Microbial Ecology of the Planetary Boundary Layer

Aerobiology is a growing research area that covers the study of aerosols with a biological origin from the air that surrounds us to space through the different atmospheric layers. Bioaerosols have captured a growing importance in atmospheric process-related fields such as meteorology and atmospheric chemistry. The potential dissemination of pathogens and allergens through the air has raised public health concern and has highlighted the need for a better prediction of airborne microbial composition and dynamics. In this review, we focused on the sources and processes that most likely determine microbial community composition and dynamics in the air that directly surrounds us, the planetary boundary layer. Planetary boundary layer microbial communities are a mix of microbial cells that likely originate mainly from local source ecosystems (as opposed to distant sources). The adverse atmospheric conditions (i.e., UV radiation, desiccation, presence of radicals, etc.) might influence microbial survival and lead to the physical selection of the most resistant cells during aerosolization and/or aerial transport. Future work should further investigate how atmospheric chemicals and physics influence microbial survival and adaptation in order to be able to model the composition of planetary boundary layer microbial communities based on the surrounding landscapes and meteorology.