LAUSR

Dental plaques are mixed‐species biofilms that are related to the development of dental caries. Streptococcus mutans (S. mutans) is an important cariogenic bacterium that forms mixed‐species biofilms with Streptococcus gordonii (S. gordonii), an early colonizer of the tooth surface. The LuxS/autoinducer‐2(AI‐2) quorum sensing system is involved in the regulation of mixed‐species biofilms, and AI‐2 is proposed as a universal signal for the interaction between bacterial species. In this work, a S. gordonii luxS deficient strain was constructed to investigate the effect of the S. gordonii luxS gene on dual‐species biofilm formed by S. mutans and S. gordonii. In addition, AI‐2 was synthesized in vitro by incubating recombinant LuxS and Pfs enzymes of S. gordonii together. The effect of AI‐2 on S. mutans single‐species biofilm formation and cariogenic virulence gene expression were also assessed. The results showed that luxS disruption in S. gordonii altered dual‐species biofilm formation, architecture, and composition, as well as the susceptibility to chlorhexidine. And the in vitro synthesized AI‐2 had a concentration‐dependent effect on S. mutans biofilm formation and virulence gene expression. These findings indicate that LuxS/AI‐2 quorum‐sensing system of S. gordonii plays a role in regulating the dual‐species biofilm formation with S. mutans.