The Role of Secreted Polysaccharides in Augmenting Adherence and Mixed Biofilm Formation: and Studies.

The oral cavity is a complex environment harboring diverse microbial species that often co-exist within biofilms formed on oral surfaces. Within a biofilm, inter-species interactions can be synergistic in that the presence of one organism generates a niche for another enhancing colonization. Among these species are the opportunistic fungal pathogen and the bacterial species , the etiologic agents of oral candidiasis and dental caries, respectively. Recent studies have reported enhanced prevalence of in children with caries indicating potential clinical implications for this fungal-bacterial interaction. In this study, we aimed to specifically elucidate the role of -derived polysaccharide biofilm matrix components in augmenting colonization and mixed biofilm formation. Comparative evaluations of single and mixed species biofilms demonstrated significantly enhanced retention in mixed biofilms with Further, single species biofilms were enhanced upon exogenous supplementation with purified matrix material derived from biofilms. Similarly, growth in cell-free spent biofilm culture media enhanced single species biofilm formation, however, the observed increase in biofilms was significantly affected upon enzymatic digestion of polysaccharides in spent media, identifying secreted polysaccharides as a key factor in mediating mixed biofilm formation. The enhanced biofilms mediated by the various effectors was also demonstrated using confocal laser scanning microscopy. Importantly, a clinically relevant mouse model of oral co-infection was adapted to demonstrate the -mediated enhanced colonization in a host. Analyses of harvested tissue and scanning electron microscopy demonstrated significantly higher retention on teeth and tongues of co-infected mice compared to mice infected only with . Collectively, the findings from this study strongly indicate that the secretion of polysacharides from in the oral environment may impact the development of S. mutans biofilms, ultimately increasing dental caries and, therefore, oral colonization should be considered as a factor in evaluating the risk of caries.