Veillonellae: Beyond Bridging Species in Oral Biofilm Ecology

Glycolanguage of the oral microbiota

The oral cavity harbors a diverse and dynamic bacterial biofilm community which is pivotal to oral health maintenance and, if turning dysbiotic, can contribute to various diseases. Glycans as unsurpassed carriers of biological information are participating in underlying processes that shape oral health and disease. Bacterial glycoinfrastructure-encompassing compounds as diverse as glycoproteins, lipopolysaccharides (LPSs), cell wall glycopolymers, and exopolysaccharides-is well known to influence bacterial fitness, with direct effects on bacterial physiology, immunogenicity, lifestyle, and interaction and colonization capabilities. Thus, understanding oral bacterias' glycoinfrastructure and encoded glycolanguage is key to elucidating their pathogenicity mechanisms and developing targeted strategies for therapeutic intervention. Driven by their known immunological role, most research in oral glycobiology has been directed onto LPSs, whereas, recently, glycoproteins have been gaining increased interest. This review draws a multifaceted picture of the glycolanguage, with a focus on glycoproteins, manifested in prominent oral bacteria, such as streptococci, Porphyromonas gingivalis, Tannerella forsythia, and Fusobacterium nucleatum. We first define the characteristics of the different glycoconjugate classes and then summarize the current status of knowledge of the structural diversity of glycoconjugates produced by oral bacteria, describe governing biosynthetic pathways, and list biological roles of these energetically costly compounds. Additionally, we highlight emerging research on the unraveling impact of oral glycoinfrastructure on dental caries, periodontitis, and systemic conditions. By integrating current knowledge and identifying knowledge gaps, this review underscores the importance of studying the glycolanguage oral bacteria speak to advance our understanding of oral microbiology and develop novel antimicrobials.

A study on the causal relationship between the gut microbiome and herpes zoster using Mendelian randomization

Introduction

The relationship between herpes zoster recurrence and the gut microbiome was not studied. We analyzed data on the gut microbiome and herpes zoster from the Large-Scale Genome-Wide Association Study (GWAS) database using bidirectional Mendelian randomization. For the first time, we identified a potentially bidirectional causal relationship between the gut microbiome and herpes zoster (HZ). These findings are groundbreaking and hold promise for new directions in the treatment of HZ, a global disease.

Background and aims

HZ had a high global incidence, characterized by shingled blisters, blood blisters, and neuropathic pain, and could develop in various parts of the body, including the ear and throat. It was believed its onset was closely related to old age and infirmity. Some studies reported that the incidence of herpes zoster in patients with inflammatory intestinal diseases (such as Crohn's disease and ulcerative colitis) was higher than in the general population. Existing studies attributed this to the reactivation of varicella-zoster virus (VZV) due to autoinflammatory attacks and immunosuppressive drugs. This provided a basis for exploring the new pathogenesis of HZ and investigating whether there was a relationship between intestinal auto-flora and the development of HZ. This study aimed to examine this potential relationship using bidirectional Mendelian analyses.

Methods

GWAS data on HZ and gut microbiota were obtained from FinnGen, the Mibiogen consortium, and HZ meta-analysis data from the IEU Open GWAS Project. These data were subjected to two-sample Mendelian randomization (MR) analysis to determine if there is a causal relationship between gut microbiota and HZ. Additionally, bidirectional Mendelian analyses were conducted to identify the direction of causality and to clarify any potential interactions.

Results

In our Mendelian Randomization (MR) analysis, we identified, for the first time, two gut microbes that might be associated with HZ reactivation. In the reverse MR analysis, four gut microbiota showed a potential association between the genetic susceptibility of gut microbiota and HZ reactivation. We found that genus Tyzzerella3 (OR: 1.42, 95% CI: 1.17-1.72, FDR < 0.1) may be strongly correlated with an increased probability of HZ (ICD-10: B02.901) reactivation. Additionally, phylum Cyanobacteria was identified as a potential risk factor for the onset of HZ rekindling (OR: 1.42, 95% CI: 1.09-1.87). Analyzing the results of the reverse MR, we also identified a potential inhibitory effect (OR: 0.91, 95% CI: 0.84-0.99) of HZ onset on the genus Eubacteriumhallii group in the gut, suggesting that HZ might reduce its abundance. However, genus Escherichia/Shigella (OR: 1.11, 95% CI: 1.01-1.22), genus Veillonella (OR: 1.16, 95% CI: 1.04-1.30), and phylum Proteobacteria (OR: 1.09, 95% CI: 1.01-1.18) appeared to act as potential protective factors, indicating that the relative abundance and viability of these three bacteria increased in the HZ state.

Conclusion

We identified the influence of gut flora as a new causative factor for HZ reactivation. Additionally, we found that individuals suffering from HZ might potentially impact their gut flora. Specific bacterial taxa that could influence the onset and progression of HZ were identified, potentially providing new directions for HZ treatment.

Delivery mode and maternal gestational diabetes are important factors in shaping the neonatal initial gut microbiota

Background

The infant gut microbiome's establishment is pivotal for health and immune development. Understanding it unveils insights into growth, development, and maternal microbial interactions. Research often emphasizes gut bacteria, neglecting the phageome.

Methods

To investigate the influence of geographic or maternal factors (mode of delivery, mode of breastfeeding, gestational diabetes mellitus) on the gut microbiota and phages of newborns, we collected fecal samples from 34 pairs of mothers and their infants within 24 hours of delivery from three regions (9 pairs from Enshi, 7 pairs from Hohhot, and 18 pairs from Hulunbuir) using sterile containers. Gut microbiota analysis by Shotgun sequencing was subsequently performed.

Results

Our results showed that geographic location affects maternal gut microbiology (P < 0.05), while the effect on infant gut microbiology was not significant (P = 0.184). Among the maternal factors, mode of delivery had a significant (P < 0.05) effect on the newborn. Specific bacteria (e.g., Bacteroides, Escherichia spp., Phocaeicola vulgatus, Escherichia coli, Staphylococcus hominis, Veillonella spp.), predicted active metabolites, and bacteriophage vOTUs varied with delivery mode. Phocaeicola vulgatus significantly correlated with some metabolites and bacteriophages in the early infant gut (P < 0.05). In the GD group, a strong negative correlation of phage diversity between mother and infants was observed (R = -0.58, P=0.04).

Conclusion

In conclusion, neonatal early gut microbiome (including bacteria and bacteriophages) colonization is profoundly affected by the mode of delivery, and maternal gestational diabetes mellitus. The key bacteria may interact with bacteriophages to influence the levels of specific metabolites. Our study provides new evidence for the study of the infant microbiome, fills a gap in the analysis of the infant gut microbiota regarding the virome, and emphasizes the importance of maternal health for the infant initial gut virome.

Assessing oral and toothbrush microbial profiles among high-altitude individuals with and without periodontal disease: a case-control study

BACKGROUND

Periodontitis is the sixth-most common disease worldwide. The oral microbiome composition and its association with Periodontal disease (PD) have been largely explored; however, limited studies have explored the microbial profiles of both oral and toothbrushes in patients with PD. Thus, this study aimed to ascertain the oral and toothbrushes microbial composition in high-altitude populations, hypothesizing that their correlation with periodontal health would differ from those at lower altitudes, potentially indicating links between environmental factors, microbial colonization patterns, and periodontal health in distinct geographic contexts.

METHODS

In the present study, we enrolled 35 individuals including 21 healthy and 14 diagnosed with PD from the Lhasa region of Tibet, China. Saliva and toothbrush samples were collected from each participant to assess the association between toothbrush usage and oral microbiome with PD using 16 S rRNA gene-specific V3-V4 regions sequencing. To assess the oral and toothbrush microbiome composition and diversity and its possible link to PD.

RESULTS

Significantly higher Alpha diversity (Shannon index) was observed between the PD group and PD toothbrushes (p = 0.00021) and between the PD group and Healthy toothbrushes (p = 0.00041). The predominant species were Proteobacteria, Bacteroidota, Firmicutes, Actinobacteria, and Fusobacteria, with genera Pseudomonas, Veillonella, Neisseria, Acinetobacter, and Haemophilus. In addition, PICRUST2 analysis unveiled 44 significant pathways differentiating the disease and healthy groups, along with 29 pathways showing significant differences between their respective toothbrush microbial profiles. The distinct oral and toothbrush microbial composition among high-altitude populations suggests potential adaptations to the challenges of high-altitude environments.

CONCLUSION

This study emphasizes the importance of tailored dental care strategies, accounting for altitude and racial factors, to effectively manage periodontal health in these communities. Further research is warranted to investigate the specific microbial mechanisms and develop targeted interventions for optimizing oral health in populations across varying altitudes.

Development of a small shuttle plasmid for use in oral Veillonella and initial appraisal of potential for fluorescence-based applications

Oral Veillonella species are among the early colonizers of the human oral cavity. We constructed a small, single-selectable-marker shuttle plasmid, examined its ability to be transformed into diverse oral Veillonella strains, and assessed its potential use for expressing a gene encoding an oxygen-independent fluorescent protein, thus generating a fluorescent Veillonella parvula strain. Because tetracycline resistance is common in Veillonella, we replaced genes encoding ampicillin- and tetracycline-resistance in a previously described shuttle plasmid (pBSJL2) with a chloramphenicol acetyltransferase gene. The resulting plasmid pCF1135 was successfully introduced into four strains representing V. parvula and V. atypica by either natural transformation or electroporation. We then modified this plasmid to express a gene encoding an oxygen-independent fluorescent protein in V. parvula SKV38. The resulting strain yielded a fluorescence signal intensity ∼16 times higher than the wild type in microplate-based fluorimetry experiments. While fluorescence microscopy demonstrated that planktonic cells, colonies, and biofilms of fluorescent V. parvula could also be imaged, photobleaching was a significant issue. In conclusion, we anticipate this genetic system and information provided here will facilitate expanded studies of oral Veillonella species' properties and behavior.

Nepali oral microbiomes reflect a gradient of lifestyles from traditional to industrialized

Background

Lifestyle plays an important role in shaping the gut microbiome. However, its contributions to the oral microbiome remains less clear, due to the confounding effects of geography and methodology in investigations of populations studied to date. Furthermore, while the oral microbiome seems to differ between foraging and industrialized populations, we lack insight into whether transitions to and away from agrarian lifestyles shape the oral microbiota. Given the growing interest in so-called 'vanishing microbiomes' potentially being a risk factor for increased disease prevalence in industrialized populations, it is important that we distinguish lifestyle from geography in the study of microbiomes across populations.

Results

Here, we investigate salivary microbiomes of 63 Nepali individuals representing a spectrum of lifestyles: foraging, subsistence farming (individuals that transitioned from foraging to farming within the last 50 years), agriculturalists (individuals that have transitioned to farming for at least 300 years), and industrialists (expatriates that immigrated to the United States within the last 20 years). We characterize the role of lifestyle in microbial diversity, identify microbes that differ between lifestyles, and pinpoint specific lifestyle factors that may be contributing to differences in the microbiomes across populations. Contrary to prevailing views, when geography is controlled for, oral microbiome alpha diversity does not differ significantly across lifestyles. Microbiome composition, however, follows the gradient of lifestyles from foraging through agrarianism to industrialism, supporting the notion that lifestyle indeed plays a role in the oral microbiome. Relative abundances of several individual taxa, including Streptobacillus and an unclassified Porphyromonadaceae genus, also mirror lifestyle. Finally, we identify specific lifestyle factors associated with microbiome composition across the gradient of lifestyles, including smoking and grain source.

Conclusion

Our findings demonstrate that by controlling for geography, we can isolate an important role for lifestyle in determining oral microbiome composition. In doing so, we highlight the potential contributions of several lifestyle factors, underlining the importance of carefully examining the oral microbiome across lifestyles to improve our understanding of global microbiomes.

Prevalence of dental caries among children in Indonesia: A systematic review and meta-analysis of observational studies

Objective

The prevalence of dental caries among children in Indonesia remains unclear. Therefore, we aimed to provide an updated assessment of this prevalence while also investigating the influence of patient characteristics and methodological factors.

Design

We performed a systematic review and meta-analysis, including searches of PubMed, Cochrane Library, and Embase from inception to August 24, 2023. We included 8840 participants in 27 studies reporting the prevalence of dental caries among Indonesian children.

Results

The overall prevalence of dental caries was 76 % (95 % confidence interval: 71%-81 %). Studies in which decay-missing-filled teeth (DMFT) criteria were used to diagnose dental caries were significantly more prevalent than studies using non-DMFT criteria (78 % vs. 64 %, P < 0.05). No significant moderators were identified for the study subgroup based on study origin (Jakarta vs. non-Jakarta) or comorbidity status (comorbidity vs. no comorbidity). Owing to incomplete reporting of variables, metaregression analysis could not be conducted for continuous variables, such as age and male percentage.

Conclusions

The prevalence of dental caries among Indonesian children remains notably high, showing consistency across Jakarta-based studies and non-Jakarta studies. Initiating dental caries prevention and health promotion campaigns is imperative, focusing on the critical importance of early detection.

Characteristics of the oral microbiota in patients with primary Sjögren's syndrome

OBJECTIVE

Primary Sjögren's syndrome (pSS) is an autoimmune disease with unknown etiology that is considered to be related to environmental and genetic factors. The aim of this study was to clarify the oral microflora characteristics of pSS patients and to reveal the connection between oral bacterial composition and dental caries using a high-throughput sequencing technique.

METHODS

Thirty-five pSS patients and 20 healthy controls were enrolled in this study. We collected saliva and plaque samples from pSS patients and saliva samples from healthy controls. We used 16S ribosomal DNA (16S rDNA) high-throughput sequencing targeting the V3-V4 hypervariable region to determine the composition and structure of the microbiota in the three sample sets. Finally, bioinformatics analyses, including the diversity of the microbiota, species differences, and functional prediction were performed.

RESULTS

In the alpha diversity and beta diversity analysis, the Chao1 (P < 0.01), observed species (P < 0.01), and PD whole tree indices (P < 0.01) were significantly lower in the saliva and plaque samples of pSS patients than in the saliva samples of healthy controls, but the Shannon (P < 0.01) and Simpson indices (P < 0.01) were significantly higher in the healthy controls, and their total diversity significantly differed. In the main flora composition at the genus level (top 10), we identified Prevotella and Veillonella as more enriched in the saliva of pSS patients and Fusobacterium, Actinomyces, and Leptotrichia as more enriched in the plaque of pSS patients. Predictive functional analysis showed that the oral microbiota of pSS patients was related to translation, metabolism of cofactors and vitamins, and nucleotide metabolism.

CONCLUSIONS

The oral microbial ecology of patients with pSS is dysregulated, resulting in a decrease in overall diversity. Prevotella and Veillonella may be related to pSS, while Fusobacterium, Actinomyces, and Leptotrichia may be related to dental caries in pSS patients. Key Points • This study revealed differences in the oral microbial composition of patients with pSS compared to healthy controls. • We included a plaque group of pSS patients to identify the microbiota related to pSS and dental caries. • Prevotella and Veillonella may contribute to pSS, and Fusobacterium, Actinomyces, and Leptotrichia are associated with dental caries in pSS patients.

Microbial diagnostics in periodontal diseases

Microbial analytical methods have been instrumental in elucidating the complex microbial etiology of periodontal diseases, by shaping our understanding of subgingival community dynamics. Certain pathobionts can orchestrate the establishment of dysbiotic communities that can subvert the host immune system, triggering inflammation and tissue destruction. Yet, diagnosis and management of periodontal conditions still rely on clinical and radiographic examinations, overlooking the well-established microbial etiology. This review summarizes the chronological emergence of periodontal etiological models and the co-evolution with technological advances in microbial detection. We additionally review the microbial analytical approaches currently accessible to clinicians, highlighting their value in broadening the periodontal assessment. The epidemiological importance of obtaining culture-based antimicrobial susceptibility profiles of periodontal taxa for antibiotic resistance surveillance is also underscored, together with clinically relevant analytical approaches to guide antibiotherapy choices, when necessary. Furthermore, the importance of 16S-based community and shotgun metagenomic profiling is discussed in outlining dysbiotic microbial signatures. Because dysbiosis precedes periodontal damage, biomarker identification offers early diagnostic possibilities to forestall disease relapses during maintenance. Altogether, this review highlights the underutilized potential of clinical microbiology in periodontology, spotlighting the clinical areas most conductive to its diagnostic implementation for enhancing prevention, treatment predictability, and addressing global antibiotic resistance.

Mutualistic interactions of lactate-producing lactobacilli and lactate-utilizing Veillonella dispar: Lactate and glutamate cross-feeding for the enhanced growth and short-chain fatty acid production

The human gut hosts numerous ecological niches for microbe-microbe and host-microbe interactions. Gut lactate homeostasis in humans is crucial and relies on various bacteria. Veillonella spp., gut lactate-utilizing bacteria, and lactate-producing bacteria were frequently co-isolated. A recent clinical trial has revealed that lactate-producing bacteria in humans cross-feed lactate to Veillonella spp.; however, their interspecies interaction mechanisms remain unclear. Veillonella dispar, an obligate anaerobe commonly found in the human gut and oral cavity, ferments lactate into acetate and propionate. In our study, we investigated the interaction between V. dispar ATCC 17748T and three representative phylogenetically distant strains of lactic acid bacteria, Lactobacillus acidophilus ATCC 4356T, Lacticaseibacillus paracasei subsp. paracasei ATCC 27216T, and Lactiplantibacillus plantarum ATCC 10241. Bacterial growth, viability, metabolism and gene level adaptations during bacterial interaction were examined. V. dispar exhibited the highest degree of mutualism with L. acidophilus. During co-culture of V. dispar with L. acidophilus, both bacteria exhibited enhanced growth and increased viability. V. dispar demonstrated an upregulation of amino acid biosynthesis pathways and the aspartate catabolic pathway. L. acidophilus also showed a considerable number of upregulated genes related to growth and lactate fermentation. Our results support that V. dispar is able to enhance the fermentative capability of L. acidophilus by presumably consuming the produced lactate, and that L. acidophilus cross-feed not only lactate, but also glutamate, to V. dispar during co-culture. The cross-fed glutamate enters the central carbon metabolism in V. dispar. These findings highlight an intricate metabolic relationship characterized by cross-feeding of lactate and glutamate in parallel with considerable gene regulation within both L. acidophilus (lactate-producing) and V. dispar (lactate-utilizing). The mechanisms of mutualistic interactions between a traditional probiotic bacterium and a potential next-generation probiotic bacterium were elucidated in the production of short-chain fatty acids.

Oral Biofilm Composition, Dissemination to Keratinocytes, and Inflammatory Attenuation Depend on Probiotic and Synbiotic Strain Specificity

Several inflammatory diseases are characterized by a disruption in the equilibrium between the host and its microbiome. Due to the increase in resistance, the use of antibiotics for the widespread, nonspecific killing of microorganisms is at risk. Pro-microbial approaches focused on stimulating or introducing beneficial species antagonistic toward pathobionts may be a viable alternative for restoring the host-microbiome equilibrium. Unfortunately, not all potential probiotic or synbiotic species and even subspecies (to strain level) are equally effective for the designated pathology, leading to conflicting accounts of their efficacy. To assess the extent of these species- and strain-specific effects, 13 probiotic candidates were evaluated for their probiotic and synbiotic potential with glycerol on in vitro oral biofilms, dissemination from biofilms to keratinocytes, and anti-inflammatory activity. Species- and strain-specific effects and efficacies were observed in how they functioned as probiotics or synbiotics by influencing oral pathobionts and commensals within biofilms and affected the dissemination of pathobionts to keratinocytes, ranging from ineffective strains to strains that reduced pathobionts by 3 + log. In addition, a minority of the candidates exhibited the ability to mitigate the inflammatory response of LPS-stimulated monocytes. For a comprehensive assessment of probiotic therapy for oral health, a judicious selection of fully characterized probiotic strains that are specifically tailored to the designated pathology is required. This approach aims to challenge the prevailing perception of probiotics, shifting the focus away from "form over function." Rather than using unproven, hypothetical probiotic strains from known genera or species, one should choose strains that are actually functional in resolving the desired pathology before labelling them probiotics.

Effects of glucose and lactate on Streptococcus mutans abundance in a novel multispecies oral biofilm model

The oral microbiome plays an important role in protecting oral health. Here, we established a controlled mixed-species in vitro biofilm model and used it to assess the impact of glucose and lactate on the ability of Streptococcus mutans, an acidogenic and aciduric species, to compete with commensal oral bacteria. A chemically defined medium was developed that supported the growth of S. mutans and four common early colonizers of dental plaque: Streptococcus gordonii, Actinomyces oris, Neisseria subflava, and Veillonella parvula. Biofilms containing the early colonizers were developed in a continuous flow bioreactor, exposed to S. mutans, and incubated for up to 7 days. The abundance of bacteria was estimated by quantitative polymerase chain reaction (qPCR). At high glucose and high lactate, the pH in bulk fluid rapidly decreased to approximately 5.2, and S. mutans outgrew other species in biofilms. In low glucose and high lactate, the pH remained above 5.5, and V. parvula was the most abundant species in biofilms. By contrast, in low glucose and low lactate, the pH remained above 6.0 throughout the experiment, and the microbial community in biofilms was relatively balanced. Fluorescence in situ hybridization confirmed that all species were present in the biofilm and the majority of cells were viable using live/dead staining. These data demonstrate that carbon source concentration is critical for microbial homeostasis in model oral biofilms. Furthermore, we established an experimental system that can support the development of computational models to predict transitions to microbial dysbiosis based on metabolic interactions.IMPORTANCEWe developed a controlled (by removing host factor) dynamic system metabolically representative of early colonization of Streptococcus mutans not measurable in vivo. Hypotheses on factors influencing S. mutans colonization, such as community composition and inoculation sequence and the effect of metabolite concentrations, can be tested and used to predict the effect of interventions such as dietary modifications or the use of toothpaste or mouthwash on S. mutans colonization. The defined in vitro model (species and medium) can be simulated in an in silico model to explore more of the parameter space.

Analysis of subgingival microbiota and IL-1β, TNF-α and CX3CL1 levels in gingival crevicular fluid of fixed dental prostheses

Prosthetic biomaterials can affect the composition of the subgingival microbiota and consequently the production of proinflammatory cytokines, causing damage to the periodontium. A total of 40 patients were divided into two groups: 20 with monolithic zirconia (MZ) prostheses and 20 with porcelain fused to metal (PFM) with nickel-chromium (Ni-Cr) alloy prostheses. Subgingival plaque and gingival crevicular fluid samples were taken. The Checkerboard technique for DNA-DNA hybridization and the enzyme-linked immunosorbent assay technique were performed. Teeth with MZ presented a lower percentage of bleeding on probing and tooth mobility compared to teeth with PFM with Ni-Cr alloy. Prosthodontic teeth harbored higher total levels of the 18 bacterial species than non-prosthodontic teeth. There was a higher prevalence of S. gordonii and V. parvula species in PFM with Ni-Cr alloy compared to MZ. There was an increase in IL-1β, TNF-α and CX3CL1 levels in PFM with Ni-Cr alloy compared to MZ. MZ is a candidate biomaterial with fewer negative effects on the periodontium, allowing for longer prostheses longevity in the mouth.

Functional contribution of the intestinal microbiome in autism spectrum disorder, attention deficit hyperactivity disorder, and Rett syndrome: a systematic review of pediatric and adult studies

Introduction

Critical phases of neurodevelopment and gut microbiota diversification occur in early life and both processes are impacted by genetic and environmental factors. Recent studies have shown the presence of gut microbiota alterations in neurodevelopmental disorders. Here we performed a systematic review of alterations of the intestinal microbiota composition and function in pediatric and adult patients affected by autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), and Rett syndrome (RETT).

Methods

We searched selected keywords in the online databases of PubMed, Cochrane, and OVID (January 1980 to December 2021) with secondary review of references of eligible articles. Two reviewers independently performed critical appraisals on the included articles using the Critical Appraisal Skills Program for each study design.

Results

Our systematic review identified 18, 7, and 3 original articles describing intestinal microbiota profiles in ASD, ADHD, and RETT, respectively. Decreased Firmicutes and increased Bacteroidetes were observed in the gut microbiota of individuals affected by ASD and ADHD. Proinflammatory cytokines, short-chain fatty acids and neurotransmitter levels were altered in ASD and RETT. Constipation and visceral pain were related to changes in the gut microbiota in patients affected by ASD and RETT. Hyperactivity and impulsivity were negatively correlated with Faecalibacterium (phylum Firmicutes) and positively correlated with Bacteroides sp. (phylum Bacteroidetes) in ADHD subjects. Five studies explored microbiota-or diet-targeted interventions in ASD and ADHD. Probiotic treatments with Lactobacillus sp. and fecal microbiota transplantation from healthy donors reduced constipation and ameliorated ASD symptoms in affected children. Perinatal administration of Lactobacillus sp. prevented the onset of Asperger and ADHD symptoms in adolescence. Micronutrient supplementation improved disease symptomatology in ADHD without causing significant changes in microbiota communities' composition.

Discussion

Several discrepancies were found among the included studies, primarily due to sample size, variations in dietary practices, and a high prevalence of functional gastrointestinal symptoms. Further studies employing longitudinal study designs, larger sample sizes and multi-omics technologies are warranted to identify the functional contribution of the intestinal microbiota in developmental trajectories of the human brain and neurobehavior.

Systematic review registration

https://clinicaltrials.gov/, CRD42020158734.

Interdental oral hygiene interventions elicit varying compositional microbiome changes in naturally occurring gingivitis: Secondary data analysis from a clinical trial

AIM

To evaluate the effect of different oral irrigators on the sub-gingival microbiome composition in patients with naturally occurring plaque-induced gingivitis.

MATERIALS AND METHODS

Sub-gingival plaque was collected from adults participating in a clinical trial assessing the efficacy of oral hygiene with two different oral irrigators (Waterpik Water Flosser [Group 1] and Oral-B Water Flosser [Group 2]) versus dental flossing (Group 3) for microbiome analysis. Plaque samples were reflective of naturally occurring plaque-induced gingivitis at baseline and of gingival health at the endpoint (4 weeks). Clinical measures of gingival inflammation were collected, and the sub-gingival microbiome was analysed by 16S rRNA sequencing to identify amplicon sequence variants.

RESULTS

Oral hygiene instruction with self-performed manual toothbrushing and water-jet irrigation led to significant reductions in inflammation for all groups; both oral irrigators outperformed flossing in bleeding-on-probing reduction (p < .001). Microbiome diversity of sub-gingival plaque remained relatively stable over time, but significant changes were noted in certain taxa, consistent with increases in the relative abundance of commensals and reductions in late colonizers and periodontal pathogens in the water-jet groups.

CONCLUSIONS

Reduction in gingival inflammation at 4 weeks within the water-jet groups is accompanied by slight but critical changes in microbiome composition. Although biodiversity does not substantially change within 4 weeks during the resolution of naturally induced gingivitis, significant relative increases in commensal early colonizers such as Streptococcus, Veillonella and Fusobacterium were accompanied by a shift towards a less anaerobic microbiota associated with return to health. These changes were contingent upon the type of interdental hygiene, with Group 1 exhibiting more significant alterations in microbiome composition towards a periodontal-health-compatible community.

Interplay between dental caries pathogens, periodontal pathogens, and sugar molecules: approaches for prevention and treatment

Globally, oral diseases affect nearly 3.5 billion people, accounting for 4.6% of the healthcare expenditure. Common oral diseases include dental caries and periodontal disease, associated with biofilms formed by cariogenic pathogens. Epidemiological studies associate carbohydrates with these diseases due to  the sugars metabolized by cariogenic pathogens. This review focuses on dental caries and periodontal pathogens, quorum sensing, lectin-carbohydrate interactions, and various sugar molecules. Cariogenic sugars significantly influence biofilms by enhancing pathogen adhesion, viability, and gene expressions associated with biofilm formation. Moreover, lectin-carbohydrate interactions contribute to biofilm stability. Disrupting these interactions is a potential strategy for oral disease prevention. The use of nanoparticles, such as quantum dots, provides novel insights into lectin-sugar interactions and the development of inhibitors. Additionally, nanomaterials like calcium phosphate nanoparticles neutralize acids and inhibit microbial growth. This overview emphasizes understanding the relationships between oral diseases, microbial communities, and sugars to devise preventive and therapeutic strategies against oral diseases.

The effects of nitrate on the oral microbiome: a systematic review investigating prebiotic potential

Background

Nitrate (NO3-) has been suggested as a prebiotic for oral health. Evidence indicates dietary nitrate and nitrate supplements can increase the proportion of bacterial genera associated with positive oral health whilst reducing bacteria implicated in oral disease(s). In contrast, chlorhexidine-containing mouthwashes, which are commonly used to treat oral infections, promote dysbiosis of the natural microflora and may induce antimicrobial resistance.

Methods

A systematic review of the literature was undertaken, surrounding the effects of nitrate on the oral microbiota.

Results

Overall, n = 12 in vivo and in vitro studies found acute and chronic nitrate exposure increased (representatives of) health-associated Neisseria and Rothia (67% and 58% of studies, respectively) whilst reducing periodontal disease-associated Prevotella (33%). Additionally, caries-associated Veillonella and Streptococcus decreased (25% for both genera). Nitrate also altered oral microbiome metabolism, causing an increase in pH levels (n = 5), which is beneficial to limit caries development. Secondary findings highlighted the benefits of nitrate for systemic health (n = 5).

Conclusions

More clinical trials are required to confirm the impact of nitrate on oral communities. However, these findings support the hypothesis that nitrate could be used as an oral health prebiotic. Future studies should investigate whether chlorhexidine-containing mouthwashes could be replaced or complemented by a nitrate-rich diet or nitrate supplementation.

The infant gut microbiota as the cornerstone for future gastrointestinal health

The early postnatal period represents a critical window of time for the establishment and maturation of the human gut microbiota. The gut microbiota undergoes dramatic developmental changes during the first year of life, being influenced by a variety of external factors, with diet being a major player. Indeed, the introduction of complementary feeding provides novel nutritive substrates and triggers a shift from milk-adapted gut microbiota toward an adult-like bacterial composition, which is characterized by an enhancement in diversity and proportions of fiber-degrading bacterial genera like Ruminococcus, Prevotella, Eubacterium, and Bacteroides genera. Inadequate gut microbiota development in early life is frequently associated with concomitant and future adverse health conditions. Thus, understanding the processes that govern initial colonization and establishment of microbes in the gastrointestinal tract is of great importance. This review summarizes the actual understanding of the assembly and development of the microbial community associated with the infant gut, emphasizing the importance of mother-to-infant vertical transmission events as a fundamental arrival route for the first colonizers.

Upper respiratory tract microbiome profiles in SARS-CoV-2 Delta and Omicron infected patients exhibit variant specific patterns and robust prediction of disease groups

IMPORTANCE

The role of the upper respiratory tract (URT) microbiome in predicting lung health has been documented in several studies. The dysbiosis in COVID patients has been associated with disease outcomes by modulating the host immune system. However, although it has been known that different SARS-CoV-2 variants manifest distinct transmissibility and mortality rates in human populations, their effect on the composition and diversity of the URT microbiome has not been studied to date. Unlike the older variant (Delta), the newer variant (Omicron) have become more transmissible with lesser mortality and the symptoms have also changed significantly. Hence, in the present study, we have investigated the change in the URT microbiome associated with Delta and Omicron variants and identified variant-specific signatures that will be useful in the assessment of lung health and can be utilized for nasal probiotic therapy in the future.

Veillonella parvula promotes the proliferation of lung adenocarcinoma through the nucleotide oligomerization domain 2/cellular communication network factor 4/nuclear factor kappa B pathway

Enrichment of Veillonella parvula in the lung microbiota is strongly associated with non-small cell lung cancer (NSCLC) and induces the progression of lung adenocarcinoma in vivo, but its actual role and mechanism remain unexplored. This study analyzed the correlation between NSCLC and V. parvula abundance based on 16 s rRNA sequencing results. The effects of V. parvula on the progression of lung adenocarcinoma were observed in vivo and in vitro using a C57 bl/6j mouse tumor-bearing model, a bacterial cell co-culture model, combined with transcriptome sequencing, and a TCGA database to explore and validate the growth promotion of lung adenocarcinoma by V. parvula and its molecular mechanism. 16 s rRNA sequencing revealed that V. parvula was significantly enriched in lung adenocarcinoma. In vivo, V. parvula promoted the growth of lung adenocarcinoma in mice by suppressing the infiltration of tumor-associated T lymphocytes and peripheral T lymphocytes. It showed a higher affinity for lung adenocarcinoma in vitro and promoted lung adenocarcinoma cell proliferation through adhesion or intracellular invasion. Further analysis of differential gene expression and KEGG enrichment by transcriptome sequencing revealed that V. parvula induced CCN4 expression and activated NOD-like receptor and NF-κB signaling pathway in lung adenocarcinoma cells. Further analysis clarified that V. parvula promoted activation of the NF-κB pathway via Nod2/CCN4 signaling, which promoted lung adenocarcinoma cell proliferation. Thus, V. parvula mediates activation of the Nod2/CCN4/NF-κB signaling pathway to promote non-small cell lung adenocarcinoma progression, thereby providing a potential target for diagnosing and treating lung adenocarcinoma.

Translocation of Oral Microbiota into the Pancreatic Ductal Adenocarcinoma Tumor Microenvironment

Oral dysbiosis has long been associated with pancreatic ductal adenocarcinoma (PDAC). In this work, we explore the relationship between the oral and tumor microbiomes of patients diagnosed with PDAC. Salivary and tumor microbiomes were analyzed using a variety of sequencing methods, resulting in a high prevalence and relative abundance of oral bacteria, particularly Veillonella and Streptococcus, within tumor tissue. The most prevalent and abundant taxon found within both saliva and tumor tissue samples, Veillonella atypica, was cultured from patient saliva, sequenced and annotated, identifying genes that potentially contribute to tumorigenesis. High sequence similarity was observed between sequences recovered from patient matched saliva and tumor tissue, indicating that the taxa found in PDAC tumors may derive from the mouth. These findings may have clinical implications in the care and treatment of patients diagnosed with PDAC.

Identifying keystone species in microbial communities using deep learning

Previous studies suggested that microbial communities harbor keystone species whose removal can cause a dramatic shift in microbiome structure and functioning. Yet, an efficient method to systematically identify keystone species in microbial communities is still lacking. This is mainly due to our limited knowledge of microbial dynamics and the experimental and ethical difficulties of manipulating microbial communities. Here, we propose a Data-driven Keystone species Identification (DKI) framework based on deep learning to resolve this challenge. Our key idea is to implicitly learn the assembly rules of microbial communities from a particular habitat by training a deep learning model using microbiome samples collected from this habitat. The well-trained deep learning model enables us to quantify the community-specific keystoneness of each species in any microbiome sample from this habitat by conducting a thought experiment on species removal. We systematically validated this DKI framework using synthetic data generated from a classical population dynamics model in community ecology. We then applied DKI to analyze human gut, oral microbiome, soil, and coral microbiome data. We found that those taxa with high median keystoneness across different communities display strong community specificity, and many of them have been reported as keystone taxa in literature. The presented DKI framework demonstrates the power of machine learning in tackling a fundamental problem in community ecology, paving the way for the data-driven management of complex microbial communities.

High-Throughput Sequencing Analysis of the Changes in the Salivary Microbiota of Hungarian Young and Adult Subpopulation by an Anthocyanin Chewing Gum and Toothbrush Change

The sour cherry contains anthocyanins, which have bactericide action against some oral bacteria (Klebsiella pneumoniae, Pseudomonas aeruginosa). Sour cherry also has antibiofilm action against Streptococcus mutans, Candida albicans, and Fusobacterium nucleatum. Our earlier research proved that chewing sour cherry anthocyanin gum significantly reduces the amount of human salivary alpha-amylase and Streptococcus mutans levels. The microbiota of a toothbrush affects oral health and regular toothbrush change is recommended. A total of 20 healthy participants were selected for the study. We analysed saliva samples with 16S rRNA sequencing to investigate the effect of 2 weeks (daily three times, after main meals) of chewing sour cherry anthocyanin gum-supplemented by toothbrush change in half of our case-control study cohort-after scaling on human oral microbiota. A more stable and diverse microbiome could be observed after scaling by the anthocyanin gum. Significant differences between groups (NBR: not toothbrush changing; BR: toothbrush changing) were evaluated by log₂ proportion analysis of the most abundant family and genera. The analysis showed that lower level of some Gram-negative anaerobic (Prevotella melaninogenica, Porphyromonas pasteri, Fusobacterium nucleatum subsp. vincentii) and Gram-positive (Rothia mucilaginosa) bacteria could be observed in the case group (BR), accompanied by build-up of health-associated Streptococcal network connections.

Veillonella atypica causing retropharyngeal abscess: A rare case presentation

Veillonella species are obligate anaerobes which are part of the human oral, gut and vaginal microbiota. The genus Veillonella consists of 16 characterized species. Very few infections due to Veillonella atypica have been reported till date. Here we present a case of retropharyngeal abscess due to this organism in a 55-year-old lady.

The Effect of Hydrolyzed and Fermented Arabinoxylan-Oligo Saccharides (AXOS) Intake on the Middle-Term Gut Microbiome Modulation and Its Metabolic Answer

Although fermentation and hydrolyzation are well-known processes to improve the bioavailability of nutrients and enable the fortification with dietary fibers, the effect of such pre-treatments on the prebiotic features of arabinoxylan-oligosaccharides (AXOS) had not been explored. The middle-term in vitro simulation through the Simulator of the Human Intestinal Microbial Ecosystem (SHIME) demonstrated that the feeding with different formulations (namely oat bran, rye bran and wheat bran) containing hydrolyzed AXOS fermented by lactic acid bacteria significantly increased the synthesis of short-chain fatty acids (SCFA) by colon microbiota, with hydrolyzed and fermented rye bran displaying the highest effect. After two weeks from the interruption of intake, SCFA concentrations significantly decreased but remained still significantly higher compared to the original condition. The microbiome was also affected, with a significant abundance increase in Lactobacillaceae taxon after feeding with all fermented and hydrolyzed formulates. Hydrolyzed and fermented rye bran showed the highest changes. The fungal community, even if it had a lower variety compared to bacteria, was also modulated after feeding with AXOS formulations, with an increase in Candida relative abundance and a decrease in Issatchenkia. On the contrary, the intake of non-hydrolyzed and non-fermented wheat bran did not produce relevant changes of relative abundances. After two weeks from intake interruption (wash out period) such changes were mitigated, and the gut microbiome modulated again to a final structure that was more like the original condition. This finding suggests that hydrolyzed AXOS fermented by lactic acid bacteria could have a more powerful prebiotic effect compared to non-hydrolyzed and non-fermented wheat bran, shaping the colon microbiome and its metabolic answer. However, the intake should be continuous to assure persistent effects. Opening a window into the ecological evolutions and plausible underlying mechanisms, the findings reinforce the perspective to explore more in depth the use of hydrolyzed and fermented AXOS as additional ingredient for bread fortification.

Polybetaine-enhanced hybrid ionomer cement shows improved total biological effect with bacterial resistance and cellular stimulation

Hybrid ionomer cements (HICs) are aesthetic polyelectrolyte cements that have been modified with a resin. The setting of HICs occurs by both monomer polymerization and an acid-base reaction. In addition, HICs contain a resin, which is substituted for water. Thus, the competition between the setting reactions and reduced water content inherently limits polysalt formation and, consequently the bioactive interactions. In this study, we explored the effects of polybetaine zwitterionic derivatives (mZMs) on the augmentation of the bioactive response of HICs. The polybetaines were homogenized into an HIC in different proportions (α, β, and γ) at 3% w/v. Following basic characterization, the bioactive response of human dental pulp stem cells (hDPSCs) was evaluated. The augmented release of the principal constituent ions (strontium, silica, and fluoride) from the HIC was observed with the addition of the mZMs. Modification with α-mZM elicited the most favorable bioactive response, namely, increased ion elution, in vitro calcium phosphate precipitation, and excellent biofouling resistance, which deterred the growth of the bridging species of Veillonella. Moreover, α-mZM resulted in a significant increase in the hDPSC response, as confirmed by a significant increase (p < 0.05) in alizarin red staining. The results of mRNA expression tests, performed using periodically refreshed media, showed increased and early peak expression levels for RUNX2, OCN, and OPN in the case of α-mZM. Based on the results of the in vitro experiments, it can be concluded that modification of HICs with polybetaine α-mZM can augment the overall biological response.

Orofacial clefts alter early life oral microbiome maturation towards higher levels of potentially pathogenic species: A prospective observational study

Orofacial clefts (OFC) present different phenotypes with a postnatal challenge for oral microbiota development. In order to investigate the impact of OFC on oral microbiota, smear samples from 15 neonates with OFC and 17 neonates without OFC were collected from two oral niches (tongue, cheek) at two time points, i.e. after birth (T0: Ø3d OFC group; Ø2d control group) and 4-5 weeks later (T1: Ø32d OFC group; Ø31d control group). Subsequently, the samples were analyzed using next-generation sequencing. We detected a significant increase of alpha diversity and anaerobic and Gram-negative species from T0 to T1 in both groups. Further, we found that at T1 OFC neonates presented a significantly lower alpha diversity (lowest values for high cleft severity) and significantly higher levels of Enterobacteriaceae (Citrobacter, Enterobacter, Escherichia-Shigella, Klebsiella), Enterococcus, Bifidobacterium, Corynebacterium, Lactocaseibacillus, Staphylococcus, Acinetobacter and Lawsonella compared to controls. Notably, neonates with unilateral and bilateral cleft lip and palate (UCLP/BCLP) presented similarities in beta diversity and a mixture with skin microbiota. However, significant differences were seen in neonates with cleft palate only compared to UCLP/BCLP with higher levels of anaerobic species. Our findings revealed an influence of OFC as well as cleft phenotype and severity on postnatal oral microbiota maturation.

Oral microbes and the formation of cerebral abscesses: A single-centre retrospective study

OBJECTIVE

Intracranial abscesses are relatively uncommon, but can result in significant mortality and morbidity. Whilst many potential causes of brain abscesses are recognised, in many cases the origin of infection remains clinically unidentified. Our objective was to investigate the role of bacteria found in the oral cavity in the development of brain abscesses.

METHODS

A retrospective analysis was performed using data from 87 patients admitted to a single UK neurosurgical unit with brain abscesses over a 16-year period. Using microbiological data obtained from abscess sampling and peripheral cultures, species of bacteria were categorised in patients where no primary source of infection was identified (NSI) for their brain abscess (n = 52), or where an infective source (ISI) was identified. The microbiological data was then screened to identify common oral bacteria in each group.

RESULTS

Brain abscesses from the ISI group (n = 35) demonstrated a significantly lower preponderance of oral bacteria (n = 8), than the NSI group (n = 29) (p < 0.05). Brain abscesses from the NSI group also had significantly higher counts of Streptococcus anginosus compared to ISI (p < 0.05), with brain abscesses being most common in the frontal and parietal lobes for both ISI and NSI.

CONCLUSIONS

These findings suggest that the oral cavity could be considered as a source of occult infection in cases of brain abscess where no clear cause has been identified. Future studies should include oral screening and microbiome analysis to better understand the mechanisms involved and develop approaches for prevention.

CLINICAL SIGNIFICANCE STATEMENT

Oral bacteria may be an under-recognised cause of brain abscesses. Careful review of oral health in brain abscess patients may help establish causation, particularly in patients with no cause for their abscess identified. Good levels of oral health may help prevent the development of brain abscesses in some individuals.

A Co-Association of Streptococcus mutans and Veillonella parvula/dispar in Root Caries Patients and In Vitro Biofilms

Root caries in geriatric patients is a growing problem as more people are maintaining their natural teeth into advanced age. We determined the levels of various bacterial species previously implicated in root caries disease or health using quantitative real-time PCR in a pilot study of 7 patients with 1 to 4 root caries lesions per person. Levels of 12 different species on diseased roots compared to healthy (contralateral control) roots were measured. Four species were found at significantly higher levels on diseased roots (Streptococcus mutans, Veillonella parvula/dispar, Actinomyces naeslundii/viscosus, and Capnocytophaga granulosa) compared across all plaque samples. The level of colonization by these species varied dramatically (up to 1,000-fold) between patients, indicating different patients have different bacteria contributing to root caries disease. Neither of the two species previously reported to correlate with healthy roots (C. granulosa and Delftia acidovorans) showed statistically significant protective roles in our population, although D. acidovorans showed a trend toward higher levels on healthy teeth (P = 0.08). There was a significant positive correlation between higher levels of S. mutans and V. parvula/dispar on the same diseased teeth. In vitro mixed biofilm studies demonstrated that co-culturing S. mutans and V. parvula leads to a 50 to 150% increase in sucrose-dependent biofilm mass compared to S. mutans alone, depending on the growth conditions, while V. parvula alone did not form in vitro biofilms. The presence of V. parvula also decreased the acidification of S. mutans biofilms when grown in artificial saliva and enhanced the health of mixed biofilms.

Oral Microbiome and Dental Caries Development

Dental caries remains the most prevalent oral disease worldwide. The development of dental caries is highly associated with the microbiota in the oral cavity. Microbiological research of dental caries has been conducted for over a century, with conventional culture-based methods and targeted molecular methods being used in order to identify the microorganisms related to dental caries. These methods' major limitation is that they can identify only part of the culturable microorganisms in the oral cavity. Introducing sequencing-based technology and bioinformatics analysis has boosted oral microbiome research and greatly expanded the understanding of complex oral microbiology. With the continuing revolution of molecular technologies and the accumulated sequence data of the oral microbiome, researchers have realized that microbial composition alone may be insufficient to uncover the relationship between caries and the microbiome. Most updated evidence has coupled metagenomics with transcriptomics and metabolomics techniques in order to comprehensively understand the microbial contribution to dental caries. Therefore, the objective of this article is to give an overview of the research of the oral microbiome and the development of dental caries. This article reviews the classical concepts of the microbiological aspect of dental caries and updates the knowledge of caries microbiology with the results of current studies on the oral microbiome. This paper also provides an update on the caries etiological theory, the microorganisms related to caries development, and the shifts in the microbiome in dental caries development.

Comparison of antibacterial and antibiofilm activity of bioactive glass compounds S53P4 and 45S5

Background

Bone loss and deformation due to damage caused by injury or recurrent invasive infections presents a major clinical obstacle. While bone substitute biomaterials promote osseous tissue regeneration, their application in sites complicated by microbial infections such as osteomyelitis, is limited. Bioactive glass biomaterials (Bioglass) have been shown to have efficient mechanisms of repairing the integrity of bone, while inhibiting growth of a range of bacterial strains. There are several commercially available bioactive glass compounds, each with a unique chemical composition. One compound in particular, S53P4, has demonstrated antimicrobial effects in previous studies but the antimicrobial activity of the parent compound 45S5 has not been investigated.

Results

To assess whether antimicrobial activity is common among bioglass compounds, 45S5-the parent compound, was evaluated in comparison to S53P4 for antibacterial and antibiofilm effects against multiple strains of aerobic and anaerobic bacteria associated with various types of osteomyelitis. Experiments of antimicrobial effects in liquid cultures demonstrated that both compounds were antimicrobial against various microbial genera including S. gordonii, V. parvula, P. aeruginosa and MRSA; particles of the smallest size (32–125 µm) invariably showed the most robust antimicrobial capabilities. When employed against biofilms ecological biofilms grown on hydroxyapatite, 45S5 particles produced a stronger reduction in biofilm mass compared to S53P4 particles when considering small particle ranges.

Conclusion

We found that 45S5 seems to be as effective as S53P4 and possibly even more capable of limiting bacterial infections. The efficacy of bioactive glass was not limited to inhibition of planktonic growth, as it also extended to bacterial biofilms. The increased antibacterial activity of 45S5 compared to S53P4 is true for a variety of size ranges.

Mother-infant transmission of human microbiota

Humans are colonised by a highly adapted microbiota with coevolved functions that promote human health, development and disease resistance. Acquisition and assembly of the microbiota start at birth and recent evidence suggests that it coincides with, and informs, immune system development and regulation in the rapidly growing infant. Several large-scale studies have identified Bifidobacterium and Bacteroides species maternally transmitted to infants, many of which are capable of colonising over the longer term. Disruption of maternal transmission by caesarean section and antibiotic exposure around birth is associated with a higher incidence of pathogen colonisation and immune-related disorders in children. In this review, we discuss key maternally transmitted bacterial species, their sources and their potential role in shaping immune development. Maternal transmission of gut bacteria provides a microbial 'starter kit' for infants which promotes healthy growth and disease resistance. Optimising and nurturing this under-appreciated form of kinship should be considered as a priority.

The Composition and Functional Capacities of Saliva Microbiota Differ Between Children With Low and High Sweet Treat Consumption

Excess sugar consumption—common in youth—is associated with poor health. Evidence on the relationship between sugar consumption and the oral microbiome, however, remains scarce and inconclusive. We explored whether the diversity, composition, and functional capacities of saliva microbiota differ based on the consumption of select sugary foods and drinks (“sweet treats”). Using 16S rRNA gene sequencing, we characterized saliva microbiota from 11 to 13-year-old children who participated in the Finnish Health in Teens (Fin-HIT) cohort study. The sample comprised children in the lowest (n = 227) and highest (n = 226) tertiles of sweet treat consumption. We compared differences in the alpha diversity (Shannon, inverse Simpson, and Chao1 indices), beta diversity (principal coordinates analysis based on Bray–Curtis dissimilarity), and abundance (differentially abundant operational taxonomic units (OTUs) at the genus level) between these low and high consumption groups. We performed PICRUSt2 to predict the metabolic pathways of microbial communities. No differences emerged in the alpha diversity between low and high sweet treat consumption, whereas the beta diversity differed between groups (p = 0.001). The abundance of several genera such as Streptococcus, Prevotella, Veillonella, and Selenomonas was higher in the high consumption group compared with the low consumption group following false discovery rate correction (p < 0.05). Children with high sweet treat consumption exhibited higher proportions of nitrate reduction IV and gondoate biosynthesis pathways compared with the low consumption group (p < 0.05). To conclude, sweet treat consumption shapes saliva microbiota. Children who consume a high level of sweet treats exhibited different compositions and metabolic pathways compared with children who consume low levels of sweet treats. Our findings reveal novel insights into the relationship between sugary diets and oral microbiota.

The Oral Microbiota: Community Composition, Influencing Factors, Pathogenesis, and Interventions

The human oral cavity provides a habitat for oral microbial communities. The complexity of its anatomical structure, its connectivity to the outside, and its moist environment contribute to the complexity and ecological site specificity of the microbiome colonized therein. Complex endogenous and exogenous factors affect the occurrence and development of the oral microbiota, and maintain it in a dynamic balance. The dysbiotic state, in which the microbial composition is altered and the microecological balance between host and microorganisms is disturbed, can lead to oral and even systemic diseases. In this review, we discuss the current research on the composition of the oral microbiota, the factors influencing it, and its relationships with common oral diseases. We focus on the specificity of the microbiota at different niches in the oral cavity, the communities of the oral microbiome, the mycobiome, and the virome within oral biofilms, and interventions targeting oral pathogens associated with disease. With these data, we aim to extend our understanding of oral microorganisms and provide new ideas for the clinical management of infectious oral diseases.