ANTAGONISTIC ACTIVITY OF IMMOBILIZED PROBIOTICS STORED AT LOW TEMPERATURES

The results presented in this article contribute to the research devoted to the development of technologies for the long-term storage of probiotic cells immobilized in gel carriers. The purpose of this study is to investigate the antagonistic activity of probiotic strains of microorganisms immobilized in alginate gel without additives and with the addition of cryoprotective components after the storage at different low temperatures. Objects and methods. Probiotic strains of Escherichia coli M-17 (E. coli M-17), Lactobacillus acidophilus IMB B-2637 (L. acidophilus), Saccharomyces cerevisiae IMB Y-505 (S. cerevisiae) were immobilized in granules of 1% alginate gel without additives and with the addition of lactose (10%), sucrose (10%), LSM protective medium (final concentration in the gel of lactose was 1%, sucrose 5%, skimmed milk 5% v/v). To temperatures of -20, -40, -75°C, the sample freezing was performed at -20, -40, -75°C in freezing cabinets. The samples kept at -196°C, were first cooled to -40°C at a rate of 1 deg/min, and then transferred into liquid nitrogen. The samples were stored at this temperature regimen for 24 months. The samples were allowed to thaw in a water bath at 30°C. The granules were dissolved in a 4% EDTA solution. Cell viability was determined by the Koch "cup" method according to the ability to colony formation. The antagonistic activity of E. coli M-17 and L. acidophilus against test strains of bacteria was studied by the method of delayed antagonism. The antagonistic activity of S. cerevisiae against all test strains (bacteria and C. albicans) and the antagonistic activity of E. coli M-17 against the test strain C. albicans were studied by a modified method using a two-layer medium with the determination of the minimum inhibitory concentration. It was established that immobilization in alginate gel without additives and with the addition of cryoprotective components and storage for 24 months at temperatures of -20, -40, -75, -196°C did not affect the spectrum and severity of the antagonistic action of probiotics. This indicates that immobilization in a gel and storage at low temperatures do not cause damage in viable cells to genetic structures that determine chemical and biochemical reactions, which products provide the antagonistic probiotic effects.