Investigation of live and dead status of airborne bacteria using UVAPS with LIVE/DEAD® BacLight Kit

Although the amount of allergens and toxins being originated from viable bacteria is higher than that from dead bacteria, monitoring concentrations of dead bacteria as well as live bacteria is an important issue related to human health. The ultraviolet aerodynamic particle sizer (UVAPS) is an instrument to measure the size distribution of only viable bioaerosols. Therefore, the main objective of this study is to detect percentages of dead as well as live airborne bacteria by using a LIVE/DEAD BacLight Bacterial Viability Kit (L7012, Molecular probes, USA) together with UVAPS. Two different bacteria species, Escherichia coli (E.coli) and Micrococcus luteus (M. luteus), were used for tests. Percentages of fluorescence emitted from these bacteria were compared with those from standard PSL and dust particles. The increased percentages for dead E. coli and dead M. luteus were 41% and 75%, respectively, while this kit did not show any effective influence on fluorescence percentages of polystyrene latex and dust particles. Field test was carried out in various indoor environments to investigate percentages of live and dead airborne bacteria.