Fructooligosaccharides Modulate Quorum-Sensing–Mediated Biofilm Formation in Lactiplantibacillus plantarum C8 via Amino Acid and Carbohydrate Metabolic Pathways

Abstract Oligosaccharides can support gut health by promoting the growth of beneficial bacteria like Lactobacillus, to help maintain gut balance and boost the immune system of the host. During the intestinal colonization, the forming biofilms can improve its adhesion and protect it from immune attacks and environmental stress. However, how oligosaccharides affect Lactobacillus biofilm formation and its probiotic effects remain unclear. This study examined how oligosaccharides influence L. plantarum C8 biofilm formation, growth, and function, using metabolomics to uncover underlying regulatory mechanisms. FOS markedly enhanced L. plantarum C8 self-aggregation (79.12%), surface hydrophobicity (32.82%), and adhesion (43.26%). Both FOS and MOS significantly upregulated biofilm-related genes, promoting biofilm maturity and stability. Quorum sensing analysis further revealed that FOS addition increased AI-2 production compared with planktonic and other biofilm samples. Furthermore, Non-targeted metabolomics has revealed that carbohydrate-related pathways, together with quorum sensing, constitute an integrated regulatory network governing biological membrane formation. Valine, leucine, and isoleucine biosynthesis pathway, was linked to enhanced extracellular polysaccharide (EPS) production. In conclusion, oligosaccharides, especially fructooligosaccharides, play a significant role in regulating the formation of biofilms mediated by quorum induction through multiple metabolic pathways.