# Metabolic Influence of S. boulardii and S. cerevisiae in Cross-Kingdom Models of S. mutans and C. albicans

## TL;DR

This study explores how two yeast species, S. boulardii and S. cerevisiae, affect the metabolism of bacteria and fungi linked to tooth decay, potentially offering new probiotic strategies for dental health.

## Contribution

The novel contribution is the identification of specific metabolic regulatory effects of S. boulardii and S. cerevisiae on S. mutans and C. albicans using untargeted metabolomics.

## Key findings

- S. boulardii and S. cerevisiae down-regulated carbohydrate and amino acid metabolism in S. mutans and C. albicans.
- Both yeast species up-regulated purine metabolism, suggesting a compensatory mechanism for nucleotide synthesis.
- Dual regulatory effects were observed, indicating complex metabolic crosstalk between species.

## Abstract

Recent studies highlight the potential of Saccharomyces species as probiotics due to their ability to modulate microbial interactions and reduce cariogenic activity, yet the underlying metabolic mechanisms remain unclear. This study investigates the cross-kingdom metabolic effects of Saccharomyces boulardii and Saccharomyces cerevisiae on the metabolic processes of Streptococcus mutans and Candida albicans using a metabolomics-based approach. Untargeted LC-MS/MS analysis was conducted to assess metabolites in a planktonic model, followed by metabolomic profiling and pathway analysis to identify key metabolic alterations. The results revealed that S. boulardii and S. cerevisiae demonstrated metabolic regulatory effects on S. mutans and C. albicans. Specifically, S. boulardii down-regulated 262 metabolites and up-regulated 168, while S. cerevisiae down-regulated 265 metabolites and up-regulated 168. Both yeast species down-regulated carbohydrate and amino acid metabolism in S. mutans and C. albicans, resulting in reduced biomolecule synthesis and a less acidic environment. S. boulardii and S. cerevisiae also up-regulated certain metabolic processes, including purine metabolism, suggesting a compensatory mechanism for nucleotide synthesis. Notably, dual regulatory effects were observed, where specific metabolites were simultaneously up-regulated and down-regulated, indicating complex metabolic crosstalk. These findings suggest that both S. boulardii and S. cerevisiae modulate microbial metabolism through a shared mechanism, offering potentials for dental caries prevention.