Rapid and specific SPRi detection of L. pneumophila in complex environmental water samples
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Legionellosis is a very devastating disease worldwide mainly due to unpredictable outbreaks in man-made water systems. Developing a highly specific and sensitive rapid detection system that detects only metabolically active bacteria is a main priority for water quality assessment. We previously developed a versatile technique for sensitive and specific detection of synthetic RNA. In the present work, we further investigated the performance of the developed biosensor for detection of Legionella pneumophila in complex environmental samples, particularly those containing protozoa. The specificity and sensitivity of the detection system were verified using total RNA extracted from L. pneumophila in spiked water co-cultured with amoebae. We demonstrated that the expression level of ribosomal RNA (rRNA) is extremely dependent on the environmental conditions. The presence of amoebae with L. pneumophila, especially in nutrition-deprived samples, increased the amount of L. pneumophila 15-fold after 1 week as measured through the expression of 16s rRNA. Using the developed surface plasmon resonance imaging (SPRi) detection method, we were also able to successfully detect L. pneumophila within 3 h, both in the presence and absence of amoebae in the complex environmental samples obtained from a cooling water tower. These findings suggest that the developed biosensing system is a viable method for rapid, real-time and effective detection not only for L. pneumophila in environmental samples but also to assess the risk associated with the use of water contaminated with other pathogens.
KeywordsBiosensors Nanoparticles/nanotechnology Nucleic acids (DNA | RNA) Optical sensors
We acknowledge the National Science and Engineering Research Council of Canada-Strategic and Discovery programme, Genome Canada/Genome Quebec and Nano-Quebec. The authors would also like to thank R. Tien Sing Young for helping with illustrations design, L. Li for the amoeba culture, Dr. K. Bowey for her comments on the manuscript and Dr. Sandra Imbeault for providing the environmental water samples. The work in the SPF laboratory is supported by NSERC Discovery Grant 418289-2012.
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