Potential of an electronic nose for the early detection and differentiation between Streptomyces in potable water

Much attention has been focused on the production of musty-aroma compounds such as geosmin and their impact on the quality of fresh water and water-cultured raised fish and sea-food. At present, there are no efficient means of removing these off-flavours from water. Therefore, the rapid detection of geosmin-producing microorganisms, in particular the genus Streptomyces, at early stages of differentiation, is still the best option in preventing deterioration of water quality. We investigated the potential of an electronic nose consisting of an array of 14 conducting polymer sensors for the rapid and early detection of Streptomyces spores in reverse osmosis and tap water. Geosmin solutions in water at different concentrations were also prepared for headspace analysis in order to study the e-nose potential for detecting geosmin production in this environment. Normalised divergence data were analysed using principal component analysis (PCA) and discriminant function analysis (DFA). Data indicates that an e-nose could be employed to detect and monitor early activity of Streptomyces in water at different stages of differentiation, as well as to discriminate between different species based on their volatile production patterns. It also suggests that it could be used for monitoring geosmin production in water and possibly set threshold odour levels, as a routine task for specific water-screening purposes.