Adhesion Characteristics and Dual Transcriptomic and Proteomic Analysis of Lactobacillus reuteriSH23 upon Gastrointestinal Fluid Stress

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. reuteriSH23 were significantly decreased and biofilm production was also significantly decreased when L. reuteriSH23 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. reuteriin 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. reuteriin the GIT. Additionally, the recombinant Mub protein could also enhance the survival ability of L. reuteriSH23 in GIT stress environment. This study provides a comprehensive understanding of the adaptation and adhesion mechanisms of L. reuteriSH23 under the gastrointestinal tract by the transcriptomics and proteomics analysis, and mucus-binding proteins were involved in the adhesion and GIT tolerance process.