Fast detection and identification of bacteria in potable water
The quality and safety of drinking water is of major importance for human life. Current analytical methods recognizing viable bacteria in potable water are time consuming due to a required cultivation step. Fast and automated detection of water borne pathogenic microorganisms with high sensitivity and selectivity is still a challenging task. We report on a novel biosensor system using micromechanical filters with nano sized pores to capture and enrich bacteria on the filter surface. Thus the accumulated organisms are accessible to different detection methods using fluorescent probes. depending on the kind of detection - specific (identification of a certain species) or unspecific (total amount of cells) - different assays are applied. For non-specific detection we use fluorescent dyes that bind to or intercalate in the DNA molecules of the bacteria. Upon binding, the fluorescent signal of the dyes increases by a factor of 1000 or more. Additionally, we use enzyme substr ates for the detection of active ce lls. The whole detection process is automated by integrating the microsieves into a fluidic system together with a high performance fluorescence detector. To ensure realistic conditions, real potable water, i.e. including particles, has been spiked with defined amounts of microorganisms. Thus, sampling, enriching and detection of microorganisms - all with a single micromechanical filter - is not only possible with ideal media, e.g. laboratory buffer solutions, but also with tap water. These results show the potential of microfilters for several applications in fast pathogen detection.