Ontology highlight
ABSTRACT:
PROVIDER: PRJNA1021815 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR26222553_1.fastq.gz | Fastqsanger.gz | |||
| SRR26222553_2.fastq.gz | Fastqsanger.gz | |||
| SRR26222554_1.fastq.gz | Fastqsanger.gz | |||
| SRR26222554_2.fastq.gz | Fastqsanger.gz | |||
| SRR26222555_1.fastq.gz | Fastqsanger.gz |
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Project description:Within the mouth bacteria are starved of saccharides as their main nutrient source between meals and it is unclear what drives their metabolism. Previously oral in vitro biofilms grown in saliva have shown proteolytic degradation of salivary proteins and increased extracellular proline. Although arginine and glucose have been shown before to have an effect on oral biofilm growth and activity, there is limited evidence for proline. Nuclear magnetic resonance (NMR) spectroscopy was used to identify extracellular metabolites produced by bacteria in oral biofilms grown on hydroxyapatite discs. Biofilms were inoculated with whole mouth saliva and then grown for 7 days using sterilised whole mouth saliva supplemented with proline, arginine and glucose as a growth-medium. Overall proline had a beneficial effect on biofilm growth – with significantly fewer dead bacteria present by biomass and surface area of the biofilms (p <0.05). Where arginine and glucose significantly increased and decreased pH, respectively, the pH of proline supplemented biofilms remained neutral at pH 7.3-7.5. SDS-polyacrylamide gel electrophoresis of the spent saliva from proline and arginine supplemented biofilms showed inhibition of salivary protein degradation of immature biofilms. NMR analysis of the spent saliva revealed that proline supplemented biofilms were metabolically similar to unsupplemented biofilms, but these biofilms actively metabolised proline to 5-aminopentanoate, butyrate and propionate, and actively utilised glycine. This study shows that in a nutrient limited environment, proline has a beneficial effect on in vitro oral biofilms grown from a saliva inoculum.
2020-07-23 | ST001433 | MetabolomicsWorkbench
Project description:Recent studies have shown phenotypic and metabolic heterogeneity in related species including Streptococcus oralis, a typical oral commensal bacterium, Streptococcus mutans, a cariogenic bacterium, and Streptococcus gordonii, which functions as an accessory pathogen in periodontopathic biofilm. In this study, metabolites characteristically contained in the saliva of individuals with good oral hygiene were determined, after which the effects of an identified prebiotic candidate, D-tagatose, on phenotype, gene expression, and metabolic profiles of those three key bacterial species were investigated. Examinations of the saliva metabolome of 18 systemically healthy volunteers identified salivary D-tagatose as associated with lower dental biofilm abundance in the oral cavity (Spearman’s correlation coefficient; r = -0.603, p = 0.008), then the effects of D-tagatose on oral streptococci were analyzed in vitro. In chemically defined medium (CDM) containing D-tagatose as the sole carbohydrate source, S. mutans and S. gordonii each showed negligible biofilm formation, whereas significant biofilms were formed in cultures of S. oralis. Furthermore, even in the presence of glucose, S. mutans and S. gordonii showed growth suppression and decreases in the final viable cell count in a D-tagatose concentration-dependent manner. In contrast, no inhibitory effects of D-tagatose on the growth of S. oralis were observed. To investigate species-specific inhibition by D-tagatose, the metabolomic profiles of D-tagatose-treated S. mutans, S. gordonii, and S. oralis cells were examined. The intracellular amounts of pyruvate-derived amino acids in S. mutans and S. gordonii, but not in S. oralis, such as branched-chain amino acids and alanine, tended to decrease in the presence of D-tagatose. This phenomenon indicates that D-tagatose inhibits growth of those bacteria by affecting glycolysis and its downstream metabolism. In conclusion, the present study provides evidence that D-tagatose is abundant in saliva of individuals with good oral health. Additionally, experimental results demonstrated that D-tagatose selectively inhibits growth of the oral pathogens S. mutans and S. gordonii. In contrast, the oral commensal S. oralis seemed to be negligibly affected, thus highlighting the potential of administration of D-tagatose as an oral prebiotic for its ability to manipulate the metabolism of those targeted oral streptococci.
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Project description:Human saliva modifies growth, biofilm architecture and competitive behaviors of oral streptococci
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Project description:Enterococcus faecalis is a commensal bacterium in the gastrointestinal tract (GIT) of humans and other organisms. Outside of the GIT, E. faecalis can cause infections in root canals, wounds, surgical sites, the urinary tract, and on heart valves. Many of these infections can be polymicrobial, and a variety of toxins and nutritional signals influence interactions between E. faecalis and other microbes. Like other bacteria, E. faecalis metabolizes arginine through the arginine deiminase (ADI) pathway, which converts arginine to ornithine and releases ATP, ammonia, and CO2. E. faecalis arginine metabolism also affects virulence of other pathogens, such as Clostridioides difficile and Escherichia coli, during co-culture. E. faecalis may encounter elevated levels of arginine in the GIT or the oral cavity, where arginine is used as an additive in dental therapeutics to disrupt plaque formation and biofilm growth by oral streptococci. However, little is known about how E. faecalis responds to growth in arginine. To address this gap, we used RNAseq and additional in vitro assays to measure changes in growth, gene expression, and biofilm formation in arginine relative to control conditions. Here, we demonstrate that arginine decreases E. faecalis biofilm production and causes widespread differential expression of genes related to metabolism, nutrient transport, quorum sensing, and polysaccharide synthesis. Growth in arginine also increases aggregation of E. faecalis cultures and promotes decreased susceptibility to the antibiotics ampicillin and ceftriaxone. Together, this shows that E. faecalis undergoes global transcriptional changes during growth in arginine and provides a platform for better understanding of how the presence of arginine in the niches colonized by E. faecalis affects the physiology of this organism in addition to the virulence of surrounding microbes.
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Project description:Asymptomatic colonization of the upper respiratory tract is a common trait of the two exclusive human pathogens, Neisseria gonorrhoeae and Neisseria meningitidis. In vivo models of pathogenic neisserial infections are heterologous systems that permit short-term persistence but do not fully recapitulate infections in humans. Studying Neisseria musculi (Nmus), an oral commensal, in laboratory mice allows investigation of Neisseria-host interactions that avoids host restriction barriers. Nmus produces smooth and rough morphotypes on solid media. We compared the in vitro phenotypes, biofilm transcriptomes, and in vivo colonization patterns and burdens of the Nmus morphotypes. We observed that the two morphotypes differ in biofilm formation, aggregation, pilin production, and transformation frequency in vitro. These phenotypes strongly correlated with differential expression of a set of genes in the Nmus biofilms including those that encoded factors for bacterial attachment. In vivo, the smooth morphotype stably colonized the oral cavities of all inoculated A/J and C57BL/6J mice at higher burdens compared to the rough. Following nasal inoculations, we detected transient Nmus nasal colonization. The smooth morphotype was able to reach higher burdens more quickly in the nasal cavity and on oral swabs following dissemination to the oral cavity. Gut colonization burdens fluctuated over time. Interestingly, both morphotypes colonized the oral cavities of A/Js at higher magnitudes than in C57BL/6Js. Collectively, our results demonstrate that colonization by Nmus can be affected by various factors including Nmus morphotypes, inoculation routes, anatomical niches, and host backgrounds. The Nmus-mouse model can use variable morphotype-host combinations to study the dynamics of neisserial asymptomatic colonization and persistence in multiple extragenital niches.
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