1. The Stephan Angeloff Institute of Microbiology, Bulgarian Academy of Sciences, 26 Georgi Bonchev Str., 1113 Sofia, Bulgaria
2. Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, 25 Georgi Bonchev Str., 1113 Sofia, Bulgaria
3. Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, 23 Georgi Bonchev Str., 1113 Sofia, Bulgaria