Preliminary Research About The Affect Of The HtrA And ClpP Genes On The Growth Of The Streptococcus Mutans

Objective:In order to compare the difference of the growth characteristic between the Streptococcus mutans standard strain and the mutant strains when they were cultivated in different carbon source conditions, the growth models of the standard strain, the htrA gene mutant strain, the clpP gene mutant strain and the htrA-clpP gene mutant strain were built. The function of the htrA gene and the clpP gene for the growth capacity of the Streptococcus mutans were analysed by monitoring the carbon source consumption of the four kinds of strains which grow in the culture medium with different carbon source through detection reagent.Methods:We cultivate the standard strain, the htrA gene mutant strain, the clpP gene mutant strain and the htrA-clpP gene mutant strain separately in the TPY culture that contained1%of sucrose or1%of glucose, they were cultivated under37℃and anaerobic condition, we determined the growth curve of each strain according to a certain space of time through Thermo Labsystems, in the meantime, we assayed the consumption of sucrose and glucose for each strain using the anthrone-vitriol test and glucose oxidase method. Then we analyse the differences of the growth curve and the carbon source consumption of the four strains.Results:When cultivated in the common TPY culture with1%of glucose, the exponential phase of the mutant strains is shorter than the standard strain, and the crest value of the mutant strains is obviously lower than the standard strain(P<0.05). During the whole growth period, there is no obvious difference between the absorbance values of the three mutant strains. When it is the exponential phase, the carbon source consumption of the three mutant strains is distinctly higher than the standard strain, when it reaches the stationary phase, the four kinds of the strains’ carbon source consumption become close gradually, but the carbon source consumption between the three mutant strains and the standard strain have statistical significance at every point of time(P<0.05). When cultivated in the common TPY culture with1%of sucrose, the crest value of absorbance for every strain is higher than the same strain that grow in the TPY culture medium contains glucose, the carbon source consumption of the standard strain is slightly lower than the mutant strains(P<0.05), there is no obvious difference between the three mutant strains(P<0.05). When there is no carbon source in the culture medium, the absorbance of the standard strain and the mutant strain is obviously lower than the strains that cultivated in the common TPY culture with glucose, and the crest value of absorbance of the mutant strain is lower than the standard strain.Conclusions:It has certain influence of the htrA gnen and the clpP gene on the growth capacity, the ability to consume carbon source and the starvation tolerance of the Streptococcus mutans. The growth capacity of all the strains that cultivated in the TPY culture with sucrose is more enhanced than than in the glucose.