1. University of Salzburg, Division of Molecular Biology, Department of Microbiology, Salzburg, Austria.
2. Research Group for Biophysics, Hungarian Academy of Sciences, Budapest, Hungary.
3. Space Research Institute of the Austrian Academy of Sciences, Graz, Austria.
4. University of Salzburg, Division of Materials Engineering and Physics, Department of Physics and Biophysics, Salzburg, Austria.
5. On leave from the Space Research Institute of the Austrian Academy of Sciences, Graz, Austria.