The Influence Of Different Concentrations Of Sucrose And Xylitol On The Interspecies Interaction Between Streptococcus Sanguis And Streptococcus Mutans

Streptococcus sanguis is the constant member presenting a core group of intial biofilm formation. It plays an important role in the initial colonization harboring the dental enamel and in the ecological balance. The antagonism between Streptococcus sanguis and Streptococcus mutans has been known along with the formation and the development of the biofilm. The interspecies interactions are mediated through the production of H2O2 by the Streptococcus sanguis. Different carbohydrates can influence the metabolism of bacteria. Previous studies suggested that increased cariogenicity from sucrose and reduced cariogenicity from xylitol. No further studies were conducted to understand how the abilities of growth, acid production, hydrogen peroxide production of S.sanguis and the interspecies interactions between S.sanguis and S.mutans will become under different concentrations of sucrose and xylitol. The present study hypothesis different concentrations of sucrose and xylitol can influence hydrogen peroxide production of S.sanguis and further influence the the interspecies interactions between S.sanguis and S.mutans. Objective:1.To investigate the influence of different concentrations of sucrose and xylitol on the abilities of growth, acid production by S.sanguis and S.mutans;2. To investigate the influence of different concentrations of sucrose and xylitol on the abilities of hydrogen peroxide production by S.sanguis.3. To investigate the influence of different concentrations of hydrogen peroxide on the abilities of growth by S.mutans;4. To investigate the influence of different concentrations of sucrose and xylitol on the interspecies interaction between S.sanguis and S. mutans. Methods:1.S.sanguis ATCC10556,S.mutans UA159 are subjected to the experiment. Different concentrations of sucrose and xylitol were added to the experimentl groups, the absorbance(A) values of the samples’ supernatant were measured by the spectrophotometer to investigate the bacteria growth. The p H values were measured by digital p H meter and the Δp H were calculated to evaluate the influence on acidogenicity of the bacteria.2.The production capacity of H2O2 by S.sanguis was determined by o-Dianisidine dihydrochloride-horseradish peroxidase under the different concentrations of sucrose and xylitol.3.The absorbance values were measured to investigate the influence of different concentrations of H2O2 on the ability of growth by S.mutans.4. The interspecies interaction between S.sanguis and S.mutans were observed by plating method under different concentrations of sucrose and xylitol in both aerobic and anaerobic environment. Results:1.S.sanguis and S.mutans were growth well under both aerobic and anaerobic environment. The growth capacity by S.sanguis and S.mutans were as flowing: BHI+50mmol/L sucrose>BHI+5mmol/L sucrose>BHI>BHI+5mmol/L xylitol>BHI+50mmol/L. The supernatant p H were become lower and lower along with the increase of the incubation time. The oxygen has no obvious effect on the acidogenicity of S.sanguis and S.mutans(P>0.05). The acidogenicity of the bacteria show the same with the growth experiment, the better growth of the bacteria the lower of the p H value.2. Under aerobic environment with different carbohydrates the total production of H2O2 by S.sanguis were as following: BHI+50mmol/L sucrose>BHI+5mmol/L sucrose>BHI>BHI+5mmol/L xylitol>BHI+50mmol/L xylitol(P<0.05). After H2O2 concentration adjust to the absorbance at 600 nm, the result was BHI>BHI+5mmol/L sucrose > BHI+50mmol/L sucrose > BHI+5mmol/L xylitol >BHI+50mmol/L xylitol(P<0.05).3. 0.05mmol/LH2O2 can show little growth inhibition of the S.mutans. 1.5mmol/LH2O2 was fully inhibit the growth of S.mutans. The inhibition was not observed when S.sanguis and S.mutans were inoculated simultaneous.4. The capacity of the inhibition was strongest with 50mmol/L sucrose and stronger in anaerobic environment when S.mutans was inoculated first. The capacity of the inhibition was strongest with 50mmol/L sucrose and stronger in aerobic environment when S.sanguis was inoculated first. Conclusion:The different sucrose and xylitol concentrations did influence the growth and acidogenicity of S.sanguis and S.mutans and the production capacity of H2O2 by S.sanguis. Different concertrations of H2O2 did different inhibitory effect by S.mutans. The different carbohydrates and the oxygen influenced the interspecies interaction between S.sanguis and S.mutans. The capacity of the inhibition of S.mutans on S.sanguis was strongest in anaerobic environment with 50mmol/L sucrose. The capacity of the inhibition of S.sanguis on S.mutans was strongest in aerobic environment with 50mmol/L sucrose.