The Effect of Xylitol on the Growth of Three Normal Oral Commensal or Probiotic Bacteria

Xylitol is a pentitol often used as a sweetener in products such as chewing gum. It is recommended to prevent dental caries because of its inhibitory effect on the most common etiological agent of caries, Streptococcus mutans. Xylitol inhibits the growth of S. mutans by inhibiting its glycolysis, causing a futile cycle. It also inhibits the adhesion of S. mutans by reducing the expression of the gene gtfB, which causes the secretion of sticky substances. The purpose of this study was to investigate the effect of xylitol on normal oral bacteria, particularly commensal and probiotic strains. The strains tested were Streptococcus salivarius, Lactococcus lactis, and Lactobacillus casei. The strains were tested on agar and in solution at different concentrations of xylitol, .5%, 2.5%, 5%, and 10%. Transmittance of the solutions was recorded to determine differences in the amount of bacteria present. Xylitol was found to have an inhibitory effect on S. mutans as reported in addition to an inhibitory effect on L. lactis. S. salivarius and L. casei were only affected by xylitol at the highest concentrations tested, 5% and 10% xylitol