The disclosure refers to novel strain of Lactobacillus delbrueckii ssp. bulgaricus (Selur 19) isolated from traditional yoghurt, produced in Bulgarian mountains - Stara Planina and Rodopi and the use of this novel strain in combination with probiotic strain Lactobacillus gasseri K7 isolated from faeces of breast fed baby and/or Streptococcus thermophilus Selur 12 isolated from traditional yoghurt, produced in Bulgarian mountain - Stara Planina for the preparation of a food or feed probiotic supplements. Also, this invention relates to a prophylactic and therapeutic preparations comprising, as an effective component, different combinations of above mentioned strains and biogenics originating during fermentation of milk or whey, for maintaining the host's general health and preventing and/or treating gastrointestinal diseases. Further disclosed are procedures for preparing probiotic starter culture, probiotic Bulgarian yoghurt and probiotic food supplements based on milk or whey fermentation by above mentioned strains.
