Screening of Lactobacillus strains that enhance SCFA uptake in intestinal epithelial cells

The objective was to screen Lactobacillus strains with strong survivability in oro-gastrointestinal tract and adhesion abilities of intestinal mucins and Caco-2 cells, and their effect on absorption of short-chain fatty acids (SCFAs) by epithelial cells was studied. The survival rate of Lactobacillus strains was studied after exposure to oral stress, gastric stress and intestinal stress successively, and then their adhesion ability was also researched. The model of intestinal epithelial cells absorbing SCFAs was established, which was used to evaluate the effect of Lactobacillus strains on Caco-2 cells absorption of SCFAs. The survival rate of Lactobacillus plantarum L58, L67, L97, L123, and L198 and Lactobacillus fermentum L146 was significantly higher than others in oro-gastrointestinal tract ( P < 0.05), which also showed high adhesion to mucins and Caco-2 cells. The model was successfully established with the Caco-2 cell line, which formed a polarized cell monolayer and developed tight junctions with an appropriate permeability coefficient for phenol red lower than 1 × 10 –6 cm/s after culturing for 15 days, and the viability of Caco-2 cells was significantly higher than other concentrations when the content of propionic acid or butyric acid was 1 mmol/L in the model. The propionic acid content in Caco-2 cells inoculated with L. plantarum L58, L67, L97, L123, and L198 was significantly higher than that of cells without L. plantarum inoculation ( P < 0.05), and the butyric acid content in cells inoculated with L. fermentum L146 was significantly higher than that of cells without inoculation ( P < 0.05). Our results highlight that L. plantarum L58, L67, L97, L123, L198 and L. fermentum L146 are more resistant to oro-gastrointestinal conditions and their high adhesion to the intestine can enhance SCFAs uptake in intestinal epithelial cells.