Concentration and Viability of Bacterial Aerosols Associated with Weather in Asian Continental Outflow: Current Understanding

Abstract

Constituting a major fraction of bioaerosols, airborne bacteria take part in various atmospheric processes. Studies have suggested that airborne bacteria likely play an important role in cloud formation and consequently influence the solar radiation transfer and chemical conversions in the atmosphere, in addition to acting as links between geographically isolated microbial communities. However, how bacteria are dispersed in airflows remains poorly understood, because of the lack of reliable methods to describe the variations of airborne bacteria responding to changes in weather. We developed a simple method based on epifluorescence enumeration using LIVE/DEAD BacLight stain, by which we measured the concentrations of viable and non-viable bacterial cells in open air at a time resolution of 1 h or less. Although this method is labor-intensive, laboratory experiments and applications in field observations have demonstrated its reliability and effectiveness in studies on the correlation between airborne bacteria and Asian dust, the dependence of airborne bacteria on regional and synoptic weather, and the presence of bacteria in rainwater. In this short review, we briefly introduce the method, report the progress with its application to bacteria in Asian continental outflow, address the significance of meteorological factors in controlling the variation of airborne bacteria, and give perspectives on future studies in terms of the dynamics of bacterial aerosols in the atmosphere.