Dental caries occurrence depends on the host diet that causes ecological and structural shifts in the dental biofilm. This biofilm is formed by several microorganisms that are organized as microbial cells communities enmeshed in self-produced extracellular polymeric substances, the extracellular matrix. Among these microorganisms, Streptococcus mutans is associated with dental caries development mainly because of its contribution in the extracellular matrix build-up via sucrose metabolization in exopolysaccharides e for being acidogenic and aciduric. The in vitro biofilm models do not completely mimic the natural environment and do not allow for controlling all parameters that can affect its development. Among the proposed models, the microcosmos model better mimics what happens in the oral cavity. In an ongoing Ph.D. project (FAPESP 2017/26623-5), it was developed the "three meals microcosm biofilm model". In this model, two strategies for inoculation of microorganisms from saliva were performed: a single inoculation and multiple inoculations. These biofilms were formed on enamel and subjected to a nutritional challenge of "feast and famine" simulating the ingestion of dietary carbohydrates. The longitudinal analyses of those biofilms showed a competition between microbial species and modification in the extracellular matrix. Also, both models yielded enamel demineralization. Therefore, the current project aims to analyze the gene expression of the microorganism in the cariogenic microcosmos biofilms via RNA-seq (transcriptome) to elucidate the role of S. mutans and versus the other species. The data validation will be performed via RT-qPCR. Statistical tests will be applied according to the distribution to interpret the results, adopting a significance level of 5%.
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