Fluorochrome in Monitoring Indoor Bioaerosols

In this study total concentration, viability, culturability of indoor and outdoor bioaerosols in ten residential environments were studied by using a cultivating method and an epifluorescence microscopy method with fluorochrome (EFM/FL) using four different dyes (AO, DAPI, PI, and YOPRO-1). Results from the EFM/FL were then compared with those from the traditional cultivating method. The total indoor microbial cell concentrations measured by EFM/FL was 630 to 5200 times higher than that measured by the cultivating method; ranging from 1.38 x 10(6) to 4.48 x 10(6)cells/m(3) (microbial cells per cubic meter) with AO staining, and from 7.84 x 10(5) to 2.75 x 10(6) cells/m(3) with DAPI staining, compared with the average concentration of 721 CFU/m(3) for bacteria and 587 CFU/m(3) for fungi by the cultivating methods. The viability of bioaerosols ranged from 0.63 to 0.92 by EFM/FL with PI staining, from 0.19 to 0.72 by EFM/FL with YOPRO-1 staining, and from 0.0002 to 0.0015 by the cultivating method. The viability determined by EFM/FL was much higher than the culturability. In summary, the total microbial cell concentration and viability were highly underestimated by the cultivating method. In conclusion, EFM/ FL method can effectively assess the total concentration and viability of bioaerosols in indoor samples.