Deletion of luxS gene mediated by ?Red gene recombination technology reduces biofilm formation and stress resistance of Lactobacillus fermentum

This study investigated the effects of the luxS gene on the biofilm formation of Lactobacillus fermentum and its stress resistance. Deletion of the luxS gene was related to the physiological characteristics of biofilm development, strain resistance, bacterial morphology, biofilm morphology, functional group types, the main components of the biofilm, and the expression of related genes. Therefore, a luxS gene-deficient strain was constructed using lambda Red gene recombination technology, and the biofilm production and stress resistance of the WT and Delta luxS strains were compared. Deletion of the gene reduced the biofilm formation of L. fermentum and its resistance to acid, bile salt, high temperatures, and a hypertonic environment. Further, this work found that its deletion affects the types of functional groups in biofilms, and at the same time downregulate the expressions of the fabI, cysE, argR, and purD genes, thus reducing the levels of fatty acids, exopolysaccharide, protein, and eDNA in biofilms. A correlation analysis found that protein in biofilms was the most important factor affecting biofilm formation. In conclusion, the luxS gene in L. fermentum is involved in the regulation of biofilm formation and stress resistance. These findings provide a theoretical basis for the study of the mechanism of biofilm formation in beneficial bacteria.