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The L-(+)-lactate dehydrogenase from Rothia dentocariosa strain 17931 is activated by fructose 1,6-diphosphate and inhibited by adenosine 5'-triphosphate. The enzyme has a molecular weight of 120,000. In these respects, it resembles the lactate dehydrogenase of Actinomyces viscosus.
An extracellular polysaccharide identified as a levan has been isolated from Rothia dentocariosa, strain 477 serotype 2. The levan produced by strain 477 has been found to activate the complement cascade in the absence of specific antibodies. This activation was found to be cytotoxic for human gingival cells in tissue culture.
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Gluten are proline- and glutamine-rich proteins present in wheat, barley, and rye and contain the immunogenic sequences that drive celiac disease (CD). Rothia mucilaginosa, an oral microbial colonizer, can cleave these gluten epitopes. The aim was to isolate and identify the enzymes and evaluate their potential as novel enzyme therapeutics for CD. The membrane-associated R. mucilaginosa proteins were extracted and separated by DEAE chromatography. Enzyme activities were monitored with paranitroanilide-derivatized and fluorescence resonance energy transfer (FRET) peptide substrates, and by gliadin zymography. Epitope elimination was determined in R5 and G12 ELISAs. The gliadin-degrading Rothia enzymes were identified by LC-ESI-MS/MS as hypothetical proteins ROTMU0001_0241 (C6R5V9_9MICC), ROTMU0001_0243 (C6R5W1_9MICC), and ROTMU0001_240 (C6R5V8_9MICC). A search with the Basic Local Alignment Search Tool revealed that these are subtilisin-like serine proteases belonging to the peptidase S8 family. Alignment of the major Rothia subtilisins indicated that all contain the catalytic triad with Asp (D), His (H), and Ser (S) in the D-H-S order. They cleaved succinyl-Ala-Ala-Pro-Phe-paranitroanilide, a substrate for subtilisin with Pro in the P2 position, as in Tyr-Pro-Gln and Leu-Pro-Tyr in gluten, which are also cleaved. Consistently, FRET substrates of gliadin immunogenic epitopes comprising Xaa-Pro-Xaa motives were rapidly hydrolyzed. The Rothia subtilisins and two subtilisins from Bacillus licheniformis, subtilisin A and the food-grade Nattokinase, efficiently degraded the immunogenic gliadin-derived 33-mer peptide and the immunodominant epitopes recognized by the R5 and G12 antibodies. This study identified Rothia and food-grade Bacillus subtilisins as promising new candidates for enzyme therapeutics in CD.
AIMS/HYPOTHESIS: The breastmilk microbiome plays a crucial role in gut microbial colonisation and immune development, but little is known about how it is influenced by type 1 diabetes. METHODS: We conducted a longitudinal 16S rRNA gene sequencing study of milk from women with type 1 diabetes (n=69 pregnancies; 174 samples) and women who did not have type 1 diabetes (n=49 pregnancies; 123 samples), collected at seven timepoints from birth to 15 months postpartum. Alpha diversity (richness, inverse Simpson evenness) was analysed by generalised linear mixed models, beta diversity was analysed by Bray-Curtis dissimilarities and PERMANOVA, and differential abundance was analysed by limma. Additionally, we examined associations with maternal genetic risk score (GRS), maternal HLA type, glycaemic management (HbA1c) and breastmilk secretory IgA (sIgA), and performed a parallel analysis for the infant stool microbiome. RESULTS: A significant interaction between type 1 diabetes status and timepoint was observed for alpha diversity, both richness (p=0.01) and inverse Simpson diversity (p=0.003), indicating distinct temporal trajectories between women with and without type 1 diabetes. In those without type 1 diabetes, richness increased significantly between birth and 1 week postpartum, but this early increase was delayed in women with type 1 diabetes to between 1 week and 3 months postpartum (p=0.002). Beta diversity analysis revealed earlier and more extensive compositional shifts in women without type 1 diabetes compared to those with type 1 diabetes. These differences persisted after adjusting for Caesarean delivery, BMI, parity and infant sex, and were not attributable to a delay in initiating breastfeeding. Taxa with delayed enrichment in women with type 1 diabetes included Streptococcus spp. and Rothia mucilaginosa, which metabolise human milk oligosaccharides to short-chain fatty acids to promote development of the infant's gut barrier and immune system. Maternal GRS, HLA, HbA1c or sIgA were not associated with milk microbiota diversity trajectories. In infant stool samples, alpha diversity did not differ between exposure groups, and showed no evidence of delayed maturation. Beta diversity revealed an early compositional shift between birth and 1 week postpartum only in infants born to women without type 1 diabetes. Similarly, significant taxonomic changes between birth and 1 week postpartum were detected only in infants born to women without type 1 diabetes, but with some taxa differing between exposure groups at 1 week. CONCLUSIONS/INTERPRETATION: Maternal type 1 diabetes is associated with delayed early maturation of the breastmilk microbiome. Early compositional differences in microbiota restructuring were also observed in the infant gut, partially mirroring the pattern in the milk microbiome; however, sustained differences in infant gut microbiota diversity were not detected. Further investigation could determine whether these changes affect development of the infant's gut and immune system.
INTRODUCTION AND AIMS: The oral microbiome has been increasingly linked to systemic inflammation and immune dysregulation, but whether specific oral bacteria causally contribute to inflammatory skin diseases remains unclear due to confounding and reverse causation. This study aimed to assess the causal effects of 43 oral microbiota taxa on the risk of five inflammatory skin diseases using a Mendelian randomization (MR) approach. METHODS: We performed a two-sample MR analysis using genetic instruments for oral microbiota derived from publicly available genome-wide association studies and outcome data from the FinnGen consortium. Causal effects of oral taxa on systemic lupus erythematosus, vitiligo, pemphigus, localized scleroderma, and dermatitis herpetiformis were estimated. The inverse-variance weighted method served as the primary analysis, complemented by sensitivity analyses to evaluate horizontal pleiotropy, heterogeneity, and reverse causality. RESULTS: MR analyses identified several putative causal associations between oral microbiota and inflammatory skin diseases. Genus Granulicatella and an unknown Streptococcus species (ASV0009) showed causal effects on systemic lupus erythematosus. Family Lachnospiraceae_[XIV] and an unknown Rothia species (ASV0016) were associated with vitiligo. Five oral microbiota taxa demonstrated causal associations with pemphigus. Actinomyces species micronuciformis was linked to localized scleroderma. Order Fusobacteriales and an unknown Neisseria species (ASV0004) were associated with dermatitis herpetiformis. No significant heterogeneity or horizontal pleiotropy was detected in sensitivity analyses. CONCLUSION: This MR study provides genetic evidence supporting a causal role of specific oral bacteria in the development of several inflammatory skin diseases, highlighting the oral microbiome as a potential contributor to cutaneous autoimmunity and inflammation. CLINICAL RELEVANCE: Our findings highlight the putative role of the oral microbiome as a plausible candidate for mechanistic and clinical investigations into the prevention or adjunctive management of selected inflammatory skin diseases. However, oral hygiene improvement, targeted antimicrobials, and other microbiota-directed interventions were not directly tested in this MR study and remain hypothetical strategies requiring validation in experimental and clinical studies.
OBJECTIVES: Traditional periodontal therapy primarily focuses on bacterial biofilm control; however, recent evidence also suggests a critical role for the oral mycobiome. This study evaluated the clinical and ecological impact of a novel mouthwash formulation containing hyaluronic acid (HA), hydrogen peroxide (H2O2), and glycine on periodontal patients METHODS: This prospective, randomized split-mouth trial included 13 adult participants with periodontitis treated with HA-H2O2-glycine formula (BMG0703A) used twice a day for seven days. Subgingival plaque samples were collected from periodontal pocket and healthy control sites at baseline (T0) and one-week post-treatment (T1). Microbial and fungal communities were characterized using Next-Generation Sequencing (NGS) of the 16S rRNA and ITS2 regions. Linear Mixed Models (LMM) and Spearman correlation were used to assess taxonomic shifts and cross-kingdom relationships. RESULTS: Sequencing revealed a promising ecological shift: the bacteriome shifted from anaerobic dominance (Olsenella, Peptostreptococcus) toward a health-associated aerobic profile, with Rothia near-doubling (11.91% to 22.68%). The mycobiome underwent a "normalization" effect: Candida abundance decreased significantly (22.8% to 9.1%), while fungal Shannon diversity in pockets returned to healthy-site levels. Inter-kingdom analysis identified antagonistic relationships between expanding commensal bacteria and opportunistic fungi, suggesting that the intervention may help re-establish a protective bacterial niche. CONCLUSIONS: The HA-H2O2-glycine formulation seems to facilitate a rapid, cross-kingdom modulation of the subgingival niche. By reducing anaerobic pathogens and normalizing the mycobiome it appear to induce short-term changes, suggesting potential as adjunctive strategy in periodontal management. CLINICAL SIGNIFICANCE: The present work underlines the possible cross-Kingdom effects of a novel compound.
Toxoplasma gondii infection is associated with intestinal microbiome disruption, but its effects on genome-resolved bacterial populations, the gut virome, and bacteriome-virome relationships remain poorly understood. Using previously generated shotgun metagenomic datasets from 36 intestinal samples collected from 18 Sprague-Dawley rats across control, acute, and chronic infection groups, we reconstructed 294 quality-filtered, non-redundant bacterial metagenome-assembled genomes (MAGs) and identified 899 medium-to-high-quality viral operational taxonomic units (vOTUs) from assembled metagenomic contigs. Infection was associated with reduced bacterial richness in the small intestine during both acute and chronic stages and lower Shannon diversity during chronic infection. In contrast, large-intestinal α-diversity remained stable despite significant compositional reorganization. Taxonomic changes included increased Lactobacillus intestinalis, Limosilactobacillus reuteri, and Prevotella sp900547005, together with decreased Rothia sp002492045 and Akkermansia muciniphila. Functional profiling revealed region- and stage-specific changes in predicted bacterial metabolic potential, including reduced energy-related pathways and carbohydrate-active enzyme abundance. The virome also showed significant compositional changes in both intestinal regions. Quimbyviridae and Podoviridae_crAss-like viruses decreased in the small intestine during chronic infection, while Quimbyviridae, Flandersviridae, and Podoviridae_crAss-like viruses showed stage-specific decreases in the large intestine. Predicted bacterial hosts were assigned to 48.39% of vOTUs, with Lachnospiraceae and Ruminococcaceae being the most frequently linked families. Trans-kingdom networks further revealed region-specific positive and negative abundance correlations between bacterial and viral taxa. These findings extend previous microbiota-metabolome observations by integrating genome-resolved bacteriome analysis with contig-based virome profiling, providing a foundation for future mechanistic studies of toxoplasmosis-associated microbiome remodeling.
The human oral and gut microbiota are the 4 largest microbial communities in the body and play crucial roles in maintaining homeostasis and influencing disease. Observational studies have suggested links between these microbiota and bone neoplasm-related phenotypes, but establishing causality has been challenging due to confounding factors and reverse causality. We conducted a bidirectional, 2-sample Mendelian randomization (MR) study to investigate evidence consistent with a potential causal association between the saliva and gut microbiota and various bone neoplasm-related phenotypes. Genetic instruments for saliva and gut microbiota were sourced from large genome-wide association studies. Inverse variance weighted was the primary MR method, supplemented by 4 other MR techniques. Sensitivity analyses, including MR-Egger regression, were performed to assess pleiotropy and heterogeneity. In the forward MR analysis, Veillonella parvula from the saliva microbiota was associated with a decreased risk of bone and connective tissue neoplasms (β: -0.236, 95% CI: [-0.275, -0.197], P = 8.20E-33). MR analyses identified genetically predicted associations between several microbial taxa and bone neoplasm-related phenotypes. Reverse MR analyses showed that genetic liability to bone neoplasm-related phenotypes was associated with variation in the composition of the oral (e.g., Order Bacteroidales, Rothia mucilaginosa) and gut microbiota (e.g., Class Methanobacteria, Genus Eubacterium oxidoreducens group). Sensitivity analyses confirmed the robustness of these findings, as no statistical evidence of substantial heterogeneity or directional horizontal pleiotropy was detected. This study provides genetic evidence supporting a bidirectional causal relationship between specific saliva and gut microbiota and bone neoplasm-related phenotypes. Our findings identify several microbial taxa as potential candidates for future biomarker development and therapeutic investigation in bone neoplasm-related phenotypes. However, these genetically informed associations require further mechanistic, experimental, and prospective clinical validation before clinical application.
Samples of subgingival plaque were collected from periodontal patients receiving two different tetracycline treatment regimens following conventional periodontal therapy. Four patients had received an oral dose of 1000 mg/day for 2 weeks and nine had received 1000 mg/day for 1 week followed by 250 mg/day for extended time periods. The latter regimen is similar so that commonly prescribed for the chronic skin disease, acne vulgaris. Taxonomic characterization of plaque isolates indicated that the predominant organisms cultured from both treatment groups were species of Streptococcus and the branching, filamentous Gram-positive rods, Actinomyces and Rothia. A much greater microbial complexity was observed among the flora isolated from patients taking 250 mg/day. The latter group harbored many of the fastidious Gram-negative organisms presently implicated in the etiology of periodontal disease. All bacterial strains isolated were tested for resistance to tetracycline by replica-plating cultures on an agar medium containing two-fold dilutions of the antibiotic. Streptococcus, Veillonella and Neisseria were the bacterial genera found to be consistently resistant to tetracycline, with minimum inhibitory concentrations as high as 128 micrograms/ml. Among the Actinomyces, selection for antibiotic resistance was common only within a single species, A. odontolyticus. However, A viscosus strains isolated at 54% of the subgingival flora from one patient did demonstrate an intermediate resistance level, growing on concentrations up to 8 micrograms/ml. Tetracycline resistance was shown by a variety of Gram-negative rods isolated from the low dosage group. Although a minimum number of patients were studied, extensive microbial analyses of the predominating subgingival bacteria indicated that the goal of tetracycline therapy was achieved during the 2-week therapy period at 1000 mg/day.
Samples of apical plaque were taken by means of an anaerobic gas-flushed syringe from 21 sites in eight patients. The samples were anaerobically dispersed, diluted and plated and incubated in an atmosphere of 80% N2, 10% H2 and 10% CO2 for 7-21 days. All colonies on plates containing 20-50 isolates were picked, repeatedly restreaked, characterized and identified where possible by a probabilistic computer identification program. The sites were divided into four groups on the basis of clinical features. The significance of differences between bacterial populations in the groups was determined by the Kruskal Wallis and Mann-Whitney U tests, while the Spearman rank correlation coefficient was used to determine the rank correlation of clinical features of diseases and microbial species. The subgingival microbiota in advanced destructive sites was predominated by Gram-negative rods. The microbiota of two young adult patients with generalized extensive bone loss, extensive clinical inflammation and suppuration was dominated by Bacteroides asaccharolyticus and an organism with characteristics consistent with Actinobacillus actinomycetemcomitans. The predominant cultivable microbiota in two patients with extensive bone loss but minimal clinical inflammation was predominated by Bacteroides melaninogenicus ss intermedius and Eikenella corrodens in one patient and E. corrodens and a slow growing fusiform-shaped Bacteroides in a second patient. A third group of four patients demonstrated moderate levels of clinical inflammation and evidence of continued bone loss in the last year. Predominant organisms in this group were more heterogeneous and included B. asaccharolyticus, Fusobacterium nucleatum, the "fusiform" Bacteroides and anaerobic vibrios. Sites with minimal disease in the patients revealed higher proportions of Gram-positive organisms including Rothia dentocariosa, Actinomyces naeslundii and Actinomyces viscosus. A positive rank correlation could be detected between clinical inflammation including suppuration and B. asaccharolyticus and a negative rank correlation between inflammation and E. corrodens.
This prospective cohort study investigated the longitudinal development of the salivary bacteriome, virome, and metabolome during early infancy. We assessed the associations between oral bacteria, viruses, and metabolites from 10 mother-infant dyads, with oral samples collected at 1 and 2 years of age. Forty saliva and plaque samples underwent untargeted metabolomic analysis, and infant saliva samples underwent metagenomic sequencing. Maternal salivary and plaque metabolomic profiles remained largely stable, whereas infant profiles were clearly separated from maternal profiles and changed with age. Notably, infant dental plaque metabolism underwent more substantial changes from year 1 to year 2 than saliva, with age-dependent metabolite shifts mainly involving energy, amino acid, nucleotide, and lipid metabolic pathways. Our findings also revealed significant developmental shifts in salivary bacteriome, virome, and functional pathway profiles during early childhood. The most abundant oral bacteria in early life, comprising over 75% of total abundance, included Veillonella, Streptococcus, Rothia, Prevotella, Neisseria, and Actinomyces species. While human viruses like Roseolovirus were detected, bacteriophages constituted the majority of the virome. Comparing infants at year 1 and year 2, we identified differentially abundant bacteria, viruses, metabolic functional pathways, and specific metabolites. We observed associations between bacteria and viruses, noting that these cross-kingdom relationships attenuated as infants grew. The study results underscore the complex and dynamic development of the oral microbiome, virome, and metabolome during early childhood.IMPORTANCEThe human oral cavity undergoes substantial microbial and metabolic development during early childhood, yet the temporal changes in the infant oral ecosystem remain incompletely understood. In this study, we longitudinally profiled the salivary metabolome, bacteriome, and virome of infants at 1 and 2 years of age. We demonstrated that the infant oral metabolome undergoes substantial developmental shifts, particularly in pathways related to energy, amino acid, and lipid metabolism; whereas maternal metabolic profiles remained stable over the same period. Furthermore, our results revealed the dynamic assembly of infant salivary virome and bacteriome and their associations with the functional pathways and metabolites. These findings provide new insights into the complex and dynamic development of the oral microbiome, virome, and metabolome in early infancy.