Binding to glucans by glucan binding proteins (GbpA, -B, -C and -D) and by the Gtfs SHP099 cost facilitates bacterial adherence to tooth surfaces, inter-bacterial adhesion and accumulation

of biofilms [9, 10]. GtfBC&D and GbpABC&D, together with the adhesive extracellular glucans, constitute the sucrose-dependent pathway for S. mutans to establish on the tooth surface and are of central importance in plaque formation and development of caries [7, 9–14]. Multiple regulatory networks that integrate external signals, including the cell density-dependent Com system and other two-component regulatory systems, including CiaHR, LiaSR and VicRK, with CiaH, LiaS and VicK being the sensor kinases and CiaR, LiaR and VicR the response regulators of two-component

system, are required for biofilm formation [15–21]. S. mutans also possesses a LuxS-mediated signaling pathway that affects biofilm formation and bacteriocin production [18, 22, 23]. LuxS is PD0325901 price the enzyme that catalyzes the reactions leading to the production of the AI-2 signal molecule [24]. In addition, a number of other gene products, such as BrpA (a cell surface-associated biofilm regulatory protein), have also been shown to play critical roles in environmental stress responses and biofilm development by S. mutans [25, 26]. While much effort has been devoted to understanding the molecular mechanisms of adherence, biofilm development and virulence gene expression by S. mutans in pure cultures, there are large gaps in our knowledge of how this cariogenic bacterium behaves in response to inter-generic interactions with bacteria commonly found

in the supragingival plaque. In this study, we developed a dual-species in vitro model to examine the impact of co-cultivation of S. mutans with S. oralis Phosphatidylinositol diacylglycerol-lyase or S. sanguinis, two primary colonizers and members of the normal flora, or with Lactobacillus casei, a bacterium frequently isolated from TPX-0005 chemical structure carious sites, on biofilm formation by these bacteria and expression of known virulence factors of S. mutans. Data presented here suggest that growth in dual-species impacts surface biomass accumulation by some of the bacterial species analyzed, as compared to the respective mono-species biofilms and that the expression of known virulence factors by S. mutans can be differentially modulated by growth with other bacteria commonly found in dental plaque. Such interactions may influence the formation, architecture and pathogenic potential of human dental plaque. Methods Bacterial strains and growth conditions S. mutans UA159, S. oralis SK92 and S. sanguinis SK150 were maintained in Brain Heart Infusion (BHI, Becton, Dickinson and Company, MD), and L. casei 4646 was maintained in Lactobacillus MRS (Difco Laboratories, MI).