FUNCTIONAL OAT BEVERAGE FERMENTED BY L. rhamnosus SP1 WITH EMPHASIS ON ORAL HEALTH

Dental caries and periodontitis are prevalent oral diseases associated with microbial dysbiosis that can compromise oral and systemic health. Early caries control is essential to prevent pain and nutritional deficits or deficient weight growth in children, while periodontitis causes chronic low-grade inflammation, gingival bleeding, and advanced tooth loss. Specific microorganisms associated with the diseases are Streptococcus mutans and Porphyromonas gingivalis, respectively. Lacticaseibacillus rhamnosus SP1 is a strain with antagonistic potential against these pathogens. This study aimed to develop a functional oat beverage fermented with L. rhamnosus SP1, supplemented with inulin and xylitol, and evaluate its inhibitory and modulatory effects on oral ecology. Beverage development included monitoring fermentation curves, strain viability, microbiological safety, and probiotic survival during simulated digestion (INFOGEST). Concurrently, the beverage was introduced into a dynamic simulator of the oral ecosystem to assess its impact on multispecies oral biofilms. These oral biofilms, originating from saliva and oral biofilm samples of children with a family history of periodontitis (perio group) or periodontal health (health group), were cultured on hydroxyapatite-coated pins for 5 days. Following a 24-hour stabilization period in the simulator and a 48-hour period with water and basal medium, a 2-day supplementation period with the beverage was conducted (72 and 96 h). For microbial ecology assessment, DNA from samples was extracted using lysozyme and the Qiagen MiniAmp kit. The region V3-V4 of the 16S rRNA gene was amplified using specific primers 341F and 805R and sequenced on the Illumina MiSeq platform (300bp paired-end). Bioinformatics were performed via QIIME 2 using DADA2 and eHOMD. The formulation met microbiological safety standards, serving as an effective matrix for probiotic delivery with high survival post-digestion. Sequencing of the 36 biofilm samples yielded 1,395,530 high-quality reads after DADA2 filtering, mapping to 415 unique amplicon sequence variants, 57 genera, and 87 species. The perio and health groups exhibited stable Shannon entropy across 4 days, with the healt group showing reduced species richness after 72h. Beta diversity (Bray-Curtis, Weighted/Unweighted UniFrac) confirmed community clustering by experiment and time, suggesting biofilm growth stabilization by the beverage. Taxonomically, Streptococcus, Veillonella, and Granulicatella dominated baseline biofilms. Notably, Limosilactobacillus and Lacticaseibacillus expanded significantly over time in the treated health group, constituting ~30% of the community at 96h, where 8 dominant species (including Veillonella dispar, Streptococcus gordonii, Veillonella parvula, and Limosilactobacillus fermentum) represented >95% of the total abundance. Although no direct in vitro antagonistic potential inhibition against S. mutans was detected, a possible metabolic modulation occurred, marked by concomitant lactic acid depletion and increased short-chain fatty acid (SCFA) production. In conclusion, the oat-based functional beverage appears to have affected the taxonomic architecture of the oral biofilm in the samples.

Acknowledgments: This work was supported by CAPES (Finance Code 001), FAPESP (grant nº 2024/09430-2), FAEPEX/UNICAMP (grant nº 3282/25) and CNPq 318633/2025-6.