Objective To detect and analyze two important genes, comE and luxS, in quorum sensing signal pathway from Streptococcus oralis（S.oralis）. Methods The total genomic DNA of S.oralis NH521（a clinically isolated strain） was firstly extracted. The comE and luxS genes were then amplified by polymerase chain reaction（PCR） and further sequenced. The obtained sequences were compared with related sequences in GenBank. Results Target bands of both comE and luxS genes were detected by electrophoresis. The obtained gene sequences were similar to the corresponding sequences from another S.oralis strain（luxS, 95.0%; comE, 99.6%）; however, comparing to gene sequences of another species Streptococcus mutans, comE was more divergent（12.7%） than luxS gene（74.1%）. Conclusion This study successfully amplified and sequenced comE and luxS genes from S.oralis NH521 strain. The luxS gene accumulated more mutations than comE gene did between two S.oralis strains, but comE gene is more divergent than luxS gene between two Streptococcus species.
