Detection of microorganisms in drinking water using fluorescence spectroscopy

To guarantee safe supply of drinking water, there is a need for fast, sensitive and robust techniques for early warning of potentially pathogenic microorganisms. An optical measurement system has been developed to spectrally study the UV-induced autofluorescence from single microorganisms in a water flow. Particles in the flow are detected with a continuous-wave laser whereby an ultraviolet laser pulse is fired and a spectrometer measures emitted fluorescence. Suspensions of Cryptosporidium parvum (Crypto), Bacillus atrophaeus (BG, a non-pathogenic simulant bacterial spore) and Escherichia coli (Ecoli), in distilled and tap water have been examined. The results from single particle measurements are compared to fluorescence emission spectra captured on suspensions with a fluorescence spectrometer and the strength and variability of single organism spectra, with respect to detection applications, is also investigated.