Sortase A regulates cell wall integrity, quorum sensing, and biofilm formation to modulate adhesion properties in <i>Lactiplantibacillus plantarum</i> C8

<i>Lactiplantibacillus plantarum,</i> a ubiquitous probiotic in fermented foods and the human gut, relies on gastrointestinal tract colonization for its health-promoting functions. Central to this colonization is Sortase A (SrtA), a transpeptidase that anchors LPXTG motif-containing proteins to the cell wall peptidoglycan layer. This study investigates the <i>srtA</i>-mediated regulatory axis linking cell wall integrity, biofilm formation, and quorum sensing (QS) to adhesion properties in <i>L. plantarum</i> C8 (CGMCC No. 30504). Gene Ontology (GO)-KEGG enrichment analysis reveals that <i>srtA</i> deletion disrupts pathways critical for environmental adaptation, including two-component signal transduction and AI-2-dependent QS. Furthermore, the results of differential gene expression analysis indicate that <i>srtA</i> deletion is associated with the downregulation of genes involved in pyruvate metabolism, amino sugar/nucleotide sugar metabolism (essential for exopolysaccharide biosynthesis), and cell wall-associated signaling cascades, processes linked to adhesion and colonization. The molecular-level alterations were consistent with the observed phenotypic changes, including impaired cell wall integrity, reduced adhesion, and diminished biofilm-forming capacity. These results establish a mechanistic connection between <i>srtA</i>-directed cell wall anchoring, QS-regulated biofilm dynamics, and probiotic adhesion efficacy in <i>L. plantarum</i>.IMPORTANCEGastrointestinal tract colonization is the foundation of probiotic efficacy, enabling <i>Lactiplantibacillus plantarum</i> to modulate the gut microbiota, reinforce intestinal barriers, and confer health benefits. Sortase A (SrtA) is central to this process, covalently anchoring LPXTG-containing surface proteins that mediate adhesion, biofilm formation, and immune modulation. While <i>srtA</i>'s role in pathogenic Gram-positive bacteria is well documented, its regulatory functions in non-pathogenic probiotic strains remain largely unexplored-especially regarding its integration with quorum sensing (QS) and environmental adaptation pathways. This study dissects the <i>srtA</i>-mediated molecular network in <i>L. plantarum</i> C8, revealing s<i>rtA</i> as a master regulator integrating cell wall integrity, QS-regulated biofilm dynamics, and surface protein function via pathways including pyruvate and amino sugar/nucleotide sugar metabolism. These insights provide a mechanistic foundation for engineering probiotic strains with enhanced adhesion, colonization, and persistence and offer a scientific basis for developing precision-targeted functional foods and therapeutics.