Effects Of Lemon Essential Oil And Other Nature Extracts On The LuxS Transcription Of Streptococcus Mutans

Objective: Streptococcus mutans is the main cariogenic bacteria of dental plaque biofilm. Quorum sensing systems are communication systems between different species of bacteria, involved in regulating the formation of bacterial biofilms, glucose metabolism, acid capacity and secretion of a variety of virulence factors. S.mutans lux S gene encoding the Lux S protein is a key enzyme in the synthesis of S.mutans QS system AI-2 signaling molecules. Lemon essential oil and Hesperidin is natural product extracted from the lemon peel,the main component of LEO is limonene and its isomers. Tea polyphenol is a general term for the polyphenols in tea, a natural antibacterial product representative of the current international. This study taking the classic liquid dilution method measure LEO, LIM, HPN and TP acting on the S.mutans, change its acid resistance, biofilm formation and lux S gene expression levels. To investigate the effect of LEO, LIM, HPN and TP on S.mutans adhesion mechanism and virulence factor expression. To study the impact of natural product on plaque biofilm formation, thus provide the basis for ecological control of dental caries.Methods:1. Determination of the minimum inhibitory concentration of four drugs on S.mutans,adopts the double dilution method to four drugs for times dilution in TPY liquid medium, each group of three concentrations. Not to add drugs PH = 3.5-7 blank medium as the control group. Bacteria suspension with each group culture by 1:10(v/v) vaccination ratio after 48 h culture, measuring the OD.2. Adopts the double dilution method to four drugs for times dilution in TPY liquid medium, each group of four concentrations. Without adding drugs blank medium as control group. Bacteria suspension with each group culture mixed in the ratio of 1:1(v/v) vaccination in 96-well plates, removed after 48 h, measuring the OD.3. Grouping the same way as in Experiment 2. S.mutans with sterile saline to prepare a culture absorbance at 540 nm wavelength of the bacterial suspension of 1.0 OD.Placed in a thermostatic incubator at 37 ℃ after 18 h. Extract bacteria total RNA and reverse transcribed into c DNA. By real-time quantitative PCR method for determining four groups of different drugs after processing S.mutans lux S gene expression.Results:1. At PH = 6.5,the growth of S.mutans reaches a peak. By PH=6-3.5, with the decrease of PH,bacterial growth is decreasing. With the increase of the concentrationof LEO、LIM、HPN、TP, the amount of bacterial growth reduce.In the 1 / 2MIC concentrations, pairwise comparisons between four drugs,impact on the acid resistance of S.mutans LEO、TP> LIM > HPN.2. In the concentration range 1/16 MIC to 1/2MIC, with the increase of drug concentration, the inhibition rate of four drugs on S.mutans biofilm formation showed an upward trend,and LEO> TP> LIM> HPN.3. With the increase of the concentration of LEO、LIM、HPN、TP, lux S gene m RNA expression levels reduce.Conclusions:1. Suitable PH for the growth of S.mutans is 6.5.Within a certain concentration range,LEO, LIM, HPN and TP could reduce S.mutans acid resistance, the role of strength LEO, TP> LIM> HPN.2. LEO, LIM, HPN and TP showed inhibitory effect on the ability of biofilm formation on S.mutans. Under 1/2 MIC concentrations, the inhibition rate of biofilm formation LEO> TP> LIM> HPN.3. LEO, LIM, HPN and TP has inhibitory effect for S.mutans lux S transcriptional expression. The difference between LEO and LIM for S.mutans lux S have statistical significance, this shows that the LIM is the component of LEO to inhibit the transcriptional expression of lux S gene.But it does not play a major role. There are still other ingredients in LEO to inhibit lux S transcriptional expression.