Gene Expression Analysis of the <i>Streptococcus mutans</i> Competence Regulon Associated with the Biofilm Formation

Biofilm formation of Streptococcus mutans is dependent on quorum-sensing mechanism mediated by the competence stimulating peptide（CSP）. The purpose of this study was to examine whether the genes based upon previous microarray analysis were regulated by CSP and to discuss the role of the genes for the development of biofilm. RT-PCR analysis using wild-type UA159, and a comC, comD, comE and comX mutants were utilized to examine expression of these genes. Further, the transcriptional levels of these genes in comC mutant induced by CSP were analyzed. We identified newly 9 CSP - induced genes. In addition, a different temporal expression pattern was found for the competence regulatory genes during the induction of competence following synthesized CSP exposure. The identified genes associated with the RGP （rhamnose - glucose polysaccharide, cell whole antigen）synthesis pathway（SMU832 and SMU833）and cell wall biosynthesis（PknB）. Many of the genes regulated by CSP might play an important role in the various stages of biofilm formation by S. mutans.