The study of the acid stress of the propionic acid bacteria

The article presents the results of the stability studying of propionic acid bacteria to acid stress. The object of the research is chosen due to the ^ fact that propionic acid bacteria and probiotics are considered as promising and their positive influence on human health is generally accepted. They inhibit the activity of pathogenic microorganisms, form B vitamins and a large amount of vitamin B 12, have antimutagenic properties, will provide protection against intestinal infections, some strains cause inhibition of growth of cancer cells. It was found that a propionic acid bacteria P. freundenreichii subsp. freudenreichii 216 B-2 has the most highly resistance to acid stress. The survival rate of this strain after 1.5 hours of incubation at pH 2 is 64%, and the least resistant strain of P. freudenreichii subsp. shermanii AC-2503 - 36%. High viability of propionic acid bacteria at low pH is due to antioxidant defense system, which is characterized by the reaction of tolerance to acid, which gives them increased survival with low acidity.