2021 Volume 71 Issue 2 Pages 88-93
Erythritol, a sugar alcohol, is used in a wide range of foods as an artificial sweetener, as well as in dentifrices and mouthrinses due to its potential caries-reducing properties. We previously showed that erythritol altered the metabolism of Porphyromonas gingivalis, a major periodontal pathogen, and reduced its abundance in dual-species biofilms with oral streptococci. In this study, we focused on volatile sulfur compounds (VSCs) responsible for oral malodor, and investigated the effects of erythritol on the VSC-producing capabilities of P. gingivalis and another periodontal pathogen, Treponema denticola.
Prior to the VSC production assay, the inhibitory effect of erythritol on P. gingivalis planktonic growth was tested in 3-fold diluted trypticase soy broth (dTSB) with or without 0.5, 1, 5, or 10% erythritol, respectively. In the VSC production assay, P. gingivalis and T. denticola were cultured in respective liquid media with or without 5-10% erythritol in ventilated flasks sealed with silicone plugs, and were incubated under anaerobic conditions without shaking for 18 and 48 h, respectively. Following homogenization by pumping, the headspace air above a certain distance from the surface of bacterial culture was collected in a gas-tight syringe, and gas chromatography was applied to determine the levels of VSCs (hydrogen sulfide, methyl mercaptan, dimethyl sulfide, and dimethyl disulfide). A comparison of VSC levels was performed using one-way analysis of variance with post-hoc paired comparisons conducted with Dunnett’s test.
In dTSB, erythritol had a moderate inhibitory effect on P. gingivalis planktonic growth. Meanwhile, erythritol showed significant concentration-dependent inhibitory effects on methyl mercaptan and dimethyl disulfide produced by P. gingivalis, and the inhibition rates of 5% erythritol were 29.0 and 90.1% and those of 10% erythritol were 72.0 and 98.4%, respectively. Hydrogen sulfide and dimethyl sulfide, which the bacterium produces only at relatively low concentrations, were not detected at all in the presence of 10% erythritol. On the other hand, erythritol did not significantly affect the VSC-producing capability of T. denticola. These results indicate that erythritol inhibits the planktonic growth and production of VSCs by P. gingivalis in a species-specific manner, and may help to improve periodontitis-associated oral malodor.
