Evaluation of microbial samplers for bacterial microorganisms

The influences of physical factors, sampling time, and how rates on total recovery rate of airborne bacteria were evaluated in a chamber by three sampling methods: AGI-30 all-glass impingers, Nuclepore filtration and elution method, and gelatin filters. The influence of the biological factor, microorganism hardiness, was assessed by using sensitive Escherichia coli (E. coli) and hardy Bacillus subtilis (B. subtilis) spores. It was found that colony or relative survival of sensitive E, coli was much lower than those of hardy B, subtilis spores by the evaluated three sampling methods. Sampling flow rate did not have a significant influence on the bacterial recovery by the three sampling methods, However, the relative survival of sensitive E, coli collected on Nuclepore and gelatin filters became lower as the sampling time increased because of dehydration effects. For hardy B, subtilis spores, it was demonstrated that recovery by gelatin filter was comparable to that by impinger. In conclusion, it was found that impingers could perform much better than filtration methods for sampling airborne bacterial bioaerosols.