Particle size distribution of airborne microorganisms and pathogens during an Intense African dust event in the eastern Mediterranean.
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.


OBJECTIVE
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 microm), 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 microm). A large portion of the clones detected at respiratory particle sizes (< 3.3 microm) 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.
Polymenakou
Paraskevi N
PN
Hellenic Centre for Marine Research-Crete, Heraklion, Greece. polymen@her.hcmr.gr
Mandalakis
Manolis
M
Stephanou
Euripides G
EG
Tselepides
Anastasios
A
D000352:Africa, Northern; D000392:Air Movements; D000393:Air Pollutants / Q000032:analysis*; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D001424:Bacterial Infections / Q000382:microbiology / Q000517:prevention & control / Q000635:transmission; D004391:Dust / Q000032:analysis*; D004784:Environmental Monitoring; D006115:Greece; D006801:Humans; D010316:Particle Size; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics
D000393:Air Pollutants; D004391:Dust; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S