AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Interactions of Airborne Microbial Communities with Clouds: A Perpective from Metagenomic Analysis
NATASHA DELEON-RODRIGUEZ, Terry Lathem, Bruce Anderson, Andreas Beyersdorf, Luke Ziemba, Michael Bergin, Athanasios Nenes, Kostantinos Kostantinidis, Georgia Institute of Technology, Atlanta, GA
Abstract Number: 527 Working Group: Bioaerosols: Characterization and Environmental Impact
Abstract Microbial cells are thought capable of influencing cloud formation and precipitation. Their small size and membrane composition allow them to have higher atmospheric residence time. Several species of bacteria are good ice nucleators, owing to the presence of an outer-membrane protein that serves as a nucleation center. The impact of bacterial cells on cloud formation however remains poorly characterized. Most studies to date were conducted on Earth surface (high mountains) and assessed only the small subunit ribosomal rRNA gene; microbial communities at higher altitudes remain essentially uncharacterized. To study the bacterial communities in the upper and lower troposphere, samples from high altitudes (over 10km) and two major tropical hurricanes were collected on board the DC3 aircraft during the NASA Genesis and Rapid Intensification Processes campaign and samples from low altitudes on board the P3B aircraft during the NASA Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality campaign. Metagenomic sequencing was performed for four samples, three high altitudes and one low altitude using Ilumina-GAII sequencing technology. Taxonomic analysis showed that Proteobacteria is the most abundant phylum in the atmosphere, but that Bacteroidetes and Actinobacteria are the second most abundant in the high and low altitude samples, respectively. To understand how bacterial cells may influence cloud formation, the inaZ gene was search in all metagenomes. We found the presence of this gene in the low altitude sample. This result was consistent with the present of Pseudomonas, which account for approximately 5% of the total community of this sample. Pseudomonas sp. are known to be one of the best ice nucleation in the atmosphere. Metagenomic analysis of bacterial communities in the atmosphere would provide quantitative insights in the distribution of proteins related to cloud formation and cloud chemistry.