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

Frontiers in Microbiology

Samuel Choi¹  Alejandro Osorio¹  Sarah Shedler²  Hongbin Yu³  Qian Tan⁴  James Thissen⁵  Crystal Jaing⁵  David J. Smith⁶  Terry Lusby⁶  Paul Martinez⁷  Jason Lechniak⁷  John McGrath⁷  Luisa Chan⁸  Kathryn Iverson⁸  Kayleen Sabino⁸  Sunit Jain⁸  Jayamary Divya Ravichandar⁸  Patrick Nicoll⁹  Dale W. Griffin^1,10 

[1] 0Jacobs Technology Inc., NASA Armstrong Flight Research CenterPalmdale, CA, United States;Biological Oceanography Department, University of South Florida, College of Marine SciencesSt. Petersburg, FL, United States;Climate and Radiation Laboratory, NASA Goddard Space Flight CenterGreenbelt, MD, United States;Earth Science Division, Bay Area Environmental Research InstituteMoffett Field, CA, United States;Lawrence Livermore National LaboratoryLivermore, CA, United States;NASA Ames Research Center, Space Biosciences DivisionMoffett Field, CA, United States;NASA Armstrong Flight Research CenterPalmdale, CA, United States;Second Genome Inc.South San Francisco, CA, United States;Space Biosciences Division, Blue Marble Space Institute of ScienceMoffett Field, CA, United States;United States Geological Survey, Environmental HealthSt. Petersburg, FL, United States;

关键词: bioaerosols;    bacteria;    C-20A;    troposphere;    stratosphere;    Aircraft Bioaerosol Collector (ABC);   

DOI  :  10.3389/fmicb.2018.01752

来源: DOAJ

【 摘 要 】

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.

【 授权许可】

Unknown