Journal of Pure and Applied MicrobiologyVol. 8 No. May 2014 Special Edition

The Effect of LuxS on the Biofilm Formation of Streptococcus mutans

Yueheng Li1-3 and Zhi Zhou1-3

1The college of Stomatology,Chongqing Medical University, Chongqing ,401147, China 2Department of endodontics,The Affiliated Hospital of Stomatology, Chongqing Medical University, Chongqing ,401147, China. 3Chongqing Key Laboratory for Oral Diseases and Biomedical Science, Chongqing ,401147, China.

Received on 12 April 2014 and accepted on 09 May 2014



To construct LuxS deletion mutant of Streptococcus mutans, and study the effect of luxS mutation on the biofilm formation of streptococcus mutans under various conditions, and find out the differences between luxS mutant strain and streptococcus mutans. Long flanking homology polymerase chain reaction(LFH-PCR) was introduced to generate a gene disruption construct consisting of Emr cassette with long flanking homology regions to the target gene. The electroporation competence of Streptococcus mutans was then transformed with this PCR product. Then positive transformants were counted on selective agar which containing erythromycin and identified by PCR. The streptococcus mutans-luxS mutant and the standard strain were grown in three different conditions(BHI, 2% glucose-BHI, 2% saccharobiose-BHI), and the ability of S.mutans and LuxS mutant biofilm formation was examined in 24 h by scanning electron microscopy (SEM). Identification by PCR and sequencing confirmed the validity of the LuxS deletion mutant of Streptococcus mutans. Compared with S.mutans ,the LuxS mutant maintained with 2% sucrose displayed an apparent defect in biofilm formation. Conclusions: The successful construction of the LuxS deletion mutant, and the ability of sucrose-dependent biofilm formation will be down-regulated in Streptococcus mutans after LuxS gene was knocked out.

Keywords : Streptococcus mutans; quorum sensing; LuxS gene.