Metabolome profiles in Porphyromonas gingivalis under erythritol stress

OBJECTIVE: We previously reported that erythritol, a kind of sugar alcohols, inhibited the development of in vitro heterotypic biofilms composed of Streptococcus gordonii and Porphyromonas gingivalis. To illustrate the underlying inhibition mechanisms of erythritol, we analyzed metabolome profiles in P. gingivalis modulated with erythritol. METHODS: P. gingivalis was anaerobically incubated with diluted trypticase soy broth with (0.8% or 10%) or without erythritol for 6 hours. Ionic metabolites were extracted from P. gingivalis cells (1 x 1010 cfu). CE-TOFMS was used to measure metabolite levels simultaneously. RESULTS: In the pentose phosphate pathway, erythritol was found to reduce ribose 5-phospate significantly, which is a precursor for nucleotide synthesis of the bacterium. Moreover, 15 out of 22 metabolites detected in the purine metabolic pathway, and 11 out of 14 metabolites in the pyrimidine metabolic pathway, respectively, were shown to be decreased by erythritol stress. Furthermore, 5 out of 6 nucleotide sugars tested and all tested amino sugars were decreased by erythritol. These metabolites are known to be necessary to synthesize cell components, including extracellular polymeric substrate (EPS) and peptide glycan, which thus could be related to suppression of biofilm formation. CONCLUSION: The present results likely uncover the underlying mechanism of erythritol effect. The sugar alcohol declines DNA&RNA synthesis resulting in retarded growth of P. gingivalis, and it also reduces metabolites essential for production of EPS and peptide glycan of the biofilm.