Effect of Magnetic Field and Environmental Ph on the Adsorption Efficiency of Cells of the Genus Lactobacillus

Abstract

Subject. Adsorption of probiotic cultures Lactobacillus acidophilus, namely strains 27 and Narine, and Lactobacillus plantarum, on high-dispersed silica. Purpose. The purpose of this study was to investigate the influence of a magnetic field with intensities of 0.03 and 0.09 T and the pH of the medium on the efficiency of cell adsorption of Lactobacillus probiotic strains. Method. Microbiological and biotechnological methods were applied in this research. Hydrogels based on high-dispersed silica "Enterosgel" and "Toxin.NET" were used as adsorbents. Neodymium magnets with intensities of 0.03 T and 0.09 T were employed to create the magnetic field. The efficiency of adsorption was evaluated by the cell survival of probiotic cultures after adsorption on hydrogel preparations under the influence of the magnetic field and in the case of pH adjustment by adding acid or alkali. The functional properties of the obtained composite preparations were assessed by the time of clot formation after milk fermentation and its acidity. Results. The research results demonstrated that immobilized cells of Lactobacillus acidophilus on the hydrogel of methylsilicic acid had enhanced protection not only against harsh conditions of the gastrointestinal tract (low pH and bile influence) but also against magnetic fields with intensities of 0.03 T and 0.09 T, which had an overall negative impact on native (non-immobilized) cells. The functional activity of cells immobilized in this way on the hydrogel based on high-dispersed silica "Enterosgel," evaluated by acidity and clot formation time, was only slightly reduced: up to 4,3-11,3%. This confirms the assumption that the assessment of cell survival by the Koch's cup method does not fully correspond to the real state of the cells. It was also determined that conducting adsorption in the pH range below 4 is impractical, and the optimal conditions for L. plantarum adsorption were in the pH range of 6 to 7. Scope of results. The research findings can be utilized for the development of complex probiotic preparations based on high-dispersed silica, which may be appropriate for preserving the functionality of probiotic cells used for starter cultures or in the production of dietary supplements containing beneficial microorganisms.