Comparison of molecular and total ATP-based analytical methods with culture for the analysis of bioaerosols

The microbial content of indoor air is an increasingly important issue. High microbial load is associated with various adverse health effects, such as infectious disease, asthma, and toxicosis. The most commonly applied method for analyzing airborne microorganisms is a six-stage Anderson microbiological impactor and subsequent cultivation on agar plates. However, such culture can take several days to produce results, and only a small proportion of viable microorganisms are culturable. Thus, cultivation cannot rapidly identify the degree of health risk or fully characterize microbial communities related to adverse health effects. We sampled bioaerosols using both a high volume SpinCon sampler and a six-stage Andersen microbial impactor. These samples were assayed by culturing, real-time TaqMan PCR, and ATP bioluminescence. We found a significant positive association between real-time TaqMan and cultivation, but not between total ATP and cultivation. Thus, a real-time TaqMan PCR assay could be used in place of cultivation to assess microbial air quality. Finally, when microbial communities were characterized using denaturing gradient gel electrophoresis (DGGE) and principal component analysis (PCA), a seasonal clustering of microbial profiles was observed.