Comparison of Three Bioaerosol Samplers for Bacterial Diversity

Bioaerosols are critical components of the atmospheric environment, yet their accurate characterization remains challenging due to the lack of a standardized sampling methodology. In this study, we compared three commonly used bioaerosol samplers- a swirling collector, a condensational growth tube collector, and a cascade impactor-to evaluate their performance in capturing bacterial diversity, community composition, and number concentrations at two distinct locations on a university campus. The bacterial communities were analyzed using 16S rRNA gene amplicon sequencing. The results revealed significant differences in the bioaerosol number concentrations and the composition of bacterial communities across the samplers. Among the three samplers, the condensational growth tube collector recorded the highest overall concentration, with a lower alpha diversity than the other sampler types. Analysis of the 678 identified unique genera indicated that only 24% were collected by all three samplers, underscoring that no single device can comprehensively represent airborne bacterial diversity. However, all three samplers consistently identified distinct locational differences in key bacterial taxa, notably the increased abundance of agriculture-associated genera near the livestock-rearing facility. This indicates that each sampler was able to capture and reveal dominant genera under different environments. PERM-ANOVA results showed that the type of bioaerosol sampler was responsible for more variance in bacterial community composition than sampling location, highlighting the dominant role of sampler selection in shaping observed microbial profiles. Overall, the variability in performance of samplers may be influenced by factors such as particle size distribution, bacterial community composition, sampling mechanism, and sampling medium. These findings underscore the critical importance of selecting appropriate bioaerosol sampling instruments based on targeted microbial communities and specific environmental conditions; the findings also provide a framework for refining sampling methodologies to enhance the accuracy and comparability of bioaerosol studies.