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Applied and Environmental Microbiology, August 2009, p. 5121-5130, Vol. 75, No. 15
0099-2240/09/$08.00+0 doi:10.1128/AEM.00447-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
Characterization of Airborne Microbial Communities at a High-Elevation Site and Their Potential To Act as Atmospheric Ice Nuclei
Robert M. Bowers,1*
Christian L. Lauber,2
Christine Wiedinmyer,3
Micah Hamady,4
Anna G. Hallar,5
Ray Fall,2,6
Rob Knight,6 and
Noah Fierer1,2
Department of Ecology and Evolutionary Biology, UCB 334, University of Colorado, Boulder, Colorado 80309,1 Cooperative Institute for Research in Environmental Sciences, UCB 216, University of Colorado, Boulder, Colorado 80309,2 National Center for Atmospheric Research, Boulder, Colorado 80301,3 Department of Computer Science, UCB 430, University of Colorado, Boulder, Colorado,4 Desert Research Institute, Storm Peak Laboratory, 2215 Raggio Parkway, Reno, Nevada 89512,5 Department of Chemistry and Biochemistry, UCB 215, University of Colorado, Boulder, Colorado 803096
Received 23 February 2009/ Accepted 2 June 2009
Bacteria and fungi are ubiquitous in the atmosphere. The diversity and abundance of airborne microbes may be strongly influenced by atmospheric conditions or even influence atmospheric conditions themselves by acting as ice nucleators. However, few comprehensive studies have described the diversity and dynamics of airborne bacteria and fungi based on culture-independent techniques. We document atmospheric microbial abundance, community composition, and ice nucleation at a high-elevation site in northwestern Colorado. We used a standard small-subunit rRNA gene Sanger sequencing approach for total microbial community analysis and a bacteria-specific 16S rRNA bar-coded pyrosequencing approach (4,864 sequences total). During the 2-week collection period, total microbial abundances were relatively constant, ranging from 9.6 x 105 to 6.6 x 106 cells m–3 of air, and the diversity and composition of the airborne microbial communities were also relatively static. Bacteria and fungi were nearly equivalent, and members of the proteobacterial groups Burkholderiales and Moraxellaceae (particularly the genus Psychrobacter) were dominant. These taxa were not always the most abundant in freshly fallen snow samples collected at this site. Although there was minimal variability in microbial abundances and composition within the atmosphere, the number of biological ice nuclei increased significantly during periods of high relative humidity. However, these changes in ice nuclei numbers were not associated with changes in the relative abundances of the most commonly studied ice-nucleating bacteria.
* Corresponding author. Mailing address: University of Colorado at Boulder, UCB 216, Boulder, CO 80309-0216. Phone: (303) 492-2099. Fax: (303) 492-1149. E-mail: robert.bowers{at}colorado.edu
Published ahead of print on 5 June 2009.
Applied and Environmental Microbiology, August 2009, p. 5121-5130, Vol. 75, No. 15
0099-2240/09/$08.00+0 doi:10.1128/AEM.00447-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
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