The regulation of simulated artificial oro-gastrointestinal transit stress on the adhesion of Lactobacillus plantarum S7

Abstract

Background: Oro-gastrointestinal stress in the digestive tract is the main stress to which orally administered probiotics are exposed. The regulation of oro-gastrointestinal transit (OGT) stress on the adhesion and survival of probiotics under continuous exposure to simulated salivary-gastric juice-intestinal juice was researched in this study.

Results: Lactobacillus plantarum S7 had a higher survival rate after exposure to simulated OGT1 (containing 0.15% bile salt) stress and OGT2 (containing 0.30% bile salt) stress. The adhesion ability of L. plantarum S7 was significantly increased by OGT1 stress (P < 0.05) but was not changed significantly by OGT2 stress (P > 0.05), and this trend was also observed in terms of the thickness of the surface material of L. plantarum S7 cells. The expression of surface proteins of L. plantarum S7, such as the 30 S ribosomal proteins, mucus-binding protein and S-layer protein, was significantly downregulated by OGT stress (P < 0.05); meanwhile, the expression of moonlight proteins, such as glyceraldehyde-3-phosphate dehydrogenase (GAPDH), phosphoglycorate kinase (PGK), beta-phosphoglucomutase (PGM1), GroEL and glucose-6-phosphate isomerase (PGI), was significantly upregulated (P < 0.05). However, the upregulation of GAPDH, PGK, PGM1 and PGI mediated by OGT1 stress was greater than those mediated by OGT2 stress. The quorum sensing pathway of L. plantarum S7 was changed significantly by OGT stress compared with no OGT stress cells (P < 0.05), and the expression of Luxs in the pathway was significantly upregulated by OGT1 stress (P < 0.05). The ABC transportation pathway was significantly altered by OGT1 stress (P < 0.05), of which the expression of the peptide ABC transporter substrate-binding protein and energy-coupling factor transporter ATP-binding protein EcfA was significantly upregulated by OGT stress (P < 0.05). The glycolide metabolism pathway was significantly altered by OGT1 stress compared with that in response to OGT2 stress (P < 0.05).

Conclusion: L. plantarum S7 had a strong ability to resist OGT stress, which was regulated by the proteins and pathways related to OGT stress. The adhesion ability of L. plantarum S7 was enhanced after continuous exposure to OGT1 stress, making it a potential probiotic with a promising future for application.

Keywords: Adhesion ability; Lactobacillus plantarum S7; Regulation; Simulated oro-gastrointestinal transit stress.

Fig. 1

Adhesion ability of LAB. A is the adhesion rate of LAB to mucins and Caco-2 cells. B is the correlation between adhesion to Caco-2 cells and mucins. Different letters indicate significant differences in adhesion rates to Caco-2 cells and mucins (P < 0.05)

Fig. 2

The effect of OGT stress on the adhesion rate of LAB. Different letters indicate significant differences in the adhesion rates of the strains (P < 0.05)

Fig. 3

The effect of OGT stress on the key adhesins of L. plantarum S7. Different letters indicate significant differences in the adhesion rates of L. plantarum S7 after exposure to simulated OGT stress (P < 0.05)

Fig. 4

The effect of OGT stress on the cell surface thickness of L. plantarum S7. A, With non-OGT stress; B, With OGT1 stress; C, With OGT2 stress

Fig. 5

Volcano plot of L. plantarum S7 DEPs in response to simulated OGT stress. A, T/C group; B, S/C group; C, T/S group

Fig. 6

GO enrichment analysis of L. plantarum S7 DEPs in response to simulated OGT stress (top 20). A, T/C group; B, S/C group; C, T/S group

Fig. 7

KEGG pathway enrichment scatter plot of DEPs of L. plantarum S7 in response to simulated OGT (top 20). A, T/C group; B, S/C group; C, T/S group