Project description:RNA-Seq was used to compare the transcriptome of Streptococcus mutans UA159 during growth alone in monoculture, in coculture with Streptococcus gordonii DL1, Streptococcus sanguinis SK36 or Streptococcus oralis 34, and in a quadculture containing all four species. Individual cultures of commensal species Streptococcus gordonii DL1, Streptococcus sanguinis SK36 and Streptococcus oralis 34 were sequenced as well. This revealed a common transcriptome pattern in S. mutans when grown in mixed-species culture, indepenedent of the species identity that S. mutans was cultured with. Additionally, transcriptome changes in the commensal species could also be determined when undergoing competition from S. mutans. RNA-Seq was used to compare the transcriptome of Streptococcus mutans UA159 during growth alone in monoculture or in coculture with Streptococcus sobrinus NIDR 6715, Lactobacillus casei ATCC 4646 or Corynebacterium matruchotii ATCC 14266. These data were compared to previous coculture and quadculture RNA-Seq data with commensal streptococci (GSE209925). These data confirmed a common transcriptome pattern in S. mutans when grown in mixed-species culture with commensal streptococci that is not present with non-commensal streptococci, indepenedent of the species identity that S. mutans was cultured with.
Project description:Streptococcus sanguinis is a major component of the oral flora and an important cause of infective endocarditis. The genome sequence of S. sanguinis strain SK36 was recently determined. A number of foreign genes acquired by natural transformation were detected, as well as orthologs of competence genes previously identified in other species. However, significant differences in the S. sanguinis competence system relative to that of other streptococci were noted. We sought to examine S. sanguinis genetic competence, to characterize the global transcriptional response to competence induction, and to compare our results with those obtained from previous analyses of other streptococci. A mutant possessing an in-frame deletion in the comC gene encoding the competence-stimulating peptide was created and confirmed to have the expected phenotype. Studies indicated that competence could be induced in this strain by addition of competence-stimulating peptide, and determined the optimal conditions to employ for this purpose. Expression was monitored by microarray analysis at multiple time points from 2.5 to 30 min after induction. Over 200 genes were identified whose expression was altered at least two-fold in at least one time point, with the majority upregulated. The “late” response was typical of that seen in previous studies. However, comparison of the “early” response in S. sanguinis with that of other streptococci revealed unexpected heterogeneity with regard to the number of genes induced, the nature of these genes, and their putative upstream regulatory sequences. S. sanguinis possesses a comparatively limited early response, which may define a minimal competence regulatory circuit.
Project description:Oral commensal streptococci play a large role in mediating microbial homeostasis. Our published findings have demonstrated that hydrogen peroxide (H2O2) produced by oral commensal streptococci can react with salivary nitrite (NO2) and generate peroxynitrite (ONOO-), a potent antimicrobial. We have shown that the combinatorial antimicrobial effects of NO2 and H2O2 produced from the commensal Streptococcus parasanguinis, inhibit the colonization and pathogenesis of oral pathogens to promote homeostasis. Remarkably, S. parasanguinis is highly resistant to the NO2 and ONOO-. However, it remains unclear how S. parasanguinis copes in the presence of nitrosative stress. The goal of this study was to identify mechanisms used by S. parasanguinis to resist NO2-mediated nitrosative stress using a transcriptomics approach. Transcriptomic analysis showed that the competence response regulator, comE, is upregulated in the presence of NO2. Loss of comE resulted in a decrease in biofilm development, H2O2 production, increased acid tolerance and sensitivity to ONOO- compared to wild-type S. parasanguinis. Our data show that ComE is critical for key aspects of S. parasanguinis physiology and potentially impacts this commensal's ability to colonize and modulate homeostasis in the oral cavity.
Project description:Small distortions in transcriptional networks might lead to drastic phenotypical changes, especially in cellular developmental programs such as competence for natural transformation. Here, we report a pervasive circuitry rewiring for competence and predation interplay in commensal streptococci. Canonically, in model species of streptococci such as Streptococcus pneumoniae and Streptococcus mutans, the pheromone-based two-component system BlpRH is a central node that orchestrates the production of antimicrobial compounds (bacteriocins) and incorporates signal from the competence activation cascade. However, the human commensal Streptococcus salivarius does not contain a functional BlpRH pair and in this species, the competence signaling system ComRS directly couples bacteriocin production and competence commitment. This network shortcut might account for an optimal reaction against microbial competitors and could explain the high prevalence of S. salivarius in the human digestive tract. Moreover, the broad spectrum of bacteriocin activity against pathogenic bacteria showcases the commensal and genetically tractable S. salivarius species as a user-friendly model for natural transformation and bacterial predation.
Project description:Our group recently transcriptomically characterized coculture growth between Streptococcus mutans and several species of commensal streptococci (Rose et al, 2023; Choi et al 2024). One interaction that stood out was with Streptococcus mitis ATCC 49456, which completely inhibited the growth of S. mutans during biofilm formation. This is due to abudant hydrogen peroxide production by S. mitis ATCC 49456, 3-5x higher than other oral commensal streptococci we have worked with. To understand how the transcriptome of S. mutans is modified in coculture with a high hydrogen peroxide producer, we evaluated the transcriptome during monoculture or coculture growth between the two strains. Our results show differential gene expression (DEGs) in S. mutans that follows other trends we have documented previously with other commensal Streptococcus species, as well as DEGs specific to the interaction with S. mitis.
Project description:Streptococcus sanguinis is a major component of the oral flora and an important cause of infective endocarditis. The genome sequence of S. sanguinis strain SK36 was recently determined. A number of foreign genes acquired by natural transformation were detected, as well as orthologs of competence genes previously identified in other species. However, significant differences in the S. sanguinis competence system relative to that of other streptococci were noted. We sought to examine S. sanguinis genetic competence, to characterize the global transcriptional response to competence induction, and to compare our results with those obtained from previous analyses of other streptococci. A mutant possessing an in-frame deletion in the comC gene encoding the competence-stimulating peptide was created and confirmed to have the expected phenotype. Studies indicated that competence could be induced in this strain by addition of competence-stimulating peptide, and determined the optimal conditions to employ for this purpose. Expression was monitored by microarray analysis at multiple time points from 2.5 to 30 min after induction. Over 200 genes were identified whose expression was altered at least two-fold in at least one time point, with the majority upregulated. The M-bM-^@M-^\lateM-bM-^@M-^] response was typical of that seen in previous studies. However, comparison of the M-bM-^@M-^\earlyM-bM-^@M-^] response in S. sanguinis with that of other streptococci revealed unexpected heterogeneity with regard to the number of genes induced, the nature of these genes, and their putative upstream regulatory sequences. S. sanguinis possesses a comparatively limited early response, which may define a minimal competence regulatory circuit. Transcriptional analysis of S. sanguinis strain JFP41 cells 0 to 30 min after treatment with CSP. Biological replicates: 3 replicates each independently grown and harvested. 4 technical replicates per array