This study describes the development of a new combined polysaccharide-matrix-based technology for the immobilization of Lactobacillus rhamnosus GG (LGG) bacteria in biofilm form. The new composition allows for delivering the bacteria to the digestive tract in a manner that improves their robustness compared with planktonic cells and released biofilm cells. Granules consisting of a polysaccharide matrix with probiotic biofilms (PMPB) with high cell density (>9 log CFU/g) were obtained by immobilization in the optimized nutrient medium. Successful probiotic loading was confirmed by fluorescence microscopy and scanning electron microscopy. The developed prebiotic polysaccharide matrix significantly enhanced LGG viability under acidic (pH 2.0) and bile salt (0.3%) stress conditions. Enzymatic extract of feces, mimicking colon fluid in terms of cellulase activity, was used to evaluate the intestinal release of probiotics. PMPB granules showed the ability to gradually release a large number of viable LGG cells in the model colon fluid. In vivo, the oral administration of PMPB granules in rats resulted in the successful release of probiotics in the colon environment. The biofilm-forming incubation method of immobilization on a complex polysaccharide matrix tested in this study has shown high efficacy and promising potential for the development of innovative biotechnologies.

In this study, the production rate of both water-insoluble EPS, bacterial cellulose, and water-soluble EPS, P, was improved through сultivation of their producers on a nutrient media containing industrial wastes, and their material properties were analyzed. The growth rate and productivity of Gluconoacetobacter xylinus C3 strain on media with industrial wastes was investigated. An optimal nutrient medium based on molasses was selected for the bacterial cellulose producer. The nutrient medium contains 2% molasses, 1% yeast extract and peptone in a 1: 1 ratio, 0.3% sodium hydrogen phosphate, 0.1% citric acid and 1% ethanol. Cultivation of Gluconoacetobacter xylinus C3 strain on this medium for 7 days at 25–30 °С ensures its high productivity – 8.21 g/L. The composition of the optimized medium with molasses provides high mechanical properties (tensile strength – 37.12 MPa and relative elongation at break – 3.28%) of bacterial cellulose and does not affect the polymer microfibrillar structure. A modified Czapek-Dox medium with 10% molasses and 1% peptone is preferable for the exopolysaccharide accumulation by A. pullulans C8 strain. The optimized media has an advantage over the traditionally used media in terms of the efficiency of exopolysaccharide accumulation and cost reduction. The pullulan yield in media was 10.08 g/l, that is 1.5 times higher than in a standard Czapek-Dox medium. The surface morphology and microstructure of the pullulan samples obtained on different media showed minor changes. Therefore, the replacement of carbon source for molasses in a Czapek-Dox media for pullulan production did not alter the polymer content and viscosity.

Структурные особенности бактериальной целлюлозы (БЦ) обеспечивают большую популярность ее использования для создания композитных материалов. Иммобилизация бактерий рода Bacillus в полимере БЦ придает матрице-носителю новые функциональные свойства, способствующие восстановлению и поддержке благоприятного баланса микрофлоры в ЖКТ. Внесение альгината натрия положительно влияло на синтез БЦ K. xylinus C-3, обеспечивая выход полимера – 12,11 г/л. Использован метод «адсорбции-инкубации» для поверхностной и пространственной иммобилизации Bacillus subtilis, обеспечивающий высокую концентрацию клеток – 10⁸ КОЕ на 1 г носителя. Биокомпозит БЦ/Bacillus подавлял рост E. coli, S. typhi, S. typhimurium, Citr. aerogenes, P. vulgaris до 85,4% после 24-часового контакта, а по истечении 72 часов полностью ингибировал рост и жизнеспособность тест-организмов в условиях in vitro. Иммобилизованные пробиотики по уровню резистентности к воздействию желудочного сока значительно превосходили суспензию свободных клеток микроорганизмов. Активность пробиотиков в условиях in vivo определяли на моделях экспериментального дисбактериоза. Пробиотические микрогранулы БЦ/B. subtilis могут быть использованы для коррекции микробиоценоза толстого кишечника.