Analysis of Culturable Bacterial and Fungal Aerosol Diversity Obtained Using Different Samplers and Culturing Methods

Abstract

In this study, biological collection efficiencies and culturable bacterial and fungal aerosol diversities were investigated when different bioaerosol sampling tools and culturing methods were applied. The samplers included Reuter centrifugal sampler (RCS) High Flow, BioSampler, electrostatic sampler, gelatin filter, BioStage impactor, mixed cellulose ester (MCE) filter as well as gravitational settling methods. For culturable bacterial aerosol diversity, the colony-forming units (CFUs) were washed off from the agar plates, and further went through polymerase chain reaction- and denaturing gradient gel electrophoresis (PCR–DGGE). For culturable fungal aerosol diversity, microscopic identification method was applied. In general, the BioStage impactor, MCE filter, and the BioSampler remained robust when sampling culturable bioaerosols. The PCR–DGGE study revealed that the use of different samplers and culturing methods resulted in different culturable bioaerosol diversity. For indoor bacterial aerosols, the MCE filter with direct culturing on agar plates and the BioSampler resulted in the highest number of visible bands on DGGE gels, followed by the gravitational settling (26°C), the RCS High Flow, electrostatic sampler, and the MCE filter extracted. However, for outdoor bacterial aerosols, the BioStage impactor obtained the highest number of visible bands followed by the BioSampler, MCE filter, electrostatic sampler, the RCS High Flow, and gravitational settling at 26°C. When sampling fungal aerosols, the electrostatic sampler was observed to produce the highest diversity. Similar to previous studies, Alternaria, Cladosporium, and Aspergillus species were found to dominate the fungal community in most samples collected here. The results obtained here suggested that the sampler design, sampling environments, and culturing methods should be considered together when assessing the biological aerosol exposure.