Airborne Bacteria in Earth's Lower Stratosphere Resemble Taxa Detected in the Troposphere: Results From a New NASA Aircraft Bioaerosol Collector (ABC)

Authors

David J. Smith, NASA Ames Research Center
Jayamary D. Ravichandar, Second Genome Inc.
Sunit Jain, Second Genome Inc.
Dale W. Griffin, USGS Environmental Health
Hongbin Yu, NASA Goddard Space Flight Center
Qian Tan, Bay Area Research Institute, Moffett Field
James Thissen, Lawrence Livermore National Laboratory
Terry Lusby, NASA Ames Research Center
Patrick Nicoll, Blue Marble Space Institute of Science, Moffett Field
Sarah Shedler, University of South FloridaFollow

Document Type

Article

Publication Date

8-2018

Keywords

bioaerosols, bacteria, C-20A, troposphere, stratosphere, Aircraft Bioaerosol Collector (ABC)

Digital Object Identifier (DOI)

https://doi.org/10.3389/fmicb.2018.01752

Abstract

Airborne microorganisms in the upper troposphere and lower stratosphere remain elusive due to a lack of reliable sample collection systems. To address this problem, we designed, installed, and flight-validated a novel Aircraft Bioaerosol Collector (ABC) for NASA's C-20A that can make collections for microbiological research investigations up to altitudes of 13.7 km. Herein we report results from the first set of science flights—four consecutive missions flown over the United States (US) from 30 October to 2 November, 2017. To ascertain how the concentration of airborne bacteria changed across the tropopause, we collected air during aircraft Ascent/Descent (0.3 to 11 km), as well as sustained Cruise altitudes in the lower stratosphere (~12 km). Bioaerosols were captured on DNA-treated gelatinous filters inside a cascade air sampler, then analyzed with molecular and culture-based characterization. Several viable bacterial isolates were recovered from flight altitudes, including Bacillus sp., Micrococcus sp., Arthrobacter sp., and Staphylococcus sp. from Cruise samples and Brachybacterium sp. from Ascent/Descent samples. Using 16S V4 sequencing methods for a culture-independent analysis of bacteria, the average number of total OTUs was 305 for Cruise samples and 276 for Ascent/Descent samples. Some taxa were more abundant in the flight samples than the ground samples, including OTUs from families Lachnospiraceae, Ruminococcaceae and Erysipelotrichaceae as well as the following genera: Clostridium, Mogibacterium, Corynebacterium, Bacteroides, Prevotella, Pseudomonas, and Parabacteroides. Surprisingly, our results revealed a homogeneous distribution of bacteria in the atmosphere up to 12 km. The observation could be due to atmospheric conditions producing similar background aerosols across the western US, as suggested by modeled back trajectories and satellite measurements. However, the influence of aircraft-associated bacterial contaminants could not be fully eliminated and that background signal was reported throughout our dataset. Considering the tremendous engineering challenge of collecting biomass at extreme altitudes where contamination from flight hardware remains an ever-present issue, we note the utility of using the stratosphere as a proving ground for planned life detection missions across the solar system.

Comments

Complete list of authors: Paul Martinez, Alejandro Osorio, Jason Lechniak, Samuel Choi, Kayleen Sabino, Kathryn Iverson, Luisa Chan, Crystal Jaing, John McGrath

Rights Information

This work is licensed under a Creative Commons Attribution 4.0 License.

Was this content written or created while at USF?

Yes

Citation / Publisher Attribution

Frontiers in Microbiology, v. 9, art. 1752

Scholar Commons Citation

Smith, David J.; Ravichandar, Jayamary D.; Jain, Sunit; Griffin, Dale W.; Yu, Hongbin; Tan, Qian; Thissen, James; Lusby, Terry; Nicoll, Patrick; and Shedler, Sarah, "Airborne Bacteria in Earth's Lower Stratosphere Resemble Taxa Detected in the Troposphere: Results From a New NASA Aircraft Bioaerosol Collector (ABC)" (2018). Marine Science Faculty Publications. 1290.
https://digitalcommons.usf.edu/msc_facpub/1290