T. Dinev1*, G. Beev1, S. Denev1, D. Dermendzhieva2, M. Tzanova1, E. Valkova1 1Department of Biochemistry, Microbiology and Physics, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria 2Department of Applied Ecology and Animal Hygiene, Faculty of Agriculture, Trakia