simple enough to be incorporated into a remote and automated monitoring system. This will eliminate the need to ship samples to an external laboratory and communicate results back, providing same-day results at minimal cost. Our test is a modified version of standard E.coli tests where a sample is incubated in a solution containing a fluorogenic substrate, such as 4-methyl-umbelliferyl-b-glucuronide (MUG). These targeted substrates indicate the presence of glucuronidase enzyme, the accepted indicator of E.coli in water samples. Our new system uses a custom designed substrate and a fibre-optic probe which detects only the product generated by the enzyme. Fluorescence is continually monitored by the instrument, instead of at a fixed time after incubation, providing the earliest possible indication of a positive sample. Human judgment of the fluorescence intensity is not required, and the probe can extract the optical signal even from samples which are coloured, turbid or have other fluorescent substances in them. By tracking the fluorescence signal over time, we can estimate the number of cells present in the initial sample, providing a quantitative test. Results of a pilot study on raw water samples will be discussed. Key words: coliform, E.coli, fibre-optic probe, detection |
