EMBARGOED UNTIL: Tuesday 5/21, 3 PM MDT
(Symposium Session 221)
Natasha De Leon-Rodriguez
School of Biology, Georgia Institute of Technology
Atlanta, GA, United States
Phone: 787 368-6265
Whether the microorganisms routinely inhabit the upper troposphere – perhaps living on carbon compounds also found there – or whether they were simply lofted there from the Earth’s surface isn’t yet known. Airborne microbes are of interest to atmospheric scientists, because they could play a role in forming ice that may impact weather and climate, and long-distance transport of the bacteria could also be of interest for disease transmission models.
Microorganisms present in the atmosphere were documented in air samples taken as part of NASA’s Genesis and Rapid Intensification Processes (GRIP) program to study low- and high-altitude air masses associated with hurricanes. The sampling was done onboard a specialized DC-8 aircraft over both land and ocean, including the Caribbean Sea and portions of the Atlantic Ocean. The sampling took place before, during and after two major tropical hurricanes – Earl and Karl – in 2010.
When the air masses sampled originated over the ocean, the sampling found mostly marine bacteria. Air masses that originated over land had mostly terrestrial bacteria. The hurricanes had also a strong effect on the distribution and composition of microorganisms, aerosolizing a lot of new cells. Perhaps most importantly, our analyses showed that microbial cells present in the upper troposphere represent an important fraction of the total particles present, which could have important implications for climate modeling. Therefore, the work that we will present during the General American Society of Microbiology aims to characterize the bacteria present at different altitudes in the troposphere using community DNA sequencing (a.k.a metagenomics). More specifically, we investigated the genetic mechanisms by which microbial cells could reach and remain at high altitudes in the atmosphere and initiate the formation of water droplets or ice crystals, which is important for cloud formation. The known proteins (i.e., inaZ) that can initiate ice crystals were not found at high altitude samples, but genes related to oxidative stress, UV resistance, and oxalate oxidation were overrepresented in atmospheric samples relative to those from habitats on Earth.
The research team included Natasha DeLeon-Rodriguez and Luis-Miguel Rodriguez-R from the School of Biology, Terry Lathem and Prof. Athanasios Nenes from the School of Earth and Atmospheric Sciences, and James Barazesh, Prof. Michael Bergin and Prof. Kostas Konstantinidis from the School of Civil and Environmental Engineering at Georgia Tech. It also included NASA scientists Dr. Bruce Anderson, Dr. Andreas Beyersdorf, and Dr. Luke Ziemba with the Chemistry and Dynamics Branch/Science Directorate at the NASA Langley Research Center in Hampton, Virginia. This research was supported, in part, by NASA grant number NNX10AM63G, by a GAANN Fellowship from the U.S. Department of Education, a NASA-NESSF fellowship, and by a National Science Foundation (NSF) graduate research fellowship. Some results from this study were published earlier this year, DeLeon-Rodriguez et al., PNAS 2013.