*2.1. Bacterial Strains and Culture Conditions*

The bacteria used in this study were Streptococcus mutans UA159, Fusobacterium nucleatum ATCC 25586, Veillonella parvula DSM 2008, Prevotella denticola 33-5, and Leptotrichia wadei 33-10. Streptococcus mutans, Fusobacterium nucleatum, and Veillonella parvula were commercially obtained from the American Type Culture Collection (ATCC) and the Deutsche Sammlung von Mikroorganismen und Zellkulturen (DSMZ). Prevotella denticola and Leptotrichia wadei were from the National Clinical Research Center for Oral Diseases. S. mutans and L. wadei were routinely grown at 37 ◦C in brain heart infusion broth (BHI; Difco, Sparks, MD, USA) [14,15], F. nucleatum and P. denticola were grown in BHI supplemented with 7.7 μM hemin (Sigma, St. Louis, MO, USA) and 1.2 μM Vitamin K1 (Sigma; St. Louis, MO, USA) [16], and V. parvula was grown in BHI containing 0.6% sodium lactate [17]. All bacterial strains were grown under anaerobic conditions (80% N2, 10% H2, 10% CO2) at 37 ◦C [18].
