Abstract
We characterized the composition, diversity, and potential bacterial aerosol sources in Athens’ urban air by DNA barcoding (analysis of 16S rRNA genes) during three seasons in 2019. Air samples were collected using the recently developed Rutgers Electrostatic Passive Sampler (REPS). It is the first field application of REPS to study bacterial aerosol diversity. REPS samplers captured a sufficient amount of biological material to demonstrate the diversity of airborne bacteria and their variability over time. Overall, in the air of Athens, we detected 793 operational taxonomic units (OTUs), which were fully classified into the six distinct taxonomic categories (Phylum, Class, Order, etc.). These OTUs belonged to Phyla Actinobacteria, Firmicutes, Proteobacteria, Bacteroidetes, Cyanobacteria, and Fusobacteria. We found a complex community of bacterial aerosols with several opportunistic or potential pathogens in Athens’ urban air. Referring to the available literature, we discuss the likely sources of observed airborne bacteria, including soil, plants, animals, and humans. Our results on bacterial diversity are comparable to earlier studies, even though the sampling sites are different or geographically distant. However, the exact functional and ecological role of bioaerosols and, even more importantly, their impact on public health and the ecosystem requires further air monitoring and analysis.
Highlights
Bioaerosols are airborne particles of biological origin, including pathogenic and nonpathogenic, viable and nonviable, culturable and nonculturable microorganisms, and their products, high molecular weight allergens, as well as pollen
Over the past few years, bioaerosol science has evolved into a multidisciplinary field with contributions and interest from aerosol science, biology, toxicology, ecology, plant and animal pathology, microbiology, air quality, public health, and meteorology
High relative humidity and rain have been negatively associated with bacterial diversity, since moisture intensifies their deposition by increasing particle sizes, and wet soil surfaces make aerosolization less likely [9]
Summary
Bioaerosols are airborne particles of biological origin, including pathogenic and nonpathogenic, viable and nonviable, culturable and nonculturable microorganisms, and their products (e.g., toxins, cysts, or fragments), high molecular weight allergens, as well as pollen. Bioaerosols play a vital role in the Earth’s ecosystem, in the interactions between the atmosphere, biosphere, climate, and public health. Over the past few years, bioaerosol science has evolved into a multidisciplinary field with contributions and interest from aerosol science, biology, toxicology, ecology, plant and animal pathology, microbiology, air quality, public health, and meteorology. Despite the importance of bioaerosols, their sources, abundance, diversity, and interactions within the atmospheric microbiome are not yet sufficiently well characterized and understood. Bioaerosol release and dispersion from environmental sources are often facilitated by meteorological processes, such as buoyant air masses created by solar heat or wind shear. Meteorological conditions (e.g., wind speed, relative humidity, temperature, and solar radiation) and physicochemical factors affect the diversity and dispersion of airborne microbial communities [6,7,8]. High relative humidity and rain have been negatively associated with bacterial diversity, since moisture intensifies their deposition by increasing particle sizes, and wet soil surfaces make aerosolization less likely [9]
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