Journal Article

Microbiome of the upper troposphere: Species composition and prevalence, effects of tropical storms, and atmospheric implications

Lathem, Terry L., Nenes, Athanasios, DeLeon-Rodriguez, Natasha, Ziemba, Luke D., Beyersdorf, Andreas J., Anderson, Bruce E., Konstantinidis, Konstantinos T., Rodriguez-R, Luis M., Barazesh, James M., Bergin, Michael

2013

Overview

The composition and prevalence of microorganisms in the middle-to-upper troposphere (8–15 km altitude) and their role in aerosol-cloud-precipitation interactions represent important, unresolved questions for biological and atmospheric science. In particular, airborne microorganisms above the oceans remain essentially uncharacterized, as most work to date is restricted to samples taken near the Earth’s surface. Here we report on the microbiome of low- and high-altitude air masses sampled onboard the National Aeronautics and Space Administration DC-8 platform during the 2010 Genesis and Rapid Intensification Processes campaign in the Caribbean Sea. The samples were collected in cloudy and cloud-free air masses before, during, and after two major tropical hurricanes, Earl and Karl. Quantitative PCR and microscopy revealed that viable bacterial cells represented on average around 20% of the total particles in the 0.25- to 1-μm diameter range and were at least an order of magnitude more abundant than fungal cells, suggesting that bacteria represent an important and underestimated fraction of micrometer-sized atmospheric aerosols. The samples from the two hurricanes were characterized by significantly different bacterial communities, revealing that hurricanes aerosolize a large amount of new cells. Nonetheless, 17 bacterial taxa, including taxa that are known to use C1–C4 carbon compounds present in the atmosphere, were found in all samples, indicating that these organisms possess traits that allow survival in the troposphere. The findings presented here suggest that the microbiome is a dynamic and underappreciated aspect of the upper troposphere with potentially important impacts on the hydrological cycle, clouds, and climate.

• Publisher: National Academy of Sciences,National Acad Sciences
• Subject: Aerosols / air / Air masses / Air Microbiology / Air sampling / Airborne microorganisms / Altitude / Analysis of Variance / Animal, plant and microbial ecology / Atmosphere / Atmospheric aerosols / Atmospheric sciences / Atmospherics / Bacteria / bacterial communities / Biodiversity / Biological and medical sciences / Biological Sciences / carbon / Caribbean Region / Caribbean Sea / Cells / climate / Clouds / Cyclonic Storms / Fundamental and applied biological sciences. Psychology / fungi / High altitude / Hurricanes / Hydrologic cycle / Metagenome - genetics / Microbial ecology / microbiome / Microorganisms / microscopy / National Aeronautics and Space Administration / Oceans / Phylogeography / Polymerase chain reaction / Precipitation / quantitative polymerase chain reaction / rRNA genes / Sequence Analysis, DNA / Species composition / species diversity / Species Specificity / Taxa / Troposphere / Various environments (extraatmospheric space, air, water)