Effect of Veillonella parvula on the physiological activity of Streptococcus mutans

The aim of this study was to observe the effect of V. parvula on the physiological activity of S. mutans and elucidate the role of V. parvula on dental caries.We constructed dual-species biofilms formed by V. parvula and S. mutans, and measured the pH dynamics, biofilm growth, Extracellular Polysaccharide (EPS) synthesis, and expression of S. mutans EPS synthesis-associated genes affected by V. parvula.pH dynamics were not altered when V. parvula and S. mutans were co-cultured during a 120 -h test period. However, S. mutans cell number and EPS synthesis in dual-species biofilms were found to be significantly higher than in single-species biofilms. Moreover, expression levels of genes encoding glucosyltransferases (gtfs), gtfB and gtfC specifically, were up-regulated when S. mutans was co-cultured with V. parvula.Our findings indicate that V. parvula is not, as previously thought, protective and associated with caries health. On the contrary, V. parvula might participate in caries development through interactions with S. mutans. This study suggests that V. parvula may have an impact on the pathogenesis of dental caries.