AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
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Evaluation of Two Concentrating Techniques for Bioaerosol Quantification
HYEON-JU OH, Taewon Han, Gediminas Mainelis, Rutgers, The State University of New Jersey
Abstract Number: 237 Working Group: Bioaerosols
Abstract Concentration process is a critical step when preparing liquid-based bioaerosol samples because that allows measuring lower bioaerosol concentrations. Here we investigated the performance of two concentrating techniques: BioChromato evaporator and Concentrating Pipette Tip (CPT). The tests were performed with polystyrene latex (PSL) particles of 1.0 and 2.9 µm in diameter, Bacillus subtilis and Pseudomonas stutzeri bacterial cells, and bioaerosols collected outdoors. For outdoor field test, bioaerosol samples were collected using BioSampler (SKC Inc.) with 20 mL of collection liquid for 120 min, and concentrated by using BioChromato evaporator and CPT had 20-40 mL of initial liquid volume. For the evaporator, it took 30-150 min to reduce sample volume to 10 mL; for CPT, 20-40 seconds were sufficient to reduce the sample volume to 0.3-0.8 mL. The losses, quantified by microscopy as particle numbers before and after the concentration, for the evaporator were 6.6-21.5 % for 1.0, 2.9 µm PSL and B. subtilis bacterial cells; the losses for the CPT were 13.3-70.8 % for 1.0, 2.9 µm PSL, B. subtilis and P. stutzeri bacterial cells. In the culture-based analysis, losses of bacteria by the CPT were 51.4-76.9 % for B. subtilis and P. stutzeri. When outdoor samples were concentrated using the CPT, the losses based on culture-based analysis were 57.8-79.4 % for bacterial cells and fungal spores. However, there was no loss of both bacterial cells and fungal spores when analyzed by microscopy, most likely due to deagglomeration of cells during the washing step involving a detergent. These results suggest that both concentration techniques were able to minimize the sample volume. However one has to keep in mind the loss of particles, especially the culturable fraction, during the process.