Particle Size Distribution of Airborne Microorganisms and Pathogens during an Intense African Dust Event in the Eastern Mediterranean

• Published in: Environmental health perspectives Vol. 116; no. 3; pp. 292 - 296
• Main Authors: Polymenakou, Paraskevi N., Mandalakis, Manolis, Stephanou, Euripides G., Tselepides, Anastasios
• Format: Journal Article
• Language: English
• Published: United States National Institute of Environmental Health Sciences. National Institutes of Health. Department of Health, Education and Welfare 01.03.2008; National Institute of Environmental Health Sciences
• Subjects: Abundance; Actinobacteria; Aerosols; Africa, Northern; Air Movements; Air Pollutants - analysis; Airborne microorganisms; Bacteria; Bacteria - classification; Bacteria - genetics; Bacteria - isolation & purification; Bacterial Infections - microbiology; Bacterial Infections - prevention & control; Bacterial Infections - transmission; Dust; Dust - analysis; Dust storms; Environmental Monitoring; Greece; Health aspects; Humans; Libraries; Marine ecosystems; Microorganisms; Particle Size; Particle size classes; Particle size distribution; Pathogenic microorganisms; Pathogens; Phylogenetics; Polymerase chain reaction; RNA, Bacterial - genetics; RNA, Ribosomal, 16S - genetics; Africa, Northern; Greece; MED, Eastern Mediterranean; microbial transport; pathogens; particle size distribution; bacterial community composition; African dust
• ISSN: 0091-6765; 1552-9924
• DOI: 10.1289/ehp.10684

Background: The distribution of microorganisms, and especially pathogens, over airborne particles of different sizes has been ignored to a large extent, but it could have significant implications regarding the dispersion of these microorganisms across the planet, thus affecting human health. Objectives: We examined the microbial quality of the aerosols over the eastern Mediterranean region during an African storm to determine the size distribution of microorganisms in the air. Methods: We used a five-stage cascade impactor for bioaerosol collection in a coastal city on the eastern Mediterranean Sea during a north African dust storm. Bacterial communities associated with aerosol particles of six different size ranges were characterized following molecular culture-independent methods, regardless of the cell culturability (analysis of 16S rRNA genes). Results: All 16S rDNA clone libraries were diverse, including sequences commonly found in soil and marine ecosystems. Spore-forming bacteria such as Firmicutes dominated large particle sizes (> 3.3 micrometers), whereas clones affiliated with Actinobacteria (found commonly in soil) and Bacteroidetes (widely distributed in the environment) gradually increased their abundance in aerosol particles of reduced size (< 3.3 micrometers). A large portion of the clones detected at respiratory particle sizes (< 3.3 micrometers) were phylogenetic neighbors to human pathogens that have been linked to several diseases. Conclusions: The presence of aerosolized bacteria in small size particles may have significant implications to human health via intercontinental transportation of pathogens.