Halitosis is a common symptom mainly caused by microbial activities in the oral cavity. Here, we used 16S rRNA gene pyrosequencing and metagenomic sequencing to examine oral microbial compositions and their functional variations in children with halitosis. We found that the tongue coating of subjects with halitosis had greater bacterial richness than those of healthy subjects. The relative abundance and prevalence of Leptotrichia wadei and Peptostreptococcus stomatis were higher in tongue coating samples from children with halitosis than those from children without halitosis; Prevotella shahii had higher relative abundance and prevalence in saliva samples from children with halitosis. We present the first comprehensive evaluation of the co-occurrence networks of saliva and tongue coating communities under healthy and halitosis conditions, and investigated patterns of significant differences between these communities. Moreover, we observed that bacterial genes associated with responses to infectious diseases and terpenoid and polyketide metabolism were enriched in subjects with halitosis, but not in healthy subjects. Hydrogen sulphide (H2S)-related metabolic pathways suggested that there was higher microbial production and less usage of H2S in subjects with halitosis. Thus, the mechanism of halitosis was implied for the first time via metagenomic sequencing.
The ban on feed antibiotics by more and more countries, and the expected ban on ZnO in feed supplementation from 2022 in the EU, urge researchers and pig producers to search for new alternatives. One possible alternative is to use the so-called “next-generation probiotics (NGPs)” derived from gastrointestinal tract.
The oral cavity is one of the most important and complicated habitats in our body and supports diverse microbial communities. In this study, we aimed to determine the bacterial diversity and composition of various oral micro-niches. Samples were collected from supragingival plaque, saliva, and tongue coating from 10 preschool children (30 samples total). 16S rRNA gene pyrosequencing dataset generated 314,639 clean reads with an average of 10,488 ± 2,787 reads per sample. The phyla Firmicutes, Proteobacteria, Actinobacteria, Bacteroidetes, and Fusobacteria were predominant, accounting for more than 90% of the total sequences. We found the highest α diversity, microbial richness, and evenness in plaque, compared with saliva and tongue coating. Plaque was also distinguished from saliva and tongue coating by phylogenetic distances (weighted UniFrac). Taxa with different relative abundances were further identified, confirming the existence of microbial differences across the three niches. Core microbiomes were defined of each niche; however, only a small proportion of operational taxonomic units (8.07%) were shared by the three niches. Coaggregation between Actinomyces spp. and Streptococcus spp. and other correlations among periodontal pathogens, such as Prevotella, Fusobacteria, Capnocytophaga, and Tannerella, were shown by a co-occurrence network. In summary, our study provides a framework of oral microbial communities in the population of preschool children as a baseline for further studies of oral diseases related to microbes.
To investigate the influence of baseline enterotypes and dietary starch type on the concentration of short-chain fatty acids (SCFA), numbers of butyrate producing bacteria and the expression of genes related to intestinal barrier and inflammatory response in the colon of finishing pigs, a 60-d in vivo trial was conducted. A 2-wk pre-trial with 102 crossbred (Duroc × [Landrace × Yorkshire]) finishing barrows (90 d old) was conducted to screen enterotypes. Then, a total of 32 pigs (87.40 ± 2.76 kg) with high (HPBR, ≥ 14) and low (LPBR, ≤ 2) Prevotella -to- Bacteroides ratios (PBR) in equal measure were selected and randomly divided into 4 groups with 8 replicates per group and 1 pig per replicate. The trial was designed following a 2 (PBR) × 2 (amylose-to-amylopectin ratio, AMR) factorial arrangement. Pigs with different PBR were fed diets based on corn-soybean meal with high AMR (HAMR, 1.24) or low AMR (LAMR, 0.23), respectively. Results showed that neither PBR nor AMR influenced the growth performance of pigs. HPBR pigs fed HAMR diet had a higher number of colonic Clostridium cluster XIVa and higher gene expression of butyrate kinase compared to the LPBR pigs ( P < 0.05). The HPBR pigs fed HAMR diets also had increased colonic concentrations of total SCFA and propionate compared to the LPBR pigs ( P < 0.05). Comparing with other pigs, HPBR pigs fed HAMR diets showed a lower ( P < 0.05) expression of histone deacetylases ( HDAC ) gene and higher ( P < 0.05) expression of G protein-coupled receptor 43 gene ( GPR 43 ) in the colonic mucosa. The interaction ( P < 0.05) of HPBR and HAMR was also found to decrease the gene expression of interleukin ( IL )-6, IL-12 , IL-1β and tumor necrosis factor-α ( TNF-α ) in colonic mucosa. These findings show that HAMR diet increased the abundance and activity of butyrate-producing bacteria and the concentration and absorption of SCFA, which may be associated with the decreased gene expression of inflammatory cytokines in the colonic mucosa of pigs with Prevotella -rich enterotype. All these alterations are likely to have a positive effect on the intestinal health of finishing pigs.
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