Performance of an Electrostatic Precipitator with Superhydrophobic Surface when Collecting Airborne Bacteria

Modern bioaerosol sampling and analysis techniques that enable rapid detection of low bioagent concentrations in various environments are needed to help us understand the causal relationship between adverse health effects and bioaerosol exposures and also to enable the timely biohazard detection in case of intentional release. We have developed a novel bioaerosol sampler, an electrostatic precipitator with superhydrophobic surface (EPSS), where a combination of electrostatic collection mechanism with superhydrophobic collection surface allows for efficient particle collection, removal, and concentration in water droplets as small as 5 mu L. The sampler's performance at different sampling flow rates and sampling times was tested with two common bacteria: Pseudomonas fluorescens and Bacillus subtilis. The collection efficiency was determined using the traditional method of microscopic counting as well as the whole-cell quantitative real-time polymerase chain reaction assay (QPCR). The tests indicated that the new sampler achieves collection efficiency as high as 72%. A combination of the satisfactory collection efficiency and the small collecting water droplet volumes allowed achieving sample concentration rates that exceed 1 x 10(6). In addition, the collection efficiency for both bacteria obtained by the two different methods was not statistically different, indicating the sampler's compatibility with the PCR-based sample analysis techniques. In addition, the whole-cell QPCR does not require DNA extraction prior to the PCR reaction which offers faster sample processing. Very high concentration rates achieved with the new sampler as well as its compatibility with the QPCR methodology point toward its suitability for detecting low concentrations of airborne bacterial agents in various environments.