Amino Sugars Reshape Interactions between Streptococcus mutans and Streptococcus gordonii

Abstract

Amino sugars, particularly glucosamine (GlcN) and N-acetylglucosamine (GlcNAc), are abundant carbon and nitrogen sources supplied in host secretions and in the diet to the biofilms colonizing the human oral cavity. Evidence is emerging that these amino sugars provide ecological advantages to beneficial commensals over oral pathogens and pathobionts. Here, we performed transcriptome analysis on Streptococcus mutans and Streptococcus gordonii growing in single-species or dual-species cultures with glucose, GlcN or GlcNAc as the primary carbohydrate source. Compared to glucose, GlcN caused drastic transcriptomic shifts in each bacterium when they were cultured alone. Likewise, co-cultivation in the presence of GlcN yielded transcriptomic profiles that were dramatically different than the single-species results from GlcN-grown cells. In contrast, GlcNAc elicited only minor changes in the transcriptome of either organism in single- and dual-species cultures. Interestingly, genes involved in pyruvate metabolism were among the most significantly affected by GlcN in both species, and these changes were consistent with measurements of pyruvate in culture supernates. Differing from a previous report, growth of S. mutans alone with GlcN inhibited expression of multiple operons required for mutacin production. Co-cultivation with S. gordonii consistently increased the expression by S. mutans of two manganese transporter operons (slo and mntH) and decreased expression of mutacin genes. Conversely, S. gordonii appeared to be less affected by the presence of S. mutans, but did show increases in genes for biosynthetic processes in the co-cultures. In conclusion, amino sugars profoundly alter the interactions between a pathogenic and commensal streptococcus by reprogramming central metabolism. IMPORTANCE Carbohydrate metabolism is central to the development of dental caries. A variety of sugars available to dental microorganisms influence the development of caries by affecting the physiology, ecology, and pathogenic potential of tooth biofilms. Using two well-characterized oral bacteria, one pathogen (Streptococcus mutans) and one commensal (Streptococcus gordonii) in a RNA deep-sequencing analysis, we studied the impact of two abundant amino sugars on bacterial gene expression and interspecies interactions. The results indicated large-scale remodeling of gene expression induced by GlcN in particular, affecting bacterial energy generation, acid production, protein synthesis, and release of antimicrobial molecules. Our study provides novel insights into how amino sugars modify bacterial behavior, information that will be valuable in the design of new technologies to detect and prevent oral infectious diseases.

The Effect of Amino Sugars on the Composition and Metabolism of a Microcosm Biofilm and the Cariogenic Potential against Teeth and Dental Materials

“…Previous studies [ 9 , 10 , 13 ] showed that oral streptococci released increased amounts of H 2 O 2 and ammonia after GlcNAc metabolism under similar conditions. To evaluate the effect of these products individually, 6 samples of each group were used.…”

“…Based on the microbial composition of each biofilm and our prior research on amino sugars and individual bacterial species [ 10 , 13 ], bacterial cells from CCS biofilms formed with glucose or GlcNAc were selected for metabolomic analysis using LC-MS targeting 8 organic acids, namely lactate, pyruvate, succinate, 3-hydroxybutyrate, α-ketoglutarate, malate, citrate, and fumarate. Bacterial cell pellets were shipped to the service provider on dry ice and stored at −80 °C.…”

“…Amino sugar metabolism also promoted expression by commensals of arginine deiminase, which can act upon arginine for the generation of ATP and release of ammonia [ 12 ]. Furthermore, a recent transcriptomic study suggested the ability of amino sugars to modify bacterial central metabolism and reduce the production of lactic acid [ 13 ]. By increasing intracellular and environmental pH, the effects of amino sugars can greatly benefit the less acid-tolerant commensal species to potentially impede or even reverse the detrimental effects of aciduric pathogens at the microbiome level.…”

Diaryl Urea Derivative Molecule Inhibits Cariogenic Streptococcus mutans by Affecting Exopolysaccharide Synthesis, Stress Response, and Nitrogen Metabolism

“…By metabolizing nitrogen-containing compounds, mainly amino sugars such as glucosamine and N -acetylglucosamine, bacteria are provided with essential materials for macromolecule synthesis ( Ardin et al., 2014 ). The ability to utilize amino sugars is also closely associated with the competitiveness of bacteria to thrive in the oral cavity ( Chen et al., 2020 ). The current study reports the downregulation of genes encoding a membrane ammonium transporter ( glnB ) ( Ardin et al., 2014 ) and a glutamine synthetase regulator ( glnR ) ( Chen et al., 2010 ).…”

Glucose PTS Modulates Pyruvate Metabolism, Bacterial Fitness, and Microbial Ecology in Oral Streptococci

“…RNA deep sequencing for SK36 and the manL mutant was carried out by Microbial Genome Sequencing Center (MiGS, Pittsburgh, PA). The analysis of the RNA-Seq data was conducted on package R (94), following an established protocol detailed elsewhere (95). The compositional matrix of the expression data was normalized with the “voom” (96) function from the R package “limma” (97).…”