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Contributors and Sponsors

Cloudy with a chance of microbes Lingering questions about the nature and role of microorganisms in the atmosphere Brent Christner Department of Biological Sciences, Louisiana State University xner@lsu.edu . Contributors and Sponsors. LSU students: Amanda Achberger W. Peyton Adkins

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Contributors and Sponsors

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  1. Cloudy with a chance of microbesLingering questions about the nature and roleof microorganisms in the atmosphere Brent ChristnerDepartment of Biological Sciences, Louisiana State University xner@lsu.edu Contributors and Sponsors LSU students: Amanda Achberger W. Peyton Adkins MeggieAlleman Allen Bordelon Bethany Broekhoven Noelle Bryan Scott Burke RongmanCai SahitiKilaru Other collaborators: Sumeet Dua (LA Tech) Christine Foreman (Montana State) Laurence Henry (Southern University) Cindy Morris (INRA, Montfavet, France) Vaughan Phillips (University of Hawaii) Fred Rainey (Univ. Alaska-Anchorage) David Sands (Montana State) David Schmale (Virginia Tech) Mark Skidmore (Montana State) LSU co-PIs and researchers: John Battista Brad Ellison Jim Giammanco T. Gregory Guzik Doug Granger Gary King Kevin McCarter Michael Stewart John Wefel

  2. Biological IN are the most active freeze catalysts in nature. • Mineral dusts are not active as IN > -15oC, yet many clouds warmer than this contain ice phase precipitation. • Biological IN may play a role in the processes leading to precipitation and Earth’s radiative balance. • What is the high altitude boundary for life on Earth? • Helium balloon payloads for the collection and microbial analysis of air samples from altitudes up to 38 km.

  3. Total oversimplification of the processes leading to precipitation Water vapor/droplets + ice nuclei + freezing temperature Ice nucleation: deposition, condensation, contact, or immersion freezing(particles initiate the freezing of water vapor or droplets to form ice particles) Ice crystal formation and growth (gain sufficient mass to overcome gravity and fall to the ground) Snowflake formation orice melts and hits the ground as rain

  4. Warmest temperature of activity for some ice nucleation-active materials † • † Temperatures are for the immersion mode of ice nucleation ¥ The temperature of ice nucleation activity in Ice+ strains • Christner (2010) ApplMicrobiol Biotech, 85:481-489

  5. Determining the activity, quantity, and nature of freeze immersion ice nuclei or nucleators (IN) e.g., ‘Untreated’ – ‘Lysozyme’ insensitive = # of bacterial IN A. Achberger (unpublished data)

  6. France Antarctica and Yukon Montana IN active at -7oC in freshly collected snow from Montana, France, Antarctica, and the Yukon Christner et al. (2008) Science, 319:1214; PNAS, 48:18854-18859 ~95% of the IN active at > -10oC in snow and rain are biological particles; at least 40% are bacterial in origin

  7. Is there a bioprecipitation cycle? Ice nucleation in clouds and enhanced precipitation Aerosolization of bacterial IN from the phylosphere Transfer of bacteria to new plant host Epiphytic bacterial growth Sands et al. (1982) J HungarianMeteorolServ 86:148-152; Morris et al. (2004) J Phys IV France, 121:87-103

  8. In situ detection of biological particlesin cloud ice-crystals (Pratt et al. 2009, Nature Geoscience, 2:398-401) • Sampled ice crystal residues while flying through clouds in the skies over Wyoming, USA. • Used aircraft-aerosol time-of-flight spectrometry to directly measure the chemistry of individual cloud ice-crystal residues. • Determined that ~50% of the ice-crystal residues were mineral dust; ~33% were biological particles. • First evidence for the involvement of biological particles (i.e., bacteria, fungi and/or plant material) in ice-cloud processes.

  9. 5 X 200 X 20 X 6 x108 km2 total leaf surface for terrestrial plants (1024 to 1026 cells)

  10. Do biological IN possess the exclusive role as natural atmospheric IN at temperatures above about -15oC? • Are their concentrations sufficient to trigger precipitation directly? • Are unidentified biological particles active IN at lower temperatures? • Are there large seasonal/regional variations of these types of IN? • Can their numbers be defined and can they be identified by source? Direct measurements of biological IN are lacking for the full temperature regime relevant to ice formation in mixed-phase clouds Demott and Prenni (2010)

  11. Sampling microbes in the lower atmosphere using aerial unmanned autonomous vehicles (UAVs) Above: A UAV fitted with 8 sampling surfaces that are shown in the open position. Sampling is controlled by remote control from the ground and it is possible to sample > 150,000 L of air during a single flight. Top right: Accurate sampling path (grey lines) of one of the UAVs flying around a single GPS waypoint (black dot) 100 m above the ground. Images and video: David Schmale (Virginia Tech)

  12. Aerobiological sampling using a latex sounding balloon platform • 3000 g latex sounding balloon • Parachute • Cut down apparatus • Primary beacon • CW Morse Beacon • Secondary Beacon • Microbiological sampling payloads A sounding balloon with < 5.4 kg of total payload is a low cost and logistically feasible approach to conduct microbiological sampling at altitudes in the troposphere and stratosphere. Video: HABITAT-1, July 2009; Image: HABITAT-5, June 2010

  13. Long duration sampling at 38 km with the High Altitude Student Payload (HASP) 100 km

  14. 10 mm

  15. Determining the limits for microbial survival in the high atmosphere will… • yield data to assess the geographic boundaries for microbial dispersal via the atmosphere on a global scale. • reveal the properties of microbes surviving extremes of low pressure, temperature, and relative humidity and high fluence rates of UV. • provide information that can be applied to assess the habitability of other planetary environments. At an altitude of 30 km, the pressure, temperature, and radiation levels are similar to the surface of Mars. ≈ MARSLIFE: Modes of Adaptation, Resistance, and Survival for Life Inhabiting a Freeze-dried-radiation-bathed Environment (2010 NASA / LA BOR grant) 

  16. “If I could have sampled at 1000 m above the ground with a balloon, the air would have been perfectly sterile.” Louis Pasteur (circa 1860) Altitude (mi) Altitude (km) † Weight equivalent of 4 to 40 blue whales

  17. Summary • Affect of biological IN on climate? A game of numbers. • The role of biological IN in precipitation generation could be most relevant in clouds at temperatures > -15oC. • Collaborative research needed between atmospheric scientists and microbiologists to quantify and characterize the ecological sources and meteorological role of biological IN. • Species with characteristics (e.g., resistance to desiccation, cold, and UV/ionizing radiation) that provide a selective advantage in the atmosphere are relevant to astrobiology. • The high altitude limits for life on Earth will provide information to assess the habitability of other planetary environments.

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