RESISTANCE OF LACTOBACILLI STRAINS ISOLATED FROM DIFFERENT SOURCE TO SOME AGGRESSIVE FACTORS OF THE DIGITAL TRACT

Abstract

Aim. To study the resistance of lactobacilli strains to some aggressive factors of gastrointestinal tract in vitro depending on the primary isolation source. Methods. 13 lactobacilli strains isolated from self-fermenting vegetables, meat raw materials, children excrements were used in this work. The stability of bacteria to metabolites of the digestive system was determined by their cultivation in the MRS medium with bile, sodium chloride and phenol. Results. The vast majority of lactobacilli was tolerant at 2.5–5.0% NaCl. The increasing NaCl concentration to 7.5% has resulted in decrease of the viable cells number and its growth intensity. It was shown that the strains isolated from self-fermenting vegetables were the most resistant to NaCl. The presence of 20 and 40 % bile in the cultural medium slowed but did not inhibit the lactobacilli growth. The most resistant to bile were the strains isolated from raw meat. All lactobacilli strains grew in the presence of phenol in cultivation medium at concentrations of 0.2–0.6%, but it was shown that with increasing of phenol concentration, the optical density was significantly reduced. Conclusion. Investigated lactobacilli strains showed a variable reaction to the action of sodium chloride, salts of bile and phenol, which was determined by the specific strain and the concentration of the active substance. It has been shown that there is the partial relationship between resistance to the investigated factors and the source of lactobacilli isolation.