Evaluation of whether Streptococcus mutans extracellular matrix benefits the colonization of other species and whether localized alkali production affects that matrix

Abstract

A dental biofilm comprises several microbial species organized into communities (via interactions between microbial cells and extracellular matrix components) adhered to the tooth surface. Some species are better producers of extracellular matrix components, e.g., Streptococcus mutans. In conditions that favor the dysbiosis of this biofilm, such as consumption of sucrose in the diet, some microorganisms may have their metabolism favored to produce acids and components of the extracellular matrix that hinder the diffusion and neutralization of acids, leading to demineralization of teeth (i.e., caries disease, which affects half of the world's population). In contrast, some microbial species metabolize components present in saliva (or exogenous from the diet or topically applied) and produce alkali (substances that alkalize the microenvironment) to counteract the effect of acids. However, it remains unclear how alkali production or substrates for these metabolic reactions interfere with the synthesis of extracellular matrix components of cariogenic biofilms (i.e., insoluble glucans produced by glucosyltransferases or Gtfs). Therefore, the aim is to evaluate how non-matrix producing species (e.g., early colonizers) benefit from the matrix (scaffold) produced by S. mutans and how localized alkali production by early colonizers interferes with the matrix (e.g., Gtfs activity of S. mutans). Also, verify the effect of prebiotics (e.g., arginine, proline, aminosugars, and nitrate) on the matrix and biofilm accumulation, considering the microbial and biochemical components. Therefore, the GtfB enzyme will be used to test how prebiotics affect the activity of the main enzyme for the synthesis of insoluble glucans (whether there will be a change in the amount of glucan produced and whether the glucans are altered and, consequently, interfere with the adhesion of non-insoluble glucan producing species). Then, prebiotics will be used during the formation of multispecies biofilms to evaluate their role in the development of these biofilms. Biofilms will be evaluated to determine the microbial composition, extracellular matrix, and three-dimensional structure. Quantitative data will be analyzed via descriptive and inferential statistics (±=0.05). Changes in the evaluated parameters will show how and which prebiotics affect the development of cariogenic biofilms.