Probiotic Effects on Multispecies Biofilm Composition, Architecture, and Caries Activity In Vitro.

Zhihui Chen,Gerd Göstemeyer,Falk Schwendicke,Sebastian Schlafer

doi:10.3390/microorganisms8091272

Zhihui Chen, Gerd Göstemeyer + Show 2 more

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https://doi.org/10.3390/microorganisms8091272

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Abstract

While probiotics have been tested for their anti-caries effect in vitro and also clinically, there is a lack of understanding of their effects on complex dental biofilms. We assessed two probiotics, Lactobacillus reuteri and Streptococcus oligofermentans, on a continuous-cultured model containing Streptococcus mutans, Lactobacillus rhamnosus and Actinomyces naeslundii. Cariogenic biofilms were grown on bovine enamel specimens and daily challenged with L. reuteri or S. oligofermentans whole culture (LC/SC) or cell-free supernatant (LS/SS) or medium only (negative control, NC) (n = 21/group) for 10 days. Biofilm was assessed via counting colony-forming units, quantitative polymerase chain reaction, and fluorescence in situ hybridization. Caries activity was determined by pH measurements and by assessing mineral loss (ΔZ) using transverse microradiography. Both LC and SC significantly reduced total and strain-specific cariogenic bacterial numbers (p < 0.05). ΔZ was reduced in LC (mean ± SD: 1846.67 ± 317.89) and SC (3315.87 ± 617.30) compared to NC (4681.48 ± 495.18, p < 0.05). No significant reductions in bacterial numbers and ΔZ was induced by supernatants. Biofilm architecture was not considerably affected by probiotic applications. Viable probiotics L. reuteri and S. oligofermentans, but not their culture supernatants, could reduce the caries activity of multi-species biofilms in vitro.

Highlights

Caries is a multifactorial disease characterized by an imbalance (“dysbiosis”) in the dental biofilm composition and activity, triggered by available fermentable carbohydrates allowing cariogenic bacterial strains to metabolize these to organic acids
A range of in vitro studies has been conducted to better understand the effects of widely available probiotic strains on dental pathogens [7,8,9], demonstrating probiotic effects mainly based on three mechanisms—an enhanced activity of the arginine deiminase system (ADS), direct inhibition of pathogens, and indirect reduction of pathogen colonization by competition for surface receptors
We aimed to employ a validated multi-species cariogenic biofilm model of S. mutans, Lactobacillus rhamnosus, and Actinomyces naeslundii to assess the effects of L. reuteri and S. oligofermentans on biofilm composition, architecture and caries activity in vitro

Summary

Introduction

Caries is a multifactorial disease characterized by an imbalance (“dysbiosis”) in the dental biofilm composition and activity, triggered by available fermentable carbohydrates allowing cariogenic (i.e., acidogenic and aciduric) bacterial strains to metabolize these to organic acids. A range of in vitro studies has been conducted to better understand the effects of widely available probiotic strains on dental pathogens [7,8,9], demonstrating probiotic effects mainly based on three mechanisms—an enhanced activity of the arginine deiminase system (ADS), direct inhibition of pathogens, and indirect reduction of pathogen colonization by competition for surface receptors. ADS activity contributes to pH homeostasis by generating alkali from L-arginine, thereby reducing the ecological advantage of aciduric pathogens while preventing dental hard tissue demineralization [10,11]. Probiotic organisms have been shown to compete for binding sites on surfaces or host cells and exclude the adherence of pathogenic bacteria [15]

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