The
ability to survive in the harsh gastrointestinal tract (GIT)
environment is essential for Lactobacillus reuteri (L. reuteri) exhibiting beneficial effects. In
this study, we found that the hydrophobicity and auto-aggregation
of L. reuteri SH23 were significantly
decreased and biofilm production was also significantly decreased
when L. reuteri SH23 passes through
the simulated GIT. Furthermore, according to the comparative transcriptome
analysis, gene expression involved in the cell envelope, metabolic
processes, common stress response, regulatory systems, and transporters
were also affected. Meanwhile, label-free quantitative proteomics
was used to identify the differential expression of surface proteins
of L. reuteri in response to simulated
gastrointestinal fluid. Proteins related to the ABC transporters (Lreu_0517,
Lreu_0098, and Lreu_0296) and LPxTG anchor domain proteins were upregulated
in the cell surface after gastrointestinal fluid treatment, which
is useful for adherence and colonization of L. reuteri in the GIT. Additionally, the recombinant Mub protein could also
enhance the survival ability of L. reuteri SH23 in GIT stress environment. This study provides a comprehensive
understanding of the adaptation and adhesion mechanisms of L. reuteri SH23 under the gastrointestinal tract
by the transcriptomics and proteomics analysis, and mucus-binding
proteins were involved in the adhesion and GIT tolerance process.