AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Potential Effects of Agar Plate Volume on Bioaerosol Impactor Measurement Accuracy
JENNIFER THERKORN, Gediminas Mainelis, Rutgers, The State University of New Jersey
Abstract Number: 750 Working Group: Instrumentation and Methods
Abstract Understanding how agar volume in bioaerosol impactors influences the efficiency of microorganism collection and preservation of their viability may lead to more efficient bioaerosol sampling. Optimizing sampling efficiency of impactors can allow for more accurate estimation of bioaerosol concentrations. Therefore, this research investigated how varying plate agar volume in impactors may affect accuracy of measured bioaerosol concentrations. The BioStage Impactor (SKC Inc., Eighty Four, PA), a single-stage Andersen N6-equivalent, was used to sample bacterial aerosols generated in a laboratory test chamber while the amount of agar in the sampler varied – 20, 35, or 50mL. These bacterial aerosols included a hardy (Bacillus subtilis) and sensitive (Escherichia coli) species. Using a BioStage Impactor as a reference with constant agar volume, outdoors sampling was also performed for both bacterial and fungal bioaerosols with varying agar amounts in a second BioStage Impactor, the Sampl’air (AES-Chemunex Inc., Princeton, NJ) and the SAS Super 180 (Bioscience International, Rockville, MD) impactors. For laboratory experiments with E. coli and B. subtilis, single factor ANOVA resulted in statistically significant differences in number of colony-forming units between the 20, 35, and 50mL volumes of agar (p-value < 0.05). Post hoc Sheffe’s test showed that 20mL agar volume resulted in statistically significantly fewer E. coli colony-forming units than tests done with either 35mL or 50mL of agar. Preliminary results with B. subtilis suggest an opposite trend with 50mL agar volume producing the lowest number of colony-forming units. In general, for bioaerosols in the laboratory and outdoors, trends could be seen of increasing colony-forming units as agar volume is adjusted to 35mL. This suggests there may be an optimal volume of agar for which there is both sufficient removal of biological particles from the airstream as well as increased maintenance of collected microorganism viability.