Inhibitory Effect of<i>Enterococcus faecium</i>WB2000 on Volatile Sulfur Compound Production by<i>Porphyromonas gingivalis</i>

Abstract

Volatile sulfur compounds (VSCs) produced by oral anaerobes are the major compounds responsible for oral malodor. <i>Enterococcus faecium</i> WB2000 is recognized as an antiplaque probiotic bacterium. In this study, the effect of <i>E. faecium</i> WB2000 on VSC production by <i>Porphyromonas gingivalis</i> was evaluated, and the mechanism of inhibition of oral malodor was investigated. <i>P. gingivalis</i> ATCC 33277 was cultured in the presence of four lactic acid bacteria, including <i>E. faecium</i> WB2000. Subsequently, <i>P. gingivalis</i> ATCC 33277, W50, W83, and two clinical isolates were cultured in the presence or absence of <i>E. faecium</i> WB2000, and the emission of VSCs from spent culture medium was measured by gas chromatography. The number of <i>P. gingivalis</i> ATCC 33277 in mixed culture with <i>E. faecium</i> WB2000 decreased at 6 h, and the rate of decrease was higher than that in mixed cultures with the other lactic acid bacteria. The numbers of five <i>P. gingivalis</i> strains decreased at similar rates in mixed culture with <i>E. faecium</i> WB2000. The concentration of methyl mercaptan was lower in spent culture medium from <i>P. gingivalis</i> and <i>E. faecium</i> WB2000 cultures compared with that from <i>P. gingivalis</i> alone. Therefore, <i>E. faecium</i> WB2000 may reduce oral malodor by inhibiting the growth of <i>P. gingivalis</i> and neutralizing methyl mercaptan.