RP 9: Screening and characterization of biological ice nuclei and their influence on the ice nucleation activity of soil dust

Dr. J. Fröhlich
Multiphase Chemistry Department, Max Planck Institute for Chemistry, Mainz

PD Dr. Ulrich Pöschl

Multiphase Chemistry Department, Max Planck Institute for Chemistry, Mainz

 

Assistance:  Dr. Bernhard G. Pummer (Post-Doc), Dr. Martin Linden (Post-Doc), Dr. Jan Frederik Scheel (Post-Doc), Petya Yordanova (master student), Anna T. Kunert (PhD student)

 

 

Primary biological aerosol particles are ubiquitous in the atmosphere as air is one of the main media for the dispersal of microorganisms and pollen and connects all ecosystems at the Earth’s surface. The abundance, diversity, sources, seasonality, biogeographic distribution, and effects of biological aerosol particles in the atmosphere are hardly known although the potential role of biological particles in triggering glaciation and precipitation has recently been supported. The best known biological ice nucleators are species of common plant-associated bacteria but only a few fungal species are reported being ice nucleation active.

 

Thus, RP9 in INUIT-1 was focused on:

  • the characterization of the overall abundance and diversity of primary biological aerosol particles by DNA-analysis
  • investigating the ice nucleation activity of fungi that are abundant in the atmosphere
  • the identification of unknown ice nucleating (IN) fungi in atmospheric aerosol and soil
  • samples and unraveling of the structures of the responsible molecules

 

To summarize INUIT Phase 1, there is a high diversity of fungi in the atmosphere but only a few fungal species have so far been reported as being ice nucleation active. Our investigations of soil and air shows that more ice nucleation active fungal species are out there and that the ice nucleation activity is not restricted to fungal spores. Microbial cell-free ice nucleation active macromolecules (INM) released from soil and airborne fungi might contribute to the as yet unknown pool of atmospheric ice nucleation active particles. We think, that the number of IN microorganisms is likely to rise significantly when systematic surveys by soil, cryptogamic cover or phylloplane fungi and other microorganisms would be undertaken.

 

Thus, the second phase is aimed at identifying unknown IN organisms and materials from soils, plants, and cryptogamic covers and on the investigation of their influence on the ice nucleating activity of soil and mineral dust. As the atmospheric importance of IN fungi, either directly or indirectly via their cell-free INM, depends not only on their relative contribution to the INM in soil dust, but also on their number concentrations at cloud altitudes, further investigations are planned for the identification of INM and the quantification of these fungi and their INM in atmospheric samples.

 

The specific objectives of Phase 2 are:

  • Identification of different types and species of biological ice nucleators (e.g. cryptogamic soil and plant covers, cyanobacteria, fungi etc.) by screening of culture collection organisms and environmental samples
  • Characterization and identification of the INM and corresponding genes
  • Determination of the influence of these INM on the ice nucleation properties on soil and mineral dust

 

 

More information about this project http://www.mpic.de/forschung/multiphasenchemie/group-froehlich.html