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There is a need to expand our knowledge of the diversity and biogeography of airborne microorganisms, since air connects all ecosystems at the Earth's surface. One of the most important phenomenon which can illustrate the role of the atmosphere as a dispersal mechanism for particulate matter is dust storms, that happen when the top soils from large deserts become airborne, and they can travel great distances through the atmosphere (Goudie and Middleton, 2001). More than half of the dust being transported in the atmosphere is believed to have originated from the Sahara-Sahel region in Africa (Kellog and Griffin, 2006). These dust storms are carrying microorganisms, some of them pathogens, along with the mineral particles (Griffin, 2007). Studies have shown that the global microbial taxa are not homogeneously distributed in the air, and the regional differences and how they come to be needs to be further understood (Fröhlich-Nowoisky et al, 2011). It has been shown that atmospheric transport leads to efficient exchange of species among different ecosystems (Burrows et al, 2009a/b). In order to better understand the relationship between microorganism transport and dust, the present study aims to seek for a rhythm in the airborne contents found in African dust events. Samples were collected between January 2011 and January 2012 in the Santiago Island from the Cape Verde archipelago. The sampling was done with a Hi-Vol with a PM10 head inlet (flow rate of 1,13 m3min-1). The sampling period was dictated by the data given by a continuous dust analyser (Grimm size dust analyser with 18 channels), with sampling periods ranging from less than 24 hours to 3 days. Deoxyribonucleic acid (DNA) of filter sample aliquots were extracted, amplified and cloned according to protocol already established (Fröhlich-Nowoisky et al, 2009). The DNA extracts were used in several polymerase chain reaction (PCR) runs, using primer pairs targeting fungi and Archaea. For some samples, the colony PCR was followed by restriction fragment length polymorphism (RFLP) analysis to observe diversity in the clones. Selected positive products from the colony PCR were then sent to for sequencing, and the obtained DNA sequences were blasted in the National Center for Biotechnology Information (NCBI) database for taxonomic attribution to different phyla, classes, and species (Després et al, 2007, Fröhlich-Nowoisky et al, 2009). Preliminary results for Archaea show a high diversity and the presence of members from the Crenoarcheaota, Thaumarchaeota and Euryarchaeota. It is also worth mentioning the finding of archeon clones belonging to the Halobacteria. As for the fungi, members of the Agaricomycetes are predominant for the Basidiomycota, with Dothideomycetes and Sordariomycetes appearing more often for the Ascomycota. Further results will be obtained from sequences that are still being analysed, as well as new samples that will be processed, to expand the present data set. Thanks for collaboration and support to M.O. Andreae, D. Jacob, N. Knothe, I. Müller, T. Pooya, the Max Planck Society (MPG), the LEC Geocycles in Mainz funded by the state Rheinland-Pfalz and the Portuguese Science Foundation through the project PTDD/AAC-CLI/100331/2008 (CV-Dust). J. Cardoso acknowledges the PhD grant SFRH-BD-6105-2009 from FCT. Burrows, S.M., Butler, T., Jöckel, P., Tost, H., Kerkweg, A., Pöschl, U. & Lawrence, M.G. (2009a) Atmos. Chem. Phys. 9, (23), 9281-9297. Burrows, S.M., Elbert, W., Lawrence, M.G. & Pöschl, U. (2009b). Atmos. Chem. Phys. 9, (23), 9263-9280. Després, V.R., Nowoisky, J.F., Klose, M., Conrad, R., Andreae, M.O., & Pöschl, U. (2007) Biogeosciences, 4, 1127-1141. Fröhlich-Nowoisky, J., Pickersgill, D.A., Després, V.R., & Pöschl U. (2009) Proc. Natl Acad. Sci. 106, 12814-12819. Fröhlich-Nowoisky, J., et al (2011) Biogeosciences Discuss. 8, 7071-7096. Goudie, A.S. and Middleton, N.J. (2001) Earth-Sci Rev 56 (1-4), 179-204 Griffin, D.W. (2007) Clin. Microbiol. Rev. 20 (3), 459-477 Kellog, C.A. and Griffin D.W. (2006) Trends Ecol Evol 21 (11), 638-644 |
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