Roles Of Mubr In The Ecological Competitions Of Oral Bacteria

This study intends to explore the roles of mubR in the ecological competition between S. mutans and S. sanguinis, so as to provide a new target for the ecological prevention and treatment of dental caries. The mub gene cluster expression and mutanobactin production of S. mutans were explored. The roles of mubR deletion on S. mutans growth, biofilm formation, and H2O2 sensitivity were observed. Dual-species biofilm of S. mutans and S. sanguinis and enamel demineralization model were constructed to investigate the roles of mubR in the ecological competition. Multiple genes in mub gene cluster of S. mutans were significantly up-regulated with treatment of 1 mM H2O2 or conditioned medium of S. sanguinis. Deletion of mubR could significantly inhibit mutanobactin synthesis. The ability to resist exogenous oxygen stress of the ΔmubR was significantly reduced. In the dual-species biofilm of S. mutans and S. sanguinis, deletion of mubR led to a significant decrease in the competitiveness of S. mutans and a significant increase in the pH of the biofilm supernatant. The acid production and demineralization ability of the mubR deleted dual-species biofilm group was remarkably weaker than that of the wild strain and the complement strain group. mubR is involved in the regulation of the oxidative stress resistance of S. mutans, interspecies competition between S. mutans and S. sanguinis and dual-species cariogenicity. These results suggest that MubR may be a new target for the ecological management of dental caries.