Dissecting signal molecule AI-2 mediated biofilm formation and environmental tolerance in Lactobacillus plantarum.

Quorum sensing (QS) exists in bacteria to communicate with each other and regulate group behaviors in a cell density-dependent manner, which uses signal molecule autoinducer-2 (AI-2) to intra- and inter-species communication. Effects of exogenous AI-2 on biofilm formation and environmental tolerance in Lactobacillus plantarum are the focus of this review. The responses to the exogenous AI-2 cross multiple physiological metabolic behaviors involving the bacteria growth, morphological characterization, biofilm development, extracellular polysaccharides (EPS) amount and related genes expression as well as the environmental stresses tolerance. The cell surface was smoother in the AI-2 supplemented treatments than without AI-2. Meanwhile, AI-2 had ability to promote the growth and formation of biofilm by increasing the yield of EPS, the main components of biofilm. The changes in lamC and ftsH gene expression point to altered regulation for hydrolysis process of polysaccharides as well as the potential for enhanced biofilm formation. The presence of AI-2 also significantly improved (p < 0.01) the tolerance of bile salts in L. plantarum , but the same results did not appear in acid tolerance. In conclusion, AI-2 supplementation could improve the biofilm formation and bile salts tolerance in L. plantarum , and this effect was likely modulated by facilitating EPS production and suppression polysaccharides hydrolysis. • The addition of AI-2 made the cell surface of L. plantarum smoother. • Exogenous AI-2 had positive impact on L. plantarum growth and biofilm formation. • Be promoted biofilm caused by more EPS secretion and reduced polysaccharide hydrolysis. • The ability of the strain to resist bile salts has increased under the action of AI-2. [ABSTRACT FROM AUTHOR]