Project description:Our group recently transcriptomically characterized coculture growth between Streptococcus mutans and several species of commensal streptococci (Rose et al, 2023). However, these experiments were carried out in our lab-based experimental medium, tryptone and yeast extract (TY-). To understand whether culturing these species within a medium that more closely mimics their natural environment alters the interaction, we evaluated both monoculture and coculture growth between the dental caries pathogen Streptococcus mutans and oral commensal species Streptococcus oralis in a half TY- / half human saliva mix that was optimally chosen based on our initial characterization of oral streptococci behaviors in medium mixes containing saliva. Our results surprising show that inclusion of saliva enhances the competition of Streptococcus mutans against commensal streptococci through upregulation of carbohydrate uptake and glycolytic pathways.
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.
Project description:<p>Bacterial metabolism in oral biofilms is comprised of complex networks of nutritional chains and biochemical regulations. These processes involve both intraspecies and interspecies networks as well as interactions with components from host saliva, gingival crevicular fluid, and dietary intake. In a previous paper, a large salivary glycoprotein, mucin MUC5B, was suggested to promote a dental health-related phenotype in the oral type strain of <em>Streptococcus gordonii</em> DL1, by regulating bacterial adhesion and protein expression. In this study, nuclear magnetic resonance-based metabolomics was used to examine the effects on the metabolic output of monospecies compared to dual species early biofilms of two clinical strains of oral commensal bacteria, <em>S. gordonii</em> and <em>Actinomyces naeslundii</em>, in the presence of MUC5B. The presence of <em>S. gordonii</em> increased colonization of <em>A. naeslundii</em> on salivary MUC5B, and both commensals were able to utilize MUC5B as a sole nutrient source during early biofilm formation. The metabolomes suggested that the bacteria were able to release mucin carbohydrates from oligosaccharide side chains as well as amino acids from the protein core. Synergistic effects were also seen in the dual species biofilm metabolome compared to the monospecies, indicating that <em>A. naeslundii</em> and <em>S. gordonii</em> cooperated in the degradation of salivary MUC5B. A better understanding of bacterial interactions and salivary-mediated regulation of early dental biofilm activity is meaningful for understanding oral biofilm physiology and may contribute to the development of future prevention strategies for biofilm-induced oral disease.</p>
Project description:Protease activity has been associated with pathological processes that can lead to cancer development and progression. However, understanding the pathological unbalance in proteolysis is challenging since changes can occur simultaneously at protease, their inhibitor and substrate levels. In this work we combined peptidomics, proteomics and peptidase predictions for studying proteolytic events in saliva associated with oral squamous cell carcinoma (OSCC) prognosis. Our results suggest that cleavage products differentially abundant in the saliva of patients with (N+) or without (N0) nodal metastasis exhibit potential of prognostic value in oral cancer and were are able to discriminate N+ and N0 patients whereas reduced protein levels of peptidase inhibitors might disturb the proteolytic balance in saliva of OSCC patients with poor prognosis
Project description:Investigation of whole genome gene expression levels of P. gingivalis W83, F. nucleatum DSMZ 25586, S. sanguinis SK36, A. actinomycetemcomitans HK1651, S. mutans UA159 in an 24 h old culture. Additionally, whole genome gene expression level changes of S. mutans UA159 biofilm cells after co-cultivation with S. mitis ATCC 11843 were compared to its single species biofilm growth after 24 h. Aim: Demonstration of the usefulness of a five-species gene expression array. Multiple probes per gene enabled identification of single inter-species cross-hybridizing probes. The deletion of such probes lead almost not to the deletion of the whole gene. This was investigated and confirmed by a two-species biofilm expression analysis: The here described array was used for the identification of genes of S. mutans influenced by the presence of S. mitis. Materials and Methods: P. gingivalis W83, F. nucleatum DSMZ 25586, S. sanguinis SK36, A. actinomycetemcomitans HK1651,and S. mutans UA159 were grown in CDM/succrose or artificial saliva/galactose in a single-species culture for 24 h anaerobically resulting in biofilm structures or monolayers. Total RNA was isolated and used for microarray analysis. Probes were analysed for the presence of biological false positive signals caused by cross-hybridizing probes of one of the other species presented on the chip. Further, a simple procedure was developed for automatical identification and deletion of false positive signals caused by washing artefacts, resulting in a more reliable outcome. In the case of the S. mutans/S. mitis mixed-species biofilm, both species were cultured together for 24 h like previously described. The found gene regulations were verified by RT-PCR. Results: Experiments with cDNA from 24 h old single-species cultures allowed the identification of cross-species hybridizing probes on the array, which can be eliminated in mixed-species experimental settings without the need to exclude the whole genes from the analysis. Between 69 % and almost 100 % represented genomes on this array were found actively transcribed under the mono-species monolayer and biofilm conditions used here. S. mutans / S. mitis co-culture: Physiological investigations revealed an increase in S. mutans biofilm mass with a decrease in pH-value under the influence of S. mitis, thereby confirming previously published data. A stringent fold change cut-off of 2 (p<0.05) identified 19 S. mutans transcripts with increased abundance, and 11 with decreased abundance compared to a S. mutans mono-species biofilm. Many of the genes have previously been found differentially regulated under general and acid stress, thereby confirming the value of this array. Conclusions: Taken together, this new array allows transcriptome studies on multi-species oral biofilm interactions and could become an important asset in future oral biofilm and inhibitor/therapy studies.
Project description:Investigation of whole genome gene expression levels of P. gingivalis W83, F. nucleatum DSMZ 25586, S. sanguinis SK36, A. actinomycetemcomitans HK1651, S. mutans UA159 in an 24 h old culture. Additionally, whole genome gene expression level changes of S. mutans UA159 biofilm cells after co-cultivation with S. mitis ATCC 11843 were compared to its single species biofilm growth after 24 h. Aim: Demonstration of the usefulness of a five-species gene expression array. Multiple probes per gene enabled identification of single inter-species cross-hybridizing probes. The deletion of such probes lead almost not to the deletion of the whole gene. This was investigated and confirmed by a two-species biofilm expression analysis: The here described array was used for the identification of genes of S. mutans influenced by the presence of S. mitis. Materials and Methods: P. gingivalis W83, F. nucleatum DSMZ 25586, S. sanguinis SK36, A. actinomycetemcomitans HK1651,and S. mutans UA159 were grown in CDM/succrose or artificial saliva/galactose in a single-species culture for 24 h anaerobically resulting in biofilm structures or monolayers. Total RNA was isolated and used for microarray analysis. Probes were analysed for the presence of biological false positive signals caused by cross-hybridizing probes of one of the other species presented on the chip. Further, a simple procedure was developed for automatical identification and deletion of false positive signals caused by washing artefacts, resulting in a more reliable outcome. In the case of the S. mutans/S. mitis mixed-species biofilm, both species were cultured together for 24 h like previously described. The found gene regulations were verified by RT-PCR. Results: Experiments with cDNA from 24 h old single-species cultures allowed the identification of cross-species hybridizing probes on the array, which can be eliminated in mixed-species experimental settings without the need to exclude the whole genes from the analysis. Between 69 % and almost 100 % represented genomes on this array were found actively transcribed under the mono-species monolayer and biofilm conditions used here. S. mutans / S. mitis co-culture: Physiological investigations revealed an increase in S. mutans biofilm mass with a decrease in pH-value under the influence of S. mitis, thereby confirming previously published data. A stringent fold change cut-off of 2 (p<0.05) identified 19 S. mutans transcripts with increased abundance, and 11 with decreased abundance compared to a S. mutans mono-species biofilm. Many of the genes have previously been found differentially regulated under general and acid stress, thereby confirming the value of this array. Conclusions: Taken together, this new array allows transcriptome studies on multi-species oral biofilm interactions and could become an important asset in future oral biofilm and inhibitor/therapy studies. The chip study used pooled total RNA recovered from three biologically independent mono-species biofilms or adherent cells/monolayers of P. gingivalis W83, F. nucleatum DSMZ 25586, S. sanguinis SK36, A. actinomycetemcomitans HK1651, and S. mutans UA159. In the case of gene expression analysis of S. mutans/S.mitis biofilm structures compared to the single species biofilm of S. mutans three separate single and three separate two-species biofilm cultures were analysed. Each chip measured the expression level of all together 10186 genes (1883 genes of P. gingivalis W83, 1964 genes of F. nucleatum DSMZ 25586, 2244 genes of S. sanguinis SK36, 2168 genes of A. actinomycetemcomitans HK1651, 1927 genes of S. mutans UA159) with up to thirteen 60-mer probes per gene and with a three-fold technical redundancy.