Environment-Specific Probiotic Supernatants Modify the Metabolic Activity and Survival of Streptococcus mutans in vitro

Metagenomic analysis of the intestinal microbiome reveals the potential mechanism involved in Bacillus amyloliquefaciens in treating schistosomiasis japonica in mice

Schistosomiasis japonica is one of the neglected tropical diseases characterized by chronic hepatic, intestinal granulomatous inflammation and fibrosis, as well as dysbiosis of intestinal microbiome. Previously, the probiotic Bacillus amyloliquefaciens has been shown to alleviate the pathological injuries in mice infected with Schistosoma japonicum by improving the disturbance of the intestinal microbiota. However, the underlying mechanisms involved in this process remain unclear. In this study, metagenomics sequencing and functional analysis were employed to investigate the differential changes in taxonomic composition and functional genes of the intestinal microbiome in S. japonicum-infected mice treated with B. amyloliquefaciens. The results revealed that intervention with B. amyloliquefaciens altered the taxonomic composition of the intestinal microbiota at the species level in infected mice and significantly increased the abundance of beneficial bacteria. Moreover, the abundance of predicted genes in the intestinal microbiome was also significantly changed, and the abundance of xfp/xpk and genes translated to urease was significantly restored. Further analysis showed that Limosilactobacillus reuteri was positively correlated with several KEGG Orthology (KO) genes and metabolic reactions, which might play important roles in alleviating the pathological symptoms caused by S. japonicum infection, indicating that it has the potential to function as another effective therapeutic agent for schistosomiasis. These data suggested that treatment of murine schistosomiasis japonica by B. amyloliquefaciens might be induced by alterations in the taxonomic composition and functional gene of the intestinal microbiome in mice. We hope this study will provide adjuvant strategies and methods for the early prevention and treatment of schistosomiasis japonica.

IMPORTANCE

Targeted interventions of probiotics on gut microbiome were used to explore the mechanism of alleviating schistosomiasis japonica. Through metagenomic analysis, there were significant changes in the composition of gut microbiota in mice infected with Schistosoma japonicum and significant increase in the abundance of beneficial bacteria after the intervention of Bacillus amyloliquefaciens. At the same time, the abundance of functional genes was found to change significantly. The abundance of genes related to urease metabolism and xfp/xpk related to D-erythrose 4-phosphate production was significantly restored, highlighting the importance of Limosilactobacillus reuteri in the recovery and abundance of predicted genes of the gut microbiome. These results indicated potential regulatory mechanism between the gene function of gut microbiome and host immune response. Our research lays the foundation for elucidating the regulatory mechanism of probiotic intervention in alleviating schistosomiasis japonica, and provides potential adjuvant treatment strategies for early prevention and treatment of schistosomiasis japonica.

Horizon scanning the application of probiotics for wildlife

The provision of probiotics benefits the health of a wide range of organisms, from humans to animals and plants. Probiotics can enhance stress resilience of endangered organisms, many of which are critically threatened by anthropogenic impacts. The use of so-called 'probiotics for wildlife' is a nascent application, and the field needs to reflect on standards for its development, testing, validation, risk assessment, and deployment. Here, we identify the main challenges of this emerging intervention and provide a roadmap to validate the effectiveness of wildlife probiotics. We cover the essential use of inert negative controls in trials and the investigation of the probiotic mechanisms of action. We also suggest alternative microbial therapies that could be tested in parallel with the probiotic application. Our recommendations align approaches used for humans, aquaculture, and plants to the emerging concept and use of probiotics for wildlife.

Limosilactobacillus reuteri inhibits the acid tolerance response in oral bacteria

Probiotic bacteria show promising results in prevention of the biofilm-mediated disease caries, but the mechanisms are not fully understood. The acid tolerance response (ATR) allows biofilm bacteria to survive and metabolize at low pH resulting from microbial carbohydrate fermentation. We have studied the effect of probiotic strains: Limosilactobacillus reuteri and Lacticaseibacillus rhamnosus on ATR induction in common oral bacteria. Communities of L. reuteri ATCC PTA5289 and Streptoccus gordonii, Streptococcus oralis, Streptococcus mutans or Actinomyces naeslundii in the initial stages of biofilm formation were exposed to pH 5.5 to allow ATR induction, followed by a low pH challenge. Acid tolerance was evaluated as viable cells after staining with LIVE/DEAD®BacLight™. The presence of L. reuteri ATCC PTA5289 caused a significant reduction in acid tolerance in all strains except S. oralis. When S. mutans was used as a model organism to study the effects of additional probiotic strains (L. reuteri SD2112, L. reuteri DSM17938 or L. rhamnosus GG) as well as L. reuteri ATCC PTA5289 supernatant on ATR development, neither the other probiotic strains nor supernatants showed any effect. The presence of L. reuteri ATCC PTA5289 during ATR induction led to down-regulation of three key genes involved in tolerance of acid stress (luxS, brpA and ldh) in Streptococci. These data suggest that live cells of probiotic L. reuteri ATCC PTA5289 can interfere with ATR development in common oral bacteria and specific strains of L. reuteri may thus have a role in caries prevention by inhibiting development of an acid-tolerant biofilm microbiota.

Glycerol strengthens probiotic effect of Limosilactobacillus reuteri in oral biofilms: a synergistic synbiotic approach

Both in vitro and in vivo studies have shown that the probiotic Limosilactobacillus reuteri can improve oral health. L. reuteri species are known to produce the antimicrobial 'reuterin' from glycerol. In order to further increase its antimicrobial activity, this study evaluated the effect of the combined use of glycerol and Limosilactobacillus reuteri (ATCC PTA 5289) in view of using a synergistic synbiotic over a probiotic. An antagonistic agar growth and a multispecies biofilm model showed that the antimicrobial potential of the probiotic was significantly enhanced against periodontal pathobionts and anaerobic commensals when supplemented with glycerol. Synbiotic biofilms also showed a significant reduction in inflammatory expression of human oral keratinocytes (HOK-18A), but only when the keratinocytes were preincubated with the probiotic. Probiotic preincubation of keratinocytes or probiotic- and synbiotic treatment of biofilms alone were insufficient to significantly reduce inflammatory expression. Overall, this study shows that combining glycerol with the probiotic L. reuteri into a synergistic synbiotic can greatly improve the effectiveness of the latter. One sentence summary: The use of a synbiotic formulation of Limosilactobacillus reuteri with glycerol over the probiotic improves antimicrobial effects and reduced inflammatory response to oral biofilms. This article is protected by copyright. All rights reserved.

Arginine-induced metabolomic perturbation in Streptococcus mutans

Background

Streptococcus mutans is a major pathogen responsible for dental caries. Arginine is a promising potential caries preventive agent which can inhibit the growth of S. mutans. However, the mechanism whereby arginine inhibits S. mutans growth remains unclear.

Aim

To assess the impact of arginine-induced metabolomic perturbations on S. mutans under biofilm conditions.

Methods

We identified 5,933 and 7,413 ions in positive (ESI+) and negative (ESI-) electrospray ion modes, respectively, with a total of 11.05% and 11.58% differential ions subsequently detected in two respective modes. Further analyses of these metabolites led to identification of 8 and 22 metabolic pathways that were affected by arginine treatment in ESI+ and ESI- modes.,

Results

Once or twice daily treatments of S. mutans biofilms with arginine resulted in reductions in biofilm biomass. Significant reductions in EPS production were observed following twice daily arginine treatments. Identified metabolites that were significantly differentially abundant following arginine treatment were associated with glycolysis metabolism, amino sugar and nucleotide sugar metabolism, and peptidoglycan synthesis.

Conclusions

Arginine can reduce S. mutans biofilm growth and acid production by inhibiting glycolysis, amino sugar and nucleotide sugar metabolism, and peptidoglycan synthesis.

The role of yogurt enriched with lactobacillus rhamnosus GG culture in dental caries prevention

Introduction/Objective. Contemporary tendencies suggest that probiotics can significantly reduce the prevalence of caries in children, so it can be considered that they have a positive effect on general and oral health. Lactobacillus rhamnosus GG (LGG) is a probiotic culture of particular importance in preventive dentistry. The aim was to assess the effects of consumption of probiotic strain Lactobacillus rhamnosus GG on the dental plaque accumulation in children with mixed dentition. Methods. Research included 90 children with mixed dentition (5-12 years old). First study group consumed 200 ml of Lactobacillus rhamnosus GG-enriched yogurt (B-Activ LGG, Dukat) daily for a period of 14 days, while the remaining 30 formed the second study group who consumed 200 ml of yogurt (Jogurt 1,5% milk fat, Imlek) with manually added powder from probiotic capsule (Wayaforte LGG capsule, Medis) daily for14 days. The control group consisted of 30 children who had regular diet during examination period. Silness-L?e plaque index and saliva pH (pH-Fix-0-14, Macherey-Nagel) were determined at baseline and also upon intervention completion. Results. An increase in pH values was observed in both study groups. In general sample, there is a significant decrease of mean plaque index values (p ? 0.001). Both study groups had significant decrease of mean plaque index values on the baseline and after 14 days consumption of yogurt. In the control group the number of subjects with decrease plaque index values did not correlate and no association was found. Conclusion. Consistent consumption of LGG culture-enriched yogurt inhibits dental film accumulation and promotes saliva pH increase in children with mixed dentition.

Annual review of selected scientific literature: A report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry

The Scientific Investigation Committee of the American Academy of Restorative Dentistry offers this review of the 2020 professional literature in restorative dentistry to inform busy dentists regarding noteworthy scientific and clinical progress over the past year. Each member of the committee brings discipline-specific expertise to this work to cover this broad topic. Specific subject areas addressed include prosthodontics; periodontics, alveolar bone, and peri-implant tissues; implant dentistry; dental materials and therapeutics; occlusion and temporomandibular disorders (TMDs); sleep-related breathing disorders; oral medicine and oral and maxillofacial surgery; and dental caries and cariology. The authors focused their efforts on reporting information likely to influence day-to-day dental treatment decisions with a keen eye on future trends in the profession. With the tremendous volume of dentistry and related literature being published today, this review cannot possibly be comprehensive. The purpose is to update interested readers and provide important resource material for those interested in pursuing greater detail. It remains our intent to assist colleagues in navigating the extensive volume of important information being published annually. It is our hope that readers find this work useful in successfully managing the dental patients they encounter.

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

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