One of the paths of improving the food bio-safety of dairy products is preventing the development of pathogenic and putrefactive bacteria by creating competitive microbiological medium in the products. Beneficial microflora introduced can decrease the risk of developing spoilage microorganisms and also give functional characteristics to product. Streptococcus thermophilus is an essential lactic acid bacterium used for its high acidification ability, which includes the production of fermented milk products and cheese. The strain is considered Generally Recognized as safe by the US Food and Drug Administration (FDA) in the US. In Europe, Streptococcus thermophilus has been granted Qualified Presumption of Safety (QPS) status since 2007 by the European Food Safety Authority (EFSA) – a status granted on species level. This is one of the two dairy starters of yogurt and its recovery in faeces of human volunteers consuming yogurt has definitively established that this bacterium is capable to remain alive during its transit through the digestive tract. Due to antagonistic activity against pathogenic and putrefactive bacteria, Streptococcus thermophilus has a considerable interest as a potential protective food agent. Especially important is his antagonistic activity against Staphylococcus aureus, Escherichia coli, Salmonella, Bacillus cereus, Pseudomonas, Yersinia, Listeria. These microorganisms in small quantities in food products present a significant threat to food safety, and therefore to public health. The Streptococcus thermophilus strain used in the study was isolated from autochthonous spontaneously fermented milk and identified in Laboratory of Food Biotechnology (PSIHFT). The strain Streptococcus thermophilus ST-102 was cultivated at 40°C in the skim milk medium. Antimicrobial activity of ST-102 strain against pathogens was studied. Foodborne pathogens and spoilage microorganisms for testing antibacterial activity: Pseudomonas aeruginosa, Bacillus cereus, Staphylococcus aureus, Escherichia coli were received from National Center of Public Health (Republic of Moldova). During the experiment the change in cell number, the optical density and the acidity of the medium were evaluated. Also parameters indirectly characterizing the survival of the strain in the gastrointestinal tract were studied. The obtained Streptococcus thermophilus ST-102 strain possesses the basic cultural, morphological and technological characteristics for this species, capable of actively accumulating biomass. The number of cells of the strain reached about lg 9 CFU/cm3 less than 5 hours of growth, which is higher than the normal number of viable cells lg7 CFU/cm3 in functional dairy products. By changing the medium acidity, we can say that the strain has the typical dynamics of Streptococcus thermophilus lowering acidity. The number of cells in the medium at lg 9 CFU/cm3 and lowering pH environment of less than 5 units able to provide increasing food safety. Research has shown the pronounced manifestation at antagonistic activity of the studied strain in relation to the test cultures of E. coli and Staphylococcus aureus. Analysis of obtained data showed that the strain ST-102 is stable in a medium with the addition of NaCl at a concentration of 2%. Some strain cells population can survive in a medium supplemented with 20% of bile. These tests lead to the conclusion that Streptococcus thermophilus ST-102 possess sufficiently high tolerance to unfavorable factors, which arise in the gastrointestinal tract of the human body. Strain ST-102 can be characterized as a natural, safe, exhibits antagonistic activity toward pathogens. The obtained growth dynamics data expand the understanding of the cultivation process of the studied strain. Such information is valuable for higher quality biomass growth of studied strain in the laboratory and on an industrial scale.