The microbiome associated with equine periodontitis and oral health

Equine periodontal disease is a common and painful condition and its severe form, periodontitis, can lead to tooth loss. Its aetiopathogenesis remains poorly understood despite recent increased awareness of this disorder amongst the veterinary profession. Bacteria have been found to be causative agents of the disease in other species, but current understanding of their role in equine periodontitis is extremely limited. The aim of this study was to use high-throughput sequencing to identify the microbiome associated with equine periodontitis and oral health. Subgingival plaque samples from 24 horses with periodontitis and gingival swabs from 24 orally healthy horses were collected. DNA was extracted from samples, the V3–V4 region of the bacterial 16S rRNA gene amplified by PCR and amplicons sequenced using Illumina MiSeq. Data processing was conducted using USEARCH and QIIME. Diversity analyses were performed with PAST v3.02. Linear discriminant analysis effect size (LEfSe) was used to determine differences between the groups. In total, 1308 OTUs were identified and classified into 356 genera or higher taxa. Microbial profiles at health differed significantly from periodontitis, both in their composition (p < 0.0001, F = 12.24; PERMANOVA) and in microbial diversity (p < 0.001; Mann–Whitney test). Samples from healthy horses were less diverse (1.78, SD 0.74; Shannon diversity index) and were dominated by the genera Gemella and Actinobacillus, while the periodontitis group samples showed higher diversity (3.16, SD 0.98) and were dominated by the genera Prevotella and Veillonella. It is concluded that the microbiomes associated with equine oral health and periodontitis are distinct, with the latter displaying greater microbial diversity

Effect of erythritol on microbial ecology of in vitro gingivitis biofilms

Gingivitis is one of the most common oral infections in humans. While sugar alcohols such as erythritol are suggested to have caries-preventive properties, it may also have beneficial effects in prevention of gingivitis by preventing maturation of oral biofilms. The aim of this study was to assess the effect of erythritol on the microbial ecology and the gingivitis phenotype of oral microcosms. Biofilms were inoculated with stimulated saliva from 20 healthy donors and grown in a gingivitis model in the continuous presence of 0 (control group), 5, and 10% erythritol. After 9 days of growth, biofilm formation, protease activity (gingivitis phenotype), and microbial profile analyses were performed. Biofilm growth was significantly reduced in the presence of erythritol, and this effect was dose dependent. Protease activity and the Shannon diversity index of the microbial profiles of the biofilms were significantly lower when erythritol was present. Microbial profile analysis revealed that presence of erythritol induced a compositional shift from periodontitis- and gingivitis-related taxa toward early colonizers. The results of this study suggest that erythritol suppresses maturation of the biofilms toward unhealthy composition. The gingivitis phenotype was suppressed and biofilm formation was reduced in the presence of erythritol. Therefore, it is concluded that erythritol may contribute to a healthy oral ecosystem in vitro

Comparison of gene expression between <i>S</i>. <i>mutans</i> C180-2 and C180-2FR.

<p><i>S</i>. <i>mutans</i> C180-2 and C180-2FR at early exponential phase (A), late exponential phase (B) and stationary phase (C). Overall expression of each selected gene in C180-2FR relative to that in C180-2 is presented as average fold-change ± SD. This experiment was repeated 3 times. All tested genes are categorized into three groups based on the type of relative fold changes. The significance level (α) was set at 0.005 (after Bonferroni correction). ** indicates <i>p</i> < 0.005. *** indicates <i>p</i> < 0.0005.</p

Colonies of <i>S</i>. <i>mutans</i> C180-2 and C180-2FR.

<p><i>S</i>. <i>mutans</i> C180-2 and C180-2FR were grown anaerobically on BHI agar or TYCSB agar for 3 days. The images of the colonies on the agar plates were taken with an Anxion stereo-microscope with 50x magnification.</p

Gene organization at two intergenic regions in <i>S</i>. <i>mutans</i> C180-2 and C180-2FR.

<p>A. Orientation of the genes up- and down-stream of the intergenic region 1 (Inter-1). The sequences of Inter-1 in C180-2, C180-2FR, <i>S</i>. <i>mutans</i> UA159, <i>S</i>. <i>mutans</i> LJ23, <i>S</i>. <i>mutans</i> NN2025 and <i>S</i>. <i>mutans</i> GS5 are given in the blue bar. The red letter indicates the SNP; the purple box indicates the TATAAT box; the red box indicates the transcription start site of the operon; B. Orientation of the genes up- and down-stream of the intergenic region 2 (Inter-2). In both A and B, the red lines indicate the location of the SNPs.</p

Identified SNPs in the genome of <i>S</i>. <i>mutans</i> C180-2 and C180-2FR.

<p>a nonsyn: non-synonymous coding SNP.</p><p>b This intergenic region is located upstream of a putative mutase and a putative permease chloride channel (<i>permease_A</i>).</p><p>c This intergenic region is located between the <i>pepX</i> and <i>glpF</i> genes.</p><p>Identified SNPs in the genome of <i>S</i>. <i>mutans</i> C180-2 and C180-2FR.</p