Exploring the relationship between the signal molecule AI-2 and the biofilm formation of Lactobacillus sanfranciscensis

The objective of this study was to investigate the effect of the signal molecule AI-2 on biofilm formation in Lactobacillus sanfranciscensis. We found that the influence of signal molecule AI-2 on strains is related to a variety of physiological metabolic behaviors, such as bacterial growth, morphological characteristics, biofilm development, related gene expression, and bile salt stress tolerance. The survival rates of planktonic and biofilm forms of L. sanfranciscensis were measured after acid, bile salt, and in vitro digestion. The results showed that the biofilm strain had stronger stress resistance. Next, the effects of endogenous and synthetic AI-2 on L. sanfranciscensis growth were compared. The addition of synthetic AI-2 improved L. sanfranciscensis cell density and enhanced bacterial cohesion. Upregulated expression of ftsH was found to promote biofilm formation and growth. AI-2 intervention will improve bile salt tolerance in L. sanfranciscensis. In conclusion, the signal molecule AI-2 is involved in the regulation of biofilm formation and development in L. sanfranciscensis.