1. a Laboratory of Bioactive Polymers, Institute of Polymers, Bulgarian Academy of Sciences, Acad. G. Bonchev 103A, 1113 Sofia, Bulgaria
2. b Institute of Microbiology, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
3. c Laboratory of Bioactive Polymers, Institute of Polymers, Bulgarian Academy of Sciences, Acad. G. Bonchev 103A, 1113 Sofia, Bulgaria
4. d Laboratory of Bioactive Polymers, Institute of Polymers, Bulgarian Academy of Sciences, Acad. G. Bonchev 103A, 1113 Sofia, Bulgaria